mongo

package
v1.4.2 Latest Latest
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 Go to latest Published: Oct 7, 2020 License: Apache-2.0 Imports: 35 Imported by: 25,709

Documentation

Overview

Package mongo provides a MongoDB Driver API for Go.

Basic usage of the driver starts with creating a Client from a connection string. To do so, call the NewClient and Connect functions: 

client, err := NewClient(options.Client().ApplyURI("mongodb://foo:bar@localhost:27017"))
if err != nil { return err }
ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
defer cancel()
err = client.Connect(ctx)
if err != nil { return err }

This will create a new client and start monitoring the MongoDB server on localhost. The Database and Collection types can be used to access the database: 

collection := client.Database("baz").Collection("qux")

A Collection can be used to query the database or insert documents: 

res, err := collection.InsertOne(context.Background(), bson.M{"hello": "world"})
if err != nil { return err }
id := res.InsertedID

Several methods return a cursor, which can be used like this: 

cur, err := collection.Find(context.Background(), bson.D{})
if err != nil { log.Fatal(err) }
defer cur.Close(context.Background())
for cur.Next(context.Background()) {
  // To decode into a struct, use cursor.Decode()
  result := struct{
    Foo string
    Bar int32
  }{}
  err := cur.Decode(&result)
  if err != nil { log.Fatal(err) }
  // do something with result...

  // To get the raw bson bytes use cursor.Current
  raw := cur.Current
  // do something with raw...
}
if err := cur.Err(); err != nil {
  return err
}

Methods that only return a single document will return a *SingleResult, which works like a *sql.Row: 

result := struct{
  Foo string
  Bar int32
}{}
filter := bson.D{{"hello", "world"}}
err := collection.FindOne(context.Background(), filter).Decode(&result)
if err != nil { return err }
// do something with result...

All Client, Collection, and Database methods that take parameters of type interface{} will return ErrNilDocument if nil is passed in for an interface{}.

Additional examples can be found under the examples directory in the driver's repository and on the MongoDB website.

Potential DNS Issues

Building with Go 1.11+ and using connection strings with the "mongodb+srv"[1] scheme is incompatible with some DNS servers in the wild due to the change introduced in https://github.com/golang/go/issues/10622. If you receive an error with the message "cannot unmarshal DNS message" while running an operation, we suggest you use a different DNS server.

Client Side Encryption

Client-side encryption is a new feature in MongoDB 4.2 that allows specific data fields to be encrypted. Using this feature requires specifying the "cse" build tag during compilation.

Note: Auto encryption is an enterprise-only feature.

The libmongocrypt C library is required when using client-side encryption. To install libmongocrypt, follow the instructions for your operating system:

1. Linux: follow the instructions listed at https://github.com/mongodb/libmongocrypt#installing-libmongocrypt-from-distribution-packages to install the correct deb/rpm package.

2. Mac: Follow the instructions listed at https://github.com/mongodb/libmongocrypt#installing-libmongocrypt-on-macos to install packages via brew and compile the libmongocrypt source code.

  1. Windows: mkdir -p c:/libmongocrypt/bin mkdir -p c:/libmongocrypt/include

    // Run the curl command in an empty directory as it will create new directories when unpacked. curl https://s3.amazonaws.com/mciuploads/libmongocrypt/windows/latest_release/libmongocrypt.tar.gz --output libmongocrypt.tar.gz tar -xvzf libmongocrypt.tar.gz

    cp ./bin/mongocrypt.dll c:/libmongocrypt/bin cp ./include/mongocrypt/*.h c:/libmongocrypt/include export PATH=$PATH:/cygdrive/c/libmongocrypt/bin

libmongocrypt communicates with the mongocryptd process for automatic encryption. This process can be started manually or auto-spawned by the driver itself. To enable auto-spawning, ensure the process binary is on the PATH. To start it manually, use AutoEncryptionOptions: 

aeo := options.AutoEncryption()
mongocryptdOpts := map[string]interface{}{
    "mongocryptdBypassSpawn": true,
}
aeo.SetExtraOptions(mongocryptdOpts)

To specify a process URI for mongocryptd, the "mongocryptdURI" option can be passed in the ExtraOptions map as well. See the ClientSideEncryption and ClientSideEncryptionCreateKey examples below for code samples about using this feature.

[1] See https://docs.mongodb.com/manual/reference/connection-string/#dns-seedlist-connection-format

Example (ClientSideEncryption) 
// This would have to be the same master key that was used to create the encryption key
localKey := make([]byte, 96)
if _, err := rand.Read(localKey); err != nil {
	log.Fatal(err)
}
kmsProviders := map[string]map[string]interface{}{
	"local": {
		"key": localKey,
	},
}
keyVaultNamespace := "admin.datakeys"

uri := "mongodb://localhost:27017"
autoEncryptionOpts := options.AutoEncryption().
	SetKeyVaultNamespace(keyVaultNamespace).
	SetKmsProviders(kmsProviders)
clientOpts := options.Client().ApplyURI(uri).SetAutoEncryptionOptions(autoEncryptionOpts)
client, err := Connect(context.TODO(), clientOpts)
if err != nil {
	log.Fatalf("Connect error: %v", err)
}
defer func() {
	if err = client.Disconnect(context.TODO()); err != nil {
		log.Fatalf("Disconnect error: %v", err)
	}
}()

collection := client.Database("test").Collection("coll")
if err := collection.Drop(context.TODO()); err != nil {
	log.Fatalf("Collection.Drop error: %v", err)
}

if _, err = collection.InsertOne(context.TODO(), bson.D{{"encryptedField", "123456789"}}); err != nil {
	log.Fatalf("InsertOne error: %v", err)
}
res, err := collection.FindOne(context.TODO(), bson.D{}).DecodeBytes()
if err != nil {
	log.Fatalf("FindOne error: %v", err)
}
fmt.Println(res)

Output:
Example (ClientSideEncryptionCreateKey) 
keyVaultNamespace := "admin.datakeys"
uri := "mongodb://localhost:27017"
// kmsProviders would have to be populated with the correct KMS provider information before it's used
var kmsProviders map[string]map[string]interface{}

// Create Client and ClientEncryption
clientEncryptionOpts := options.ClientEncryption().
	SetKeyVaultNamespace(keyVaultNamespace).
	SetKmsProviders(kmsProviders)
keyVaultClient, err := Connect(context.TODO(), options.Client().ApplyURI(uri))
if err != nil {
	log.Fatalf("Connect error for keyVaultClient: %v", err)
}
clientEnc, err := NewClientEncryption(keyVaultClient, clientEncryptionOpts)
if err != nil {
	log.Fatalf("NewClientEncryption error: %v", err)
}
defer func() {
	// this will disconnect the keyVaultClient as well
	if err = clientEnc.Close(context.TODO()); err != nil {
		log.Fatalf("Close error: %v", err)
	}
}()

// Create a new data key and encode it as base64
dataKeyID, err := clientEnc.CreateDataKey(context.TODO(), "local")
if err != nil {
	log.Fatalf("CreateDataKey error: %v", err)
}
dataKeyBase64 := base64.StdEncoding.EncodeToString(dataKeyID.Data)

// Create a JSON schema using the new data key. This schema could also be written in a separate file and read in
// using I/O functions.
schema := `{
		"properties": {
			"encryptedField": {
				"encrypt": {
					"keyId": [{
						"$binary": {
							"base64": "%s",
							"subType": "04"
						}
					}],
					"bsonType": "string",
					"algorithm": "AEAD_AES_256_CBC_HMAC_SHA_512-Deterministic"
				}
			}
		},
		"bsonType": "object"
	}`
schema = fmt.Sprintf(schema, dataKeyBase64)
var schemaDoc bson.Raw
if err = bson.UnmarshalExtJSON([]byte(schema), true, &schemaDoc); err != nil {
	log.Fatalf("UnmarshalExtJSON error: %v", err)
}

// Configure a Client with auto encryption using the new schema
dbName := "test"
collName := "coll"
schemaMap := map[string]interface{}{
	dbName + "." + collName: schemaDoc,
}
autoEncryptionOpts := options.AutoEncryption().
	SetKmsProviders(kmsProviders).
	SetKeyVaultNamespace(keyVaultNamespace).
	SetSchemaMap(schemaMap)
client, err := Connect(context.TODO(), options.Client().ApplyURI(uri).SetAutoEncryptionOptions(autoEncryptionOpts))
if err != nil {
	log.Fatalf("Connect error for encrypted client: %v", err)
}
defer func() {
	_ = client.Disconnect(context.TODO())
}()

// Use client for operations.

Output:
Example (ExplictEncryption) 
var localMasterKey []byte // This must be the same master key that was used to create the encryption key.
kmsProviders := map[string]map[string]interface{}{
	"local": {
		"key": localMasterKey,
	},
}

// The MongoDB namespace (db.collection) used to store the encryption data keys.
keyVaultDBName, keyVaultCollName := "encryption", "testKeyVault"
keyVaultNamespace := keyVaultDBName + "." + keyVaultCollName

// The Client used to read/write application data.
client, err := Connect(context.TODO(), options.Client().ApplyURI("mongodb://localhost:27017"))
if err != nil {
	panic(err)
}
defer func() { _ = client.Disconnect(context.TODO()) }()

// Get a handle to the application collection and clear existing data.
coll := client.Database("test").Collection("coll")
_ = coll.Drop(context.TODO())

// Set up the key vault for this example.
keyVaultColl := client.Database(keyVaultDBName).Collection(keyVaultCollName)
_ = keyVaultColl.Drop(context.TODO())
// Ensure that two data keys cannot share the same keyAltName.
keyVaultIndex := IndexModel{
	Keys: bson.D{{"keyAltNames", 1}},
	Options: options.Index().
		SetUnique(true).
		SetPartialFilterExpression(bson.D{
			{"keyAltNames", bson.D{
				{"$exists", true},
			}},
		}),
}
if _, err = keyVaultColl.Indexes().CreateOne(context.TODO(), keyVaultIndex); err != nil {
	panic(err)
}

// Create the ClientEncryption object to use for explicit encryption/decryption. The Client passed to
// NewClientEncryption is used to read/write to the key vault. This can be the same Client used by the main
// application.
clientEncryptionOpts := options.ClientEncryption().
	SetKmsProviders(kmsProviders).
	SetKeyVaultNamespace(keyVaultNamespace)
clientEncryption, err := NewClientEncryption(client, clientEncryptionOpts)
if err != nil {
	panic(err)
}
defer func() { _ = clientEncryption.Close(context.TODO()) }()

// Create a new data key for the encrypted field.
dataKeyOpts := options.DataKey().SetKeyAltNames([]string{"go_encryption_example"})
dataKeyID, err := clientEncryption.CreateDataKey(context.TODO(), "local", dataKeyOpts)
if err != nil {
	panic(err)
}

// Create a bson.RawValue to encrypt and encrypt it using the key that was just created.
rawValueType, rawValueData, err := bson.MarshalValue("123456789")
if err != nil {
	panic(err)
}
rawValue := bson.RawValue{Type: rawValueType, Value: rawValueData}
encryptionOpts := options.Encrypt().
	SetAlgorithm("AEAD_AES_256_CBC_HMAC_SHA_512-Deterministic").
	SetKeyID(dataKeyID)
encryptedField, err := clientEncryption.Encrypt(context.TODO(), rawValue, encryptionOpts)
if err != nil {
	panic(err)
}

// Insert a document with the encrypted field and then find it.
if _, err = coll.InsertOne(context.TODO(), bson.D{{"encryptedField", encryptedField}}); err != nil {
	panic(err)
}
var foundDoc bson.M
if err = coll.FindOne(context.TODO(), bson.D{}).Decode(&foundDoc); err != nil {
	panic(err)
}

// Decrypt the encrypted field in the found document.
decrypted, err := clientEncryption.Decrypt(context.TODO(), foundDoc["encryptedField"].(primitive.Binary))
if err != nil {
	panic(err)
}
fmt.Printf("Decrypted value: %s\n", decrypted)

Output:
Example (ExplictEncryptionWithAutomaticDecryption) 
// Automatic encryption requires MongoDB 4.2 enterprise, but automatic decryption is supported for all users.

var localMasterKey []byte // This must be the same master key that was used to create the encryption key.
kmsProviders := map[string]map[string]interface{}{
	"local": {
		"key": localMasterKey,
	},
}

// The MongoDB namespace (db.collection) used to store the encryption data keys.
keyVaultDBName, keyVaultCollName := "encryption", "testKeyVault"
keyVaultNamespace := keyVaultDBName + "." + keyVaultCollName

// Create the Client for reading/writing application data. Configure it with BypassAutoEncryption=true to disable
// automatic encryption but keep automatic decryption. Setting BypassAutoEncryption will also bypass spawning
// mongocryptd in the driver.
autoEncryptionOpts := options.AutoEncryption().
	SetKmsProviders(kmsProviders).
	SetKeyVaultNamespace(keyVaultNamespace).
	SetBypassAutoEncryption(true)
clientOpts := options.Client().
	ApplyURI("mongodb://localhost:27017").
	SetAutoEncryptionOptions(autoEncryptionOpts)
client, err := Connect(context.TODO(), clientOpts)
if err != nil {
	panic(err)
}
defer func() { _ = client.Disconnect(context.TODO()) }()

// Get a handle to the application collection and clear existing data.
coll := client.Database("test").Collection("coll")
_ = coll.Drop(context.TODO())

// Set up the key vault for this example.
keyVaultColl := client.Database(keyVaultDBName).Collection(keyVaultCollName)
_ = keyVaultColl.Drop(context.TODO())
// Ensure that two data keys cannot share the same keyAltName.
keyVaultIndex := IndexModel{
	Keys: bson.D{{"keyAltNames", 1}},
	Options: options.Index().
		SetUnique(true).
		SetPartialFilterExpression(bson.D{
			{"keyAltNames", bson.D{
				{"$exists", true},
			}},
		}),
}
if _, err = keyVaultColl.Indexes().CreateOne(context.TODO(), keyVaultIndex); err != nil {
	panic(err)
}

// Create the ClientEncryption object to use for explicit encryption/decryption. The Client passed to
// NewClientEncryption is used to read/write to the key vault. This can be the same Client used by the main
// application.
clientEncryptionOpts := options.ClientEncryption().
	SetKmsProviders(kmsProviders).
	SetKeyVaultNamespace(keyVaultNamespace)
clientEncryption, err := NewClientEncryption(client, clientEncryptionOpts)
if err != nil {
	panic(err)
}
defer func() { _ = clientEncryption.Close(context.TODO()) }()

// Create a new data key for the encrypted field.
dataKeyOpts := options.DataKey().SetKeyAltNames([]string{"go_encryption_example"})
dataKeyID, err := clientEncryption.CreateDataKey(context.TODO(), "local", dataKeyOpts)
if err != nil {
	panic(err)
}

// Create a bson.RawValue to encrypt and encrypt it using the key that was just created.
rawValueType, rawValueData, err := bson.MarshalValue("123456789")
if err != nil {
	panic(err)
}
rawValue := bson.RawValue{Type: rawValueType, Value: rawValueData}
encryptionOpts := options.Encrypt().
	SetAlgorithm("AEAD_AES_256_CBC_HMAC_SHA_512-Deterministic").
	SetKeyID(dataKeyID)
encryptedField, err := clientEncryption.Encrypt(context.TODO(), rawValue, encryptionOpts)
if err != nil {
	panic(err)
}

// Insert a document with the encrypted field and then find it. The FindOne call will automatically decrypt the
// field in the document.
if _, err = coll.InsertOne(context.TODO(), bson.D{{"encryptedField", encryptedField}}); err != nil {
	panic(err)
}
var foundDoc bson.M
if err = coll.FindOne(context.TODO(), bson.D{}).Decode(&foundDoc); err != nil {
	panic(err)
}
fmt.Printf("Decrypted document: %v\n", foundDoc)

Output:

Index

Examples

Constants

This section is empty.

Variables

View Source 
var (
	// ErrMissingResumeToken indicates that a change stream notification from the server did not contain a resume token.
	ErrMissingResumeToken = errors.New("cannot provide resume functionality when the resume token is missing")
	// ErrNilCursor indicates that the underlying cursor for the change stream is nil.
	ErrNilCursor = errors.New("cursor is nil")
)
View Source 
var ErrClientDisconnected = errors.New("client is disconnected")

ErrClientDisconnected is returned when disconnected Client is used to run an operation.

View Source 
var ErrEmptySlice = errors.New("must provide at least one element in input slice")

ErrEmptySlice is returned when an empty slice is passed to a CRUD method that requires a non-empty slice.

View Source 
var ErrInvalidIndexValue = errors.New("invalid index value")

ErrInvalidIndexValue is returned if an index is created with a keys document that has a value that is not a number or string.

View Source 
var ErrMultipleIndexDrop = errors.New("multiple indexes would be dropped")

ErrMultipleIndexDrop is returned if multiple indexes would be dropped from a call to IndexView.DropOne.

View Source 
var ErrNilDocument = errors.New("document is nil")

ErrNilDocument is returned when a nil document is passed to a CRUD method.

View Source 
var ErrNilValue = errors.New("value is nil")

ErrNilValue is returned when a nil value is passed to a CRUD method.

View Source 
var ErrNoDocuments = errors.New("mongo: no documents in result")

ErrNoDocuments is returned by SingleResult methods when the operation that created the SingleResult did not return any documents.

View Source 
var ErrNonStringIndexName = errors.New("index name must be a string")

ErrNonStringIndexName is returned if an index is created with a name that is not a string.

View Source 
var ErrUnacknowledgedWrite = errors.New("unacknowledged write")

ErrUnacknowledgedWrite is returned by operations that have an unacknowledged write concern.

View Source 
var ErrWrongClient = errors.New("session was not created by this client")

ErrWrongClient is returned when a user attempts to pass in a session created by a different client than the method call is using.

Functions

func BatchCursorFromCursor deprecated added in v1.1.0 

func BatchCursorFromCursor(c *Cursor) *driver.BatchCursor

BatchCursorFromCursor returns a driver.BatchCursor for the given Cursor. If there is no underlying driver.BatchCursor, nil is returned.

Deprecated: This is an unstable function because the driver.BatchCursor type exists in the "x" package. Neither this function nor the driver.BatchCursor type should be used by applications and may be changed or removed in any release.

func WithSession added in v0.0.16 

func WithSession(ctx context.Context, sess Session, fn func(SessionContext) error) error

WithSession creates a new SessionContext from the ctx and sess parameters and uses it to call the fn callback. The SessionContext must be used as the Context parameter for any operations in the fn callback that should be executed under the session.

If the ctx parameter already contains a Session, that Session will be replaced with the one provided.

Any error returned by the fn callback will be returned without any modifications.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"go.mongodb.org/mongo-driver/mongo/readconcern"
)

func main() {
	var client *mongo.Client // assume client is configured with write concern majority and read preference primary

	// Specify the DefaultReadConcern option so any transactions started through the session will have read concern
	// majority.
	// The DefaultReadPreference and DefaultWriteConcern options aren't specified so they will be inheritied from client
	// and be set to primary and majority, respectively.
	opts := options.Session().SetDefaultReadConcern(readconcern.Majority())
	sess, err := client.StartSession(opts)
	if err != nil {
		log.Fatal(err)
	}
	defer sess.EndSession(context.TODO())

	// Call WithSession to start a transaction within the new session.
	err = mongo.WithSession(context.TODO(), sess, func(sessCtx mongo.SessionContext) error {
		// Use sessCtx as the Context parameter for InsertOne and FindOne so both operations are run under the new
		// Session.

		if err := sess.StartTransaction(); err != nil {
			return err
		}

		coll := client.Database("db").Collection("coll")
		res, err := coll.InsertOne(sessCtx, bson.D{{"x", 1}})
		if err != nil {
			// Abort the transaction after an error. Use context.Background() to ensure that the abort can complete
			// successfully even if the context passed to mongo.WithSession is changed to have a timeout.
			_ = sess.AbortTransaction(context.Background())
			return err
		}

		var result bson.M
		if err = coll.FindOne(sessCtx, bson.D{{"_id", res.InsertedID}}).Decode(result); err != nil {
			// Abort the transaction after an error. Use context.Background() to ensure that the abort can complete
			// successfully even if the context passed to mongo.WithSession is changed to have a timeout.
			_ = sess.AbortTransaction(context.Background())
			return err
		}
		fmt.Println(result)

		// Use context.Background() to ensure that the commit can complete successfully even if the context passed to
		// mongo.WithSession is changed to have a timeout.
		return sess.CommitTransaction(context.Background())
	})
}

Output:

Types

type BSONAppender added in v0.0.15 

type BSONAppender interface {
	AppendBSON([]byte, interface{}) ([]byte, error)
}

BSONAppender is an interface implemented by types that can marshal a provided type into BSON bytes and append those bytes to the provided []byte. The AppendBSON can return a non-nil error and non-nil []byte. The AppendBSON method may also write incomplete BSON to the []byte.

type BSONAppenderFunc added in v0.0.15 

type BSONAppenderFunc func([]byte, interface{}) ([]byte, error)

BSONAppenderFunc is an adapter function that allows any function that satisfies the AppendBSON method signature to be used where a BSONAppender is used.

func (BSONAppenderFunc) AppendBSON added in v0.0.15 

func (baf BSONAppenderFunc) AppendBSON(dst []byte, val interface{}) ([]byte, error)

AppendBSON implements the BSONAppender interface

type BulkWriteError added in v0.0.4 

type BulkWriteError struct {
	WriteError            // The WriteError that occurred.
	Request    WriteModel // The WriteModel that caused this error.
}

BulkWriteError is an error that occurred during execution of one operation in a BulkWrite. This error type is only returned as part of a BulkWriteException.

func (BulkWriteError) Error added in v0.0.4 

func (bwe BulkWriteError) Error() string

Error implements the error interface.

type BulkWriteException added in v0.0.16 

type BulkWriteException struct {
	// The write concern error that occurred, or nil if there was none.
	WriteConcernError *WriteConcernError

	// The write errors that occurred during operation execution.
	WriteErrors []BulkWriteError

	// The categories to which the exception belongs.
	Labels []string
}

BulkWriteException is the error type returned by BulkWrite and InsertMany operations.

func (BulkWriteException) Error added in v0.0.16 

func (bwe BulkWriteException) Error() string

Error implements the error interface.

func (BulkWriteException) HasErrorLabel added in v1.4.0 

func (bwe BulkWriteException) HasErrorLabel(label string) bool

HasErrorLabel returns true if the error contains the specified label.

type BulkWriteResult added in v0.0.16 

type BulkWriteResult struct {
	// The number of documents inserted.
	InsertedCount int64

	// The number of documents matched by filters in update and replace operations.
	MatchedCount int64

	// The number of documents modified by update and replace operations.
	ModifiedCount int64

	// The number of documents deleted.
	DeletedCount int64

	// The number of documents upserted by update and replace operations.
	UpsertedCount int64

	// A map of operation index to the _id of each upserted document.
	UpsertedIDs map[int64]interface{}
}

BulkWriteResult is the result type returned by a BulkWrite operation.

type ChangeStream added in v0.3.0 

type ChangeStream struct {
	// Current is the BSON bytes of the current event. This property is only valid until the next call to Next or
	// TryNext. If continued access is required, a copy must be made.
	Current bson.Raw
	// contains filtered or unexported fields
}

ChangeStream is used to iterate over a stream of events. Each event can be decoded into a Go type via the Decode method or accessed as raw BSON via the Current field. For more information about change streams, see https://docs.mongodb.com/manual/changeStreams/.

func (*ChangeStream) Close added in v0.3.0 

func (cs *ChangeStream) Close(ctx context.Context) error

Close closes this change stream and the underlying cursor. Next and TryNext must not be called after Close has been called. Close is idempotent. After the first call, any subsequent calls will not change the state.

func (*ChangeStream) Decode added in v0.3.0 

func (cs *ChangeStream) Decode(val interface{}) error

Decode will unmarshal the current event document into val and return any errors from the unmarshalling process without any modification. If val is nil or is a typed nil, an error will be returned.

func (*ChangeStream) Err added in v0.3.0 

func (cs *ChangeStream) Err() error

Err returns the last error seen by the change stream, or nil if no errors has occurred.

func (*ChangeStream) ID added in v0.3.0 

func (cs *ChangeStream) ID() int64

ID returns the ID for this change stream, or 0 if the cursor has been closed or exhausted.

func (*ChangeStream) Next added in v0.3.0 

func (cs *ChangeStream) Next(ctx context.Context) bool

Next gets the next event for this change stream. It returns true if there were no errors and the next event document is available.

Next blocks until an event is available, an error occurs, or ctx expires. If ctx expires, the error will be set to ctx.Err(). In an error case, Next will return false.

If Next returns false, subsequent calls will also return false.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
)

func main() {
	var stream *mongo.ChangeStream
	defer stream.Close(context.TODO())

	// Iterate the change stream and print out each event.
	// Because the Next call blocks until an event is available, another way to iterate the change stream is to call
	// Next in a goroutine and pass in a context that can be cancelled to abort the call.

	for stream.Next(context.TODO()) {
		// A new event variable should be declared for each event.
		var event bson.M
		if err := stream.Decode(&event); err != nil {
			log.Fatal(err)
		}
		fmt.Println(event)
	}
	if err := stream.Err(); err != nil {
		log.Fatal(err)
	}
}

Output:

func (*ChangeStream) ResumeToken added in v1.1.0 

func (cs *ChangeStream) ResumeToken() bson.Raw

ResumeToken returns the last cached resume token for this change stream, or nil if a resume token has not been stored.

Example 
package main

import (
	"context"
	"fmt"
	"log"
	"sync"

	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var client *mongo.Client
	var stream *mongo.ChangeStream // assume stream was created via client.Watch()

	cancelCtx, cancel := context.WithCancel(context.TODO())
	defer cancel()
	var wg sync.WaitGroup
	wg.Add(1)

	// Run a goroutine to process events.
	go func() {
		for stream.Next(cancelCtx) {
			fmt.Println(stream.Current)
		}
		wg.Done()
	}()

	// Assume client needs to be disconnected. Cancel the context being used by the goroutine to abort any
	// in-progres Next calls and wait for the goroutine to exit.
	cancel()
	wg.Wait()

	// Before disconnecting the client, store the last seen resume token for the change stream.
	resumeToken := stream.ResumeToken()
	_ = client.Disconnect(context.TODO())

	// Once a new client is created, the change stream can be re-created. Specify resumeToken as the ResumeAfter option
	// so only events that occurred after resumeToken will be returned.
	var newClient *mongo.Client
	opts := options.ChangeStream().SetResumeAfter(resumeToken)
	newStream, err := newClient.Watch(context.TODO(), mongo.Pipeline{}, opts)
	if err != nil {
		log.Fatal(err)
	}
	defer newStream.Close(context.TODO())
}

Output:

func (*ChangeStream) TryNext added in v1.2.0 

func (cs *ChangeStream) TryNext(ctx context.Context) bool

TryNext attempts to get the next event for this change stream. It returns true if there were no errors and the next event document is available.

TryNext returns false if the change stream is closed by the server, an error occurs when getting changes from the server, the next change is not yet available, or ctx expires. If ctx expires, the error will be set to ctx.Err().

If TryNext returns false and an error occurred or the change stream was closed (i.e. cs.Err() != nil || cs.ID() == 0), subsequent attempts will also return false. Otherwise, it is safe to call TryNext again until a change is available.

This method requires driver version >= 1.2.0.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
)

func main() {
	var stream *mongo.ChangeStream
	defer stream.Close(context.TODO())

	// Iterate the change stream and print out each event until the change stream is closed by the server or there is an
	// error getting the next event.
	for {
		if stream.TryNext(context.TODO()) {
			// A new event variable should be declared for each event.
			var event bson.M
			if err := stream.Decode(&event); err != nil {
				log.Fatal(err)
			}
			fmt.Println(event)
			continue
		}

		// If TryNext returns false, the next change is not yet available, the change stream was closed by the server,
		// or an error occurred. TryNext should only be called again for the empty batch case.
		if err := stream.Err(); err != nil {
			log.Fatal(err)
		}
		if stream.ID() == 0 {
			break
		}
	}
}

Output:

type Client 

type Client struct {
	// contains filtered or unexported fields
}

Client is a handle representing a pool of connections to a MongoDB deployment. It is safe for concurrent use by multiple goroutines.

The Client type opens and closes connections automatically and maintains a pool of idle connections. For connection pool configuration options, see documentation for the ClientOptions type in the mongo/options package.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	// Create a Client and execute a ListDatabases operation.

	client, err := mongo.Connect(context.TODO(), options.Client().ApplyURI("mongodb://localhost:27017"))
	if err != nil {
		log.Fatal(err)
	}
	defer func() {
		if err = client.Disconnect(context.TODO()); err != nil {
			log.Fatal(err)
		}
	}()

	collection := client.Database("db").Collection("coll")
	result, err := collection.InsertOne(context.TODO(), bson.D{{"x", 1}})
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("inserted ID: %v\n", result.InsertedID)
}

Output:

func Connect added in v0.0.3 

func Connect(ctx context.Context, opts ...*options.ClientOptions) (*Client, error)

Connect creates a new Client and then initializes it using the Connect method. This is equivalent to calling NewClient followed by Client.Connect.

When creating an options.ClientOptions, the order the methods are called matters. Later Set* methods will overwrite the values from previous Set* method invocations. This includes the ApplyURI method. This allows callers to determine the order of precedence for option application. For instance, if ApplyURI is called before SetAuth, the Credential from SetAuth will overwrite the values from the connection string. If ApplyURI is called after SetAuth, then its values will overwrite those from SetAuth.

The opts parameter is processed using options.MergeClientOptions, which will overwrite entire option fields of previous options, there is no partial overwriting. For example, if Username is set in the Auth field for the first option, and Password is set for the second but with no Username, after the merge the Username field will be empty.

The NewClient function does not do any I/O and returns an error if the given options are invalid. The Client.Connect method starts background goroutines to monitor the state of the deployment and does not do any I/O in the main goroutine to prevent the main goroutine from blocking. Therefore, it will not error if the deployment is down.

The Client.Ping method can be used to verify that the deployment is successfully connected and the Client was correctly configured.

Example (AWS) 
package main

import (
	"context"

	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	// Configure a Client with authentication using the MONGODB-AWS authentication mechanism. Credentials for this
	// mechanism can come from one of four sources:
	//
	// 1. AWS IAM credentials (an access key ID and a secret access key)
	//
	// 2. Temporary AWS IAM (https://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_temp.html) credentials
	// obtained from an AWS Security Token Service (STS) Assume Role request
	// (https://docs.aws.amazon.com/STS/latest/APIReference/API_AssumeRole.html)
	//
	// 3. AWS Lambda environment variables
	// (https://docs.aws.amazon.com/lambda/latest/dg/configuration-envvars.html#configuration-envvars-runtime)
	//
	// 4. Temporary AWS IAM credentials assigned to an EC2 instance
	// (https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_use_switch-role-ec2.html) or ECS task

	// The order in which the driver searches for credentials is:
	//
	// 1. Credentials passed through the URI
	// 2. Environment variables
	// 3. ECS endpoint if and only if AWS_CONTAINER_CREDENTIALS_RELATIVE_URI is set
	// 4. EC2 endpoint
	//
	// The following examples set the appropriate credentials via the ClientOptions.SetAuth method. All of these
	// credentials can be specified via the ClientOptions.ApplyURI method as well. If using ApplyURI, both the
	// username and password must be URL encoded (see net.URL.QueryEscape()).

	// AWS IAM Credentials

	// Applications can authenticate using AWS IAM credentials by providing a valid access key ID and secret access key
	// pair as the username and password, respectively.
	var accessKeyID, secretAccessKey string
	awsCredential := options.Credential{
		AuthMechanism: "MONGODB-AWS",
		Username:      accessKeyID,
		Password:      secretAccessKey,
	}
	awsIAMClient, err := mongo.Connect(context.TODO(), options.Client().SetAuth(awsCredential))
	if err != nil {
		panic(err)
	}
	_ = awsIAMClient

	// AssumeRole

	// Applications can authenticate using temporary credentials returned from an assume role request. These temporary
	// credentials consist of an access key ID, a secret access key, and a security token.
	var sessionToken string
	assumeRoleCredential := options.Credential{
		AuthMechanism: "MONGODB-AWS",
		Username:      accessKeyID,
		Password:      secretAccessKey,
		AuthMechanismProperties: map[string]string{
			"AWS_SESSION_TOKEN": sessionToken,
		},
	}
	assumeRoleClient, err := mongo.Connect(context.TODO(), options.Client().SetAuth(assumeRoleCredential))
	if err != nil {
		panic(err)
	}
	_ = assumeRoleClient

	// AWS Lambda (Environment Variables)

	// When the username and password are not provided and the MONGODB-AWS mechanism is set, the client will fallback to
	// using the environment variables AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, and AWS_SESSION_TOKEN for the access
	// key ID, secret access key, and session token, respectively. These environment variables must not be URL encoded.

	// $ export AWS_ACCESS_KEY_ID=<accessKeyID>
	// $ export AWS_SECRET_ACCESS_KEY=<secretAccessKey>
	// $ export AWS_SESSION_TOKEN=<sessionToken>
	envVariablesCredential := options.Credential{
		AuthMechanism: "MONGODB-AWS",
	}
	envVariablesClient, err := mongo.Connect(context.TODO(), options.Client().SetAuth(envVariablesCredential))
	if err != nil {
		panic(err)
	}
	_ = envVariablesClient

	// ECS Container or EC2 Instance

	// Applications can authenticate from an ECS container or EC2 instance via temporary credentials assigned to the
	// machine. If using an ECS container, the "AWS_CONTAINER_CREDENTIALS_RELATIVE_URI" environment variable must be
	// set to a non-empty value. The driver will query the ECS or EC2 endpoint to obtain the relevant credentials.
	ecCredential := options.Credential{
		AuthMechanism: "MONGODB-AWS",
	}
	ecClient, err := mongo.Connect(context.TODO(), options.Client().SetAuth(ecCredential))
	if err != nil {
		panic(err)
	}
	_ = ecClient
}

Output:
Example (Direct) 
package main

import (
	"context"
	"log"

	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	// Create a direct connection to a host. The driver will send all requests to that host and will not
	// automatically discover other hosts in the deployment.

	clientOpts := options.Client().ApplyURI("mongodb://localhost:27017/?connect=direct")
	client, err := mongo.Connect(context.TODO(), clientOpts)
	if err != nil {
		log.Fatal(err)
	}
	_ = client
}

Output:
Example (Kerberos) 
package main

import (
	"context"
	"log"

	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	// Configure a Client with GSSAPI/SSPI authentication (https://docs.mongodb.com/manual/core/kerberos/).
	// MongoDB Enterprise supports proxy authentication through a Kerberos service.
	// Using Kerberos authentication requires the "gssapi" build tag and cgo support during compilation.
	// The default service name for Kerberos is "mongodb". This can be configured via the AuthMechanismProperties
	// field in the options.Credential struct or the authMechanismProperties URI parameter.

	// For Linux, the libkrb5 library is required.
	// Users can authenticate in one of two ways:
	// 1. Use an explicit password. In this case, a password must be specified in the URI or the options.Credential
	// struct and no further setup is required.
	// 2. Store authentication keys in keytab files. To do this, the kinit binary should be used to initialize a
	// credential cache for authenticating the user principal. In this example, the invocation would be
	// "kinit drivers@KERBEROS.EXAMPLE.COM".

	// To configure auth via a URI instead of a Credential, use
	// "mongodb://drivers%40KERBEROS.EXAMPLE.COM@mongo-server.example.com:27017/?authMechanism=GSSAPI".
	credential := options.Credential{
		AuthMechanism: "GSSAPI",
		Username:      "drivers@KERBEROS.EXAMPLE.COM",
	}
	uri := "mongo-server.example.com:27017"
	clientOpts := options.Client().ApplyURI(uri).SetAuth(credential)

	client, err := mongo.Connect(context.TODO(), clientOpts)
	if err != nil {
		log.Fatal(err)
	}
	_ = client
}

Output:
Example (PLAIN) 
package main

import (
	"context"
	"log"

	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	// Configure a Client with LDAP authentication
	// (https://docs.mongodb.com/manual/core/authentication-mechanisms-enterprise/#security-auth-ldap).
	// MongoDB Enterprise supports proxy authentication through an LDAP service that can be used through the PLAIN
	// authentication mechanism.
	// This auth mechanism sends the password in plaintext and therefore should only be used with TLS connections.

	// To configure auth via a URI instead of a Credential, use
	// "mongodb://ldap-user:ldap-pwd@localhost:27017/?authMechanism=PLAIN".
	credential := options.Credential{
		AuthMechanism: "PLAIN",
		Username:      "ldap-user",
		Password:      "ldap-pwd",
	}
	clientOpts := options.Client().ApplyURI("mongodb://localhost:27017").SetAuth(credential)

	client, err := mongo.Connect(context.TODO(), clientOpts)
	if err != nil {
		log.Fatal(err)
	}
	_ = client
}

Output:
Example (Ping) 
package main

import (
	"context"
	"log"

	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"go.mongodb.org/mongo-driver/mongo/readpref"
)

func main() {
	// Create a Client to a MongoDB server and use Ping to verify that the server is running.

	clientOpts := options.Client().ApplyURI("mongodb://localhost:27017")
	client, err := mongo.Connect(context.TODO(), clientOpts)
	if err != nil {
		log.Fatal(err)
	}
	defer func() {
		if err = client.Disconnect(context.TODO()); err != nil {
			log.Fatal(err)
		}
	}()

	// Call Ping to verify that the deployment is up and the Client was configured successfully.
	// As mentioned in the Ping documentation, this reduces application resiliency as the server may be
	// temporarily unavailable when Ping is called.
	if err = client.Ping(context.TODO(), readpref.Primary()); err != nil {
		log.Fatal(err)
	}
}

Output:
Example (ReplicaSet) 
package main

import (
	"context"
	"log"

	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	// Create and connect a Client to a replica set deployment.
	// Given this URI, the Go driver will first communicate with localhost:27017 and use the response to discover
	// any other members in the replica set.
	// The URI in this example specifies multiple members of the replica set to increase resiliency as one of the
	// members may be down when the application is started.

	clientOpts := options.Client().ApplyURI("mongodb://localhost:27017,localhost:27018/?replicaSet=replset")
	client, err := mongo.Connect(context.TODO(), clientOpts)
	if err != nil {
		log.Fatal(err)
	}
	_ = client
}

Output:
Example (SCRAM) 
package main

import (
	"context"
	"log"

	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	// Configure a Client with SCRAM authentication (https://docs.mongodb.com/manual/core/security-scram/).
	// The default authentication database for SCRAM is "admin". This can be configured via the
	// authSource query parameter in the URI or the AuthSource field in the options.Credential struct.
	// SCRAM is the default auth mechanism so specifying a mechanism is not required.

	// To configure auth via URI instead of a Credential, use
	// "mongodb://user:password@localhost:27017".
	credential := options.Credential{
		Username: "user",
		Password: "password",
	}
	clientOpts := options.Client().ApplyURI("mongodb://localhost:27017").SetAuth(credential)
	client, err := mongo.Connect(context.TODO(), clientOpts)
	if err != nil {
		log.Fatal(err)
	}
	_ = client
}

Output:
Example (SRV) 
package main

import (
	"context"
	"log"

	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	// Create and connect a Client using an SRV record.
	// SRV records allow administrators to configure a single domain to return a list of host names.
	// The driver will resolve SRV records prefixed with "_mongodb_tcp" and use the returned host names to
	// build its view of the deployment.
	// See https://docs.mongodb.com/manual/reference/connection-string/ for more information about SRV.
	// Full support for SRV records with sharded clusters requires driver version 1.1.0 or higher.

	clientOpts := options.Client().ApplyURI("mongodb+srv://mongodb.example.com")
	client, err := mongo.Connect(context.TODO(), clientOpts)
	if err != nil {
		log.Fatal(err)
	}
	_ = client
}

Output:
Example (Sharded) 
package main

import (
	"context"
	"log"

	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	// Create and connect a Client to a sharded deployment.
	// The URI for a sharded deployment should specify the mongos servers that the application wants to send
	// messages to.

	clientOpts := options.Client().ApplyURI("mongodb://localhost:27017,localhost:27018")
	client, err := mongo.Connect(context.TODO(), clientOpts)
	if err != nil {
		log.Fatal(err)
	}
	_ = client
}

Output:
Example (X509) 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	// Configure a Client with X509 authentication (https://docs.mongodb.com/manual/core/security-x.509/).

	// X509 can be configured with different sets of options in the connection string:
	// 1. tlsCAFile (or SslCertificateAuthorityFile): Path to the file with either a single or bundle of certificate
	// authorities to be considered trusted when making a TLS connection.
	// 2. tlsCertificateKeyFile (or SslClientCertificateKeyFile): Path to the client certificate file or the client
	// private key file. In the case that both are needed, the files should be concatenated.

	// The SetAuth client option should also be used. The username field is optional. If it is not specified, it will
	// be extracted from the certificate key file. The AuthSource is required to be $external.

	caFilePath := "path/to/cafile"
	certificateKeyFilePath := "path/to/client-certificate"

	// To configure auth via a URI instead of a Credential, append "&authMechanism=MONGODB-X509" to the URI.
	uri := "mongodb://host:port/?tlsCAFile=%s&tlsCertificateKeyFile=%s"
	uri = fmt.Sprintf(uri, caFilePath, certificateKeyFilePath)
	credential := options.Credential{
		AuthMechanism: "MONGODB-X509",
	}
	clientOpts := options.Client().ApplyURI(uri).SetAuth(credential)

	client, err := mongo.Connect(context.TODO(), clientOpts)
	if err != nil {
		log.Fatal(err)
	}
	_ = client
}

Output:

func NewClient 

func NewClient(opts ...*options.ClientOptions) (*Client, error)

NewClient creates a new client to connect to a deployment specified by the uri.

When creating an options.ClientOptions, the order the methods are called matters. Later Set* methods will overwrite the values from previous Set* method invocations. This includes the ApplyURI method. This allows callers to determine the order of precedence for option application. For instance, if ApplyURI is called before SetAuth, the Credential from SetAuth will overwrite the values from the connection string. If ApplyURI is called after SetAuth, then its values will overwrite those from SetAuth.

The opts parameter is processed using options.MergeClientOptions, which will overwrite entire option fields of previous options, there is no partial overwriting. For example, if Username is set in the Auth field for the first option, and Password is set for the second but with no Username, after the merge the Username field will be empty.

func (*Client) Connect added in v0.0.3 

func (c *Client) Connect(ctx context.Context) error

Connect initializes the Client by starting background monitoring goroutines. If the Client was created using the NewClient function, this method must be called before a Client can be used.

Connect starts background goroutines to monitor the state of the deployment and does not do any I/O in the main goroutine. The Client.Ping method can be used to verify that the connection was created successfully.

func (*Client) Database 

func (c *Client) Database(name string, opts ...*options.DatabaseOptions) *Database

Database returns a handle for a database with the given name configured with the given DatabaseOptions.

func (*Client) Disconnect added in v0.0.3 

func (c *Client) Disconnect(ctx context.Context) error

Disconnect closes sockets to the topology referenced by this Client. It will shut down any monitoring goroutines, close the idle connection pool, and will wait until all the in use connections have been returned to the connection pool and closed before returning. If the context expires via cancellation, deadline, or timeout before the in use connections have returned, the in use connections will be closed, resulting in the failure of any in flight read or write operations. If this method returns with no errors, all connections associated with this Client have been closed.

func (*Client) ListDatabaseNames added in v0.0.3 

func (c *Client) ListDatabaseNames(ctx context.Context, filter interface{}, opts ...*options.ListDatabasesOptions) ([]string, error)

ListDatabaseNames executes a listDatabases command and returns a slice containing the names of all of the databases on the server.

The filter parameter must be a document containing query operators and can be used to select which databases are included in the result. It cannot be nil. An empty document (e.g. bson.D{}) should be used to include all databases.

The opts parameter can be used to specify options for this operation (see the options.ListDatabasesOptions documentation.)

For more information about the command, see https://docs.mongodb.com/manual/reference/command/listDatabases/.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
)

func main() {
	var client *mongo.Client

	// use a filter to only select non-empty databases
	result, err := client.ListDatabaseNames(context.TODO(), bson.D{{"empty", false}})
	if err != nil {
		log.Fatal(err)
	}

	for _, db := range result {
		fmt.Println(db)
	}
}

Output:

func (*Client) ListDatabases added in v0.0.3 

func (c *Client) ListDatabases(ctx context.Context, filter interface{}, opts ...*options.ListDatabasesOptions) (ListDatabasesResult, error)

ListDatabases executes a listDatabases command and returns the result.

The filter parameter must be a document containing query operators and can be used to select which databases are included in the result. It cannot be nil. An empty document (e.g. bson.D{}) should be used to include all databases.

The opts paramter can be used to specify options for this operation (see the options.ListDatabasesOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/listDatabases/.

func (*Client) NumberSessionsInProgress added in v1.2.0 

func (c *Client) NumberSessionsInProgress() int

NumberSessionsInProgress returns the number of sessions that have been started for this client but have not been closed (i.e. EndSession has not been called).

func (*Client) Ping added in v0.0.14 

func (c *Client) Ping(ctx context.Context, rp *readpref.ReadPref) error

Ping sends a ping command to verify that the client can connect to the deployment.

The rp paramter is used to determine which server is selected for the operation. If it is nil, the client's read preference is used.

If the server is down, Ping will try to select a server until the client's server selection timeout expires. This can be configured through the ClientOptions.SetServerSelectionTimeout option when creating a new Client. After the timeout expires, a server selection error is returned.

Using Ping reduces application resilience because applications starting up will error if the server is temporarily unavailable or is failing over (e.g. during autoscaling due to a load spike).

func (*Client) StartSession added in v0.0.10 

func (c *Client) StartSession(opts ...*options.SessionOptions) (Session, error)

StartSession starts a new session configured with the given options.

If the DefaultReadConcern, DefaultWriteConcern, or DefaultReadPreference options are not set, the client's read concern, write concern, or read preference will be used, respectively.

Example (WithTransaction) 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"go.mongodb.org/mongo-driver/mongo/readconcern"
	"go.mongodb.org/mongo-driver/mongo/readpref"
)

func main() {
	var client *mongo.Client // assume client is configured with write concern majority and read preference primary

	// Specify the DefaultReadConcern option so any transactions started through the session will have read concern
	// majority.
	// The DefaultReadPreference and DefaultWriteConcern options aren't specified so they will be inheritied from client
	// and be set to primary and majority, respectively.
	opts := options.Session().SetDefaultReadConcern(readconcern.Majority())
	sess, err := client.StartSession(opts)
	if err != nil {
		log.Fatal(err)
	}
	defer sess.EndSession(context.TODO())

	// Specify the ReadPreference option to set the read preference to primary preferred for this transaction.
	txnOpts := options.Transaction().SetReadPreference(readpref.PrimaryPreferred())
	result, err := sess.WithTransaction(context.TODO(), func(sessCtx mongo.SessionContext) (interface{}, error) {
		// Use sessCtx as the Context parameter for InsertOne and FindOne so both operations are run in a
		// transaction.

		coll := client.Database("db").Collection("coll")
		res, err := coll.InsertOne(sessCtx, bson.D{{"x", 1}})
		if err != nil {
			return nil, err
		}

		var result bson.M
		if err = coll.FindOne(sessCtx, bson.D{{"_id", res.InsertedID}}).Decode(result); err != nil {
			return nil, err
		}
		return result, err
	}, txnOpts)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("result: %v\n", result)
}

Output:

func (*Client) UseSession added in v0.0.16 

func (c *Client) UseSession(ctx context.Context, fn func(SessionContext) error) error

UseSession creates a new Session and uses it to create a new SessionContext, which is used to call the fn callback. The SessionContext parameter must be used as the Context parameter for any operations in the fn callback that should be executed under a session. After the callback returns, the created Session is ended, meaning that any in-progress transactions started by fn will be aborted even if fn returns an error.

If the ctx parameter already contains a Session, that Session will be replaced with the newly created one.

Any error returned by the fn callback will be returned without any modifications.

func (*Client) UseSessionWithOptions added in v0.0.16 

func (c *Client) UseSessionWithOptions(ctx context.Context, opts *options.SessionOptions, fn func(SessionContext) error) error

UseSessionWithOptions operates like UseSession but uses the given SessionOptions to create the Session.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"go.mongodb.org/mongo-driver/mongo/readconcern"
)

func main() {
	var client *mongo.Client

	// Specify the DefaultReadConcern option so any transactions started through the session will have read concern
	// majority.
	// The DefaultReadPreference and DefaultWriteConcern options aren't specified so they will be inheritied from client
	// and be set to primary and majority, respectively.
	opts := options.Session().SetDefaultReadConcern(readconcern.Majority())
	err := client.UseSessionWithOptions(context.TODO(), opts, func(sessCtx mongo.SessionContext) error {
		// Use sessCtx as the Context parameter for InsertOne and FindOne so both operations are run under the new
		// Session.

		if err := sessCtx.StartTransaction(); err != nil {
			return err
		}

		coll := client.Database("db").Collection("coll")
		res, err := coll.InsertOne(sessCtx, bson.D{{"x", 1}})
		if err != nil {
			// Abort the transaction after an error. Use context.Background() to ensure that the abort can complete
			// successfully even if the context passed to mongo.WithSession is changed to have a timeout.
			_ = sessCtx.AbortTransaction(context.Background())
			return err
		}

		var result bson.M
		if err = coll.FindOne(sessCtx, bson.D{{"_id", res.InsertedID}}).Decode(result); err != nil {
			// Abort the transaction after an error. Use context.Background() to ensure that the abort can complete
			// successfully even if the context passed to mongo.WithSession is changed to have a timeout.
			_ = sessCtx.AbortTransaction(context.Background())
			return err
		}
		fmt.Println(result)

		// Use context.Background() to ensure that the commit can complete successfully even if the context passed to
		// mongo.WithSession is changed to have a timeout.
		return sessCtx.CommitTransaction(context.Background())
	})
	if err != nil {
		log.Fatal(err)
	}
}

Output:

func (*Client) Watch added in v0.1.0 

func (c *Client) Watch(ctx context.Context, pipeline interface{},
	opts ...*options.ChangeStreamOptions) (*ChangeStream, error)

Watch returns a change stream for all changes on the deployment. See https://docs.mongodb.com/manual/changeStreams/ for more information about change streams.

The client must be configured with read concern majority or no read concern for a change stream to be created successfully.

The pipeline parameter must be an array of documents, each representing a pipeline stage. The pipeline cannot be nil or empty. The stage documents must all be non-nil. See https://docs.mongodb.com/manual/changeStreams/ for a list of pipeline stages that can be used with change streams. For a pipeline of bson.D documents, the mongo.Pipeline{} type can be used.

The opts parameter can be used to specify options for change stream creation (see the options.ChangeStreamOptions documentation).

Example 
package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var client *mongo.Client

	// specify a pipeline that will only match "insert" events
	// specify the MaxAwaitTimeOption to have each attempt wait two seconds for new documents
	matchStage := bson.D{{"$match", bson.D{{"operationType", "insert"}}}}
	opts := options.ChangeStream().SetMaxAwaitTime(2 * time.Second)
	changeStream, err := client.Watch(context.TODO(), mongo.Pipeline{matchStage}, opts)
	if err != nil {
		log.Fatal(err)
	}

	// print out all change stream events in the order they're received
	// see the mongo.ChangeStream documentation for more examples of using change streams
	for changeStream.Next(context.TODO()) {
		fmt.Println(changeStream.Current)
	}
}

Output:

type ClientEncryption added in v1.2.0 

type ClientEncryption struct {
	// contains filtered or unexported fields
}

ClientEncryption is used to create data keys and explicitly encrypt and decrypt BSON values.

func NewClientEncryption added in v1.2.0 

func NewClientEncryption(keyVaultClient *Client, opts ...*options.ClientEncryptionOptions) (*ClientEncryption, error)

NewClientEncryption creates a new ClientEncryption instance configured with the given options.

func (*ClientEncryption) Close added in v1.2.0 

func (ce *ClientEncryption) Close(ctx context.Context) error

Close cleans up any resources associated with the ClientEncryption instance. This includes disconnecting the key-vault Client instance.

func (*ClientEncryption) CreateDataKey added in v1.2.0 

func (ce *ClientEncryption) CreateDataKey(ctx context.Context, kmsProvider string, opts ...*options.DataKeyOptions) (primitive.Binary, error)

CreateDataKey creates a new key document and inserts it into the key vault collection. Returns the _id of the created document.

func (*ClientEncryption) Decrypt added in v1.2.0 

func (ce *ClientEncryption) Decrypt(ctx context.Context, val primitive.Binary) (bson.RawValue, error)

Decrypt decrypts an encrypted value (BSON binary of subtype 6) and returns the original BSON value.

func (*ClientEncryption) Encrypt added in v1.2.0 

func (ce *ClientEncryption) Encrypt(ctx context.Context, val bson.RawValue, opts ...*options.EncryptOptions) (primitive.Binary, error)

Encrypt encrypts a BSON value with the given key and algorithm. Returns an encrypted value (BSON binary of subtype 6).

type Collection 

type Collection struct {
	// contains filtered or unexported fields
}

Collection is a handle to a MongoDB collection. It is safe for concurrent use by multiple goroutines.

func (*Collection) Aggregate 

func (coll *Collection) Aggregate(ctx context.Context, pipeline interface{},
	opts ...*options.AggregateOptions) (*Cursor, error)

Aggregate executes an aggregate command against the collection and returns a cursor over the resulting documents.

The pipeline parameter must be an array of documents, each representing an aggregation stage. The pipeline cannot be nil but can be empty. The stage documents must all be non-nil. For a pipeline of bson.D documents, the mongo.Pipeline type can be used. See https://docs.mongodb.com/manual/reference/operator/aggregation-pipeline/#db-collection-aggregate-stages for a list of valid stages in aggregations.

The opts parameter can be used to specify options for the operation (see the options.AggregateOptions documentation.)

For more information about the command, see https://docs.mongodb.com/manual/reference/command/aggregate/.

Example 
package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var coll *mongo.Collection

	// specify a pipeline that will return the number of times each name appears in the collection
	// specify the MaxTime option to limit the amount of time the operation can run on the server
	groupStage := bson.D{
		{"$group", bson.D{
			{"_id", "$name"},
			{"numTimes", bson.D{
				{"$sum", 1},
			}},
		}},
	}
	opts := options.Aggregate().SetMaxTime(2 * time.Second)
	cursor, err := coll.Aggregate(context.TODO(), mongo.Pipeline{groupStage}, opts)
	if err != nil {
		log.Fatal(err)
	}

	// get a list of all returned documents and print them out
	// see the mongo.Cursor documentation for more examples of using cursors
	var results []bson.M
	if err = cursor.All(context.TODO(), &results); err != nil {
		log.Fatal(err)
	}
	for _, result := range results {
		fmt.Printf("name %v appears %v times\n", result["_id"], result["numTimes"])
	}
}

Output:

func (*Collection) BulkWrite added in v0.0.16 

func (coll *Collection) BulkWrite(ctx context.Context, models []WriteModel,
	opts ...*options.BulkWriteOptions) (*BulkWriteResult, error)

BulkWrite performs a bulk write operation (https://docs.mongodb.com/manual/core/bulk-write-operations/).

The models parameter must be a slice of operations to be executed in this bulk write. It cannot be nil or empty. All of the models must be non-nil. See the mongo.WriteModel documentation for a list of valid model types and examples of how they should be used.

The opts parameter can be used to specify options for the operation (see the options.BulkWriteOptions documentation.)

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/bson/primitive"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var coll *mongo.Collection
	var firstID, secondID primitive.ObjectID

	// update the "email" field for two users
	// for each update, specify the Upsert option to insert a new document if a document matching the filter isn't
	// found
	// set the Ordered option to false to allow both operations to happen even if one of them errors
	firstUpdate := bson.D{{"$set", bson.D{{"email", "firstEmail@example.com"}}}}
	secondUpdate := bson.D{{"$set", bson.D{{"email", "secondEmail@example.com"}}}}
	models := []mongo.WriteModel{
		mongo.NewUpdateOneModel().SetFilter(bson.D{{"_id", firstID}}).SetUpdate(firstUpdate).SetUpsert(true),
		mongo.NewUpdateOneModel().SetFilter(bson.D{{"_id", secondID}}).SetUpdate(secondUpdate).SetUpsert(true),
	}
	opts := options.BulkWrite().SetOrdered(false)
	res, err := coll.BulkWrite(context.TODO(), models, opts)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("inserted %v and deleted %v documents\n", res.InsertedCount, res.DeletedCount)
}

Output:

func (*Collection) Clone added in v0.0.9 

func (coll *Collection) Clone(opts ...*options.CollectionOptions) (*Collection, error)

Clone creates a copy of the Collection configured with the given CollectionOptions. The specified options are merged with the existing options on the collection, with the specified options taking precedence.

func (*Collection) CountDocuments added in v0.0.11 

func (coll *Collection) CountDocuments(ctx context.Context, filter interface{},
	opts ...*options.CountOptions) (int64, error)

CountDocuments returns the number of documents in the collection. For a fast count of the documents in the collection, see the EstimatedDocumentCount method.

The filter parameter must be a document and can be used to select which documents contribute to the count. It cannot be nil. An empty document (e.g. bson.D{}) should be used to count all documents in the collection. This will result in a full collection scan.

The opts parameter can be used to specify options for the operation (see the options.CountOptions documentation).

Example 
package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var coll *mongo.Collection

	// count the number of times the name "Bob" appears in the collection
	// specify the MaxTime option to limit the amount of time the operation can run on the server
	opts := options.Count().SetMaxTime(2 * time.Second)
	count, err := coll.CountDocuments(context.TODO(), bson.D{{"name", "Bob"}}, opts)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("name Bob appears in %v documents", count)
}

Output:

func (*Collection) Database added in v0.0.15 

func (coll *Collection) Database() *Database

Database returns the Database that was used to create the Collection.

func (*Collection) DeleteMany 

func (coll *Collection) DeleteMany(ctx context.Context, filter interface{},
	opts ...*options.DeleteOptions) (*DeleteResult, error)

DeleteMany executes a delete command to delete documents from the collection.

The filter parameter must be a document containing query operators and can be used to select the documents to be deleted. It cannot be nil. An empty document (e.g. bson.D{}) should be used to delete all documents in the collection. If the filter does not match any documents, the operation will succeed and a DeleteResult with a DeletedCount of 0 will be returned.

The opts parameter can be used to specify options for the operation (see the options.DeleteOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/delete/.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var coll *mongo.Collection

	// delete all documents in which the "name" field is "Bob" or "bob"
	// specify the Collation option to provide a collation that will ignore case for string comparisons
	opts := options.Delete().SetCollation(&options.Collation{
		Locale:    "en_US",
		Strength:  1,
		CaseLevel: false,
	})
	res, err := coll.DeleteMany(context.TODO(), bson.D{{"name", "bob"}}, opts)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("deleted %v documents\n", res.DeletedCount)
}

Output:

func (*Collection) DeleteOne 

func (coll *Collection) DeleteOne(ctx context.Context, filter interface{},
	opts ...*options.DeleteOptions) (*DeleteResult, error)

DeleteOne executes a delete command to delete at most one document from the collection.

The filter parameter must be a document containing query operators and can be used to select the document to be deleted. It cannot be nil. If the filter does not match any documents, the operation will succeed and a DeleteResult with a DeletedCount of 0 will be returned. If the filter matches multiple documents, one will be selected from the matched set.

The opts parameter can be used to specify options for the operation (see the options.DeleteOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/delete/.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var coll *mongo.Collection

	// delete at most one document in which the "name" field is "Bob" or "bob"
	// specify the SetCollation option to provide a collation that will ignore case for string comparisons
	opts := options.Delete().SetCollation(&options.Collation{
		Locale:    "en_US",
		Strength:  1,
		CaseLevel: false,
	})
	res, err := coll.DeleteOne(context.TODO(), bson.D{{"name", "bob"}}, opts)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("deleted %v documents\n", res.DeletedCount)
}

Output:

func (*Collection) Distinct 

func (coll *Collection) Distinct(ctx context.Context, fieldName string, filter interface{},
	opts ...*options.DistinctOptions) ([]interface{}, error)

Distinct executes a distinct command to find the unique values for a specified field in the collection.

The fieldName parameter specifies the field name for which distinct values should be returned.

The filter parameter must be a document containing query operators and can be used to select which documents are considered. It cannot be nil. An empty document (e.g. bson.D{}) should be used to select all documents.

The opts parameter can be used to specify options for the operation (see the options.DistinctOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/distinct/.

Example 
package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var coll *mongo.Collection

	// find all unique values for the "name" field for documents in which the "age" field is greater than 25
	// specify the MaxTime option to limit the amount of time the operation can run on the server
	filter := bson.D{{"age", bson.D{{"$gt", 25}}}}
	opts := options.Distinct().SetMaxTime(2 * time.Second)
	values, err := coll.Distinct(context.TODO(), "name", filter, opts)
	if err != nil {
		log.Fatal(err)
	}

	for _, value := range values {
		fmt.Println(value)
	}
}

Output:

func (*Collection) Drop added in v0.0.4 

func (coll *Collection) Drop(ctx context.Context) error

Drop drops the collection on the server. This method ignores "namespace not found" errors so it is safe to drop a collection that does not exist on the server.

func (*Collection) EstimatedDocumentCount added in v0.0.11 

func (coll *Collection) EstimatedDocumentCount(ctx context.Context,
	opts ...*options.EstimatedDocumentCountOptions) (int64, error)

EstimatedDocumentCount executes a count command and returns an estimate of the number of documents in the collection using collection metadata.

The opts parameter can be used to specify options for the operation (see the options.EstimatedDocumentCountOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/count/.

Example 
package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var coll *mongo.Collection

	// get and print an estimated of the number of documents in the collection
	// specify the MaxTime option to limit the amount of time the operation can run on the server
	opts := options.EstimatedDocumentCount().SetMaxTime(2 * time.Second)
	count, err := coll.EstimatedDocumentCount(context.TODO(), opts)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("estimated document count: %v", count)
}

Output:

func (*Collection) Find 

func (coll *Collection) Find(ctx context.Context, filter interface{},
	opts ...*options.FindOptions) (*Cursor, error)

Find executes a find command and returns a Cursor over the matching documents in the collection.

The filter parameter must be a document containing query operators and can be used to select which documents are included in the result. It cannot be nil. An empty document (e.g. bson.D{}) should be used to include all documents.

The opts parameter can be used to specify options for the operation (see the options.FindOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/find/.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var coll *mongo.Collection

	// find all documents in which the "name" field is "Bob"
	// specify the Sort option to sort the returned documents by age in ascending order
	opts := options.Find().SetSort(bson.D{{"age", 1}})
	cursor, err := coll.Find(context.TODO(), bson.D{{"name", "Bob"}}, opts)
	if err != nil {
		log.Fatal(err)
	}

	// get a list of all returned documents and print them out
	// see the mongo.Cursor documentation for more examples of using cursors
	var results []bson.M
	if err = cursor.All(context.TODO(), &results); err != nil {
		log.Fatal(err)
	}
	for _, result := range results {
		fmt.Println(result)
	}
}

Output:

func (*Collection) FindOne 

func (coll *Collection) FindOne(ctx context.Context, filter interface{},
	opts ...*options.FindOneOptions) *SingleResult

FindOne executes a find command and returns a SingleResult for one document in the collection.

The filter parameter must be a document containing query operators and can be used to select the document to be returned. It cannot be nil. If the filter does not match any documents, a SingleResult with an error set to ErrNoDocuments will be returned. If the filter matches multiple documents, one will be selected from the matched set.

The opts parameter can be used to specify options for this operation (see the options.FindOneOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/find/.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/bson/primitive"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var coll *mongo.Collection
	var id primitive.ObjectID

	// find the document for which the _id field matches id
	// specify the Sort option to sort the documents by age
	// the first document in the sorted order will be returned
	opts := options.FindOne().SetSort(bson.D{{"age", 1}})
	var result bson.M
	err := coll.FindOne(context.TODO(), bson.D{{"_id", id}}, opts).Decode(&result)
	if err != nil {
		// ErrNoDocuments means that the filter did not match any documents in the collection
		if err == mongo.ErrNoDocuments {
			return
		}
		log.Fatal(err)
	}
	fmt.Printf("found document %v", result)
}

Output:

func (*Collection) FindOneAndDelete 

func (coll *Collection) FindOneAndDelete(ctx context.Context, filter interface{},
	opts ...*options.FindOneAndDeleteOptions) *SingleResult

FindOneAndDelete executes a findAndModify command to delete at most one document in the collection. and returns the document as it appeared before deletion.

The filter parameter must be a document containing query operators and can be used to select the document to be deleted. It cannot be nil. If the filter does not match any documents, a SingleResult with an error set to ErrNoDocuments wil be returned. If the filter matches multiple documents, one will be selected from the matched set.

The opts parameter can be used to specify options for the operation (see the options.FindOneAndDeleteOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/findAndModify/.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/bson/primitive"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var coll *mongo.Collection
	var id primitive.ObjectID

	// find and delete the document for which the _id field matches id
	// specify the Projection option to only include the name and age fields in the returned document
	opts := options.FindOneAndDelete().SetProjection(bson.D{{"name", 1}, {"age", 1}})
	var deletedDocument bson.M
	err := coll.FindOneAndDelete(context.TODO(), bson.D{{"_id", id}}, opts).Decode(&deletedDocument)
	if err != nil {
		// ErrNoDocuments means that the filter did not match any documents in the collection
		if err == mongo.ErrNoDocuments {
			return
		}
		log.Fatal(err)
	}
	fmt.Printf("deleted document %v", deletedDocument)
}

Output:

func (*Collection) FindOneAndReplace 

func (coll *Collection) FindOneAndReplace(ctx context.Context, filter interface{},
	replacement interface{}, opts ...*options.FindOneAndReplaceOptions) *SingleResult

FindOneAndReplace executes a findAndModify command to replace at most one document in the collection and returns the document as it appeared before replacement.

The filter parameter must be a document containing query operators and can be used to select the document to be replaced. It cannot be nil. If the filter does not match any documents, a SingleResult with an error set to ErrNoDocuments wil be returned. If the filter matches multiple documents, one will be selected from the matched set.

The replacement parameter must be a document that will be used to replace the selected document. It cannot be nil and cannot contain any update operators (https://docs.mongodb.com/manual/reference/operator/update/).

The opts parameter can be used to specify options for the operation (see the options.FindOneAndReplaceOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/findAndModify/.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/bson/primitive"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var coll *mongo.Collection
	var id primitive.ObjectID

	// find the document for which the _id field matches id and add a field called "location"
	// specify the Upsert option to insert a new document if a document matching the filter isn't found
	opts := options.FindOneAndReplace().SetUpsert(true)
	filter := bson.D{{"_id", id}}
	replacement := bson.D{{"location", "NYC"}}
	var replacedDocument bson.M
	err := coll.FindOneAndReplace(context.TODO(), filter, replacement, opts).Decode(&replacedDocument)
	if err != nil {
		// ErrNoDocuments means that the filter did not match any documents in the collection
		if err == mongo.ErrNoDocuments {
			return
		}
		log.Fatal(err)
	}
	fmt.Printf("replaced document %v", replacedDocument)
}

Output:

func (*Collection) FindOneAndUpdate 

func (coll *Collection) FindOneAndUpdate(ctx context.Context, filter interface{},
	update interface{}, opts ...*options.FindOneAndUpdateOptions) *SingleResult

FindOneAndUpdate executes a findAndModify command to update at most one document in the collection and returns the document as it appeared before updating.

The filter parameter must be a document containing query operators and can be used to select the document to be updated. It cannot be nil. If the filter does not match any documents, a SingleResult with an error set to ErrNoDocuments wil be returned. If the filter matches multiple documents, one will be selected from the matched set.

The update parameter must be a document containing update operators (https://docs.mongodb.com/manual/reference/operator/update/) and can be used to specify the modifications to be made to the selected document. It cannot be nil or empty.

The opts parameter can be used to specify options for the operation (see the options.FindOneAndUpdateOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/findAndModify/.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/bson/primitive"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var coll *mongo.Collection
	var id primitive.ObjectID

	// find the document for which the _id field matches id and set the email to "newemail@example.com"
	// specify the Upsert option to insert a new document if a document matching the filter isn't found
	opts := options.FindOneAndUpdate().SetUpsert(true)
	filter := bson.D{{"_id", id}}
	update := bson.D{{"$set", bson.D{{"email", "newemail@example.com"}}}}
	var updatedDocument bson.M
	err := coll.FindOneAndUpdate(context.TODO(), filter, update, opts).Decode(&updatedDocument)
	if err != nil {
		// ErrNoDocuments means that the filter did not match any documents in the collection
		if err == mongo.ErrNoDocuments {
			return
		}
		log.Fatal(err)
	}
	fmt.Printf("updated document %v", updatedDocument)
}

Output:

func (*Collection) Indexes added in v0.0.3 

func (coll *Collection) Indexes() IndexView

Indexes returns an IndexView instance that can be used to perform operations on the indexes for the collection.

func (*Collection) InsertMany 

func (coll *Collection) InsertMany(ctx context.Context, documents []interface{},
	opts ...*options.InsertManyOptions) (*InsertManyResult, error)

InsertMany executes an insert command to insert multiple documents into the collection. If write errors occur during the operation (e.g. duplicate key error), this method returns a BulkWriteException error.

The documents parameter must be a slice of documents to insert. The slice cannot be nil or empty. The elements must all be non-nil. For any document that does not have an _id field when transformed into BSON, one will be added automatically to the marshalled document. The original document will not be modified. The _id values for the inserted documents can be retrieved from the InsertedIDs field of the returnd InsertManyResult.

The opts parameter can be used to specify options for the operation (see the options.InsertManyOptions documentation.)

For more information about the command, see https://docs.mongodb.com/manual/reference/command/insert/.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var coll *mongo.Collection

	// insert documents {name: "Alice"} and {name: "Bob"}
	// set the Ordered option to false to allow both operations to happen even if one of them errors
	docs := []interface{}{
		bson.D{{"name", "Alice"}},
		bson.D{{"name", "Bob"}},
	}
	opts := options.InsertMany().SetOrdered(false)
	res, err := coll.InsertMany(context.TODO(), docs, opts)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("inserted documents with IDs %v\n", res.InsertedIDs)
}

Output:

func (*Collection) InsertOne 

func (coll *Collection) InsertOne(ctx context.Context, document interface{},
	opts ...*options.InsertOneOptions) (*InsertOneResult, error)

InsertOne executes an insert command to insert a single document into the collection.

The document parameter must be the document to be inserted. It cannot be nil. If the document does not have an _id field when transformed into BSON, one will be added automatically to the marshalled document. The original document will not be modified. The _id can be retrieved from the InsertedID field of the returned InsertOneResult.

The opts parameter can be used to specify options for the operation (see the options.InsertOneOptions documentation.)

For more information about the command, see https://docs.mongodb.com/manual/reference/command/insert/.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
)

func main() {
	var coll *mongo.Collection

	// insert the document {name: "Alice"}
	res, err := coll.InsertOne(context.TODO(), bson.D{{"name", "Alice"}})
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("inserted document with ID %v\n", res.InsertedID)
}

Output:

func (*Collection) Name added in v0.0.4 

func (coll *Collection) Name() string

Name returns the name of the collection.

func (*Collection) ReplaceOne 

func (coll *Collection) ReplaceOne(ctx context.Context, filter interface{},
	replacement interface{}, opts ...*options.ReplaceOptions) (*UpdateResult, error)

ReplaceOne executes an update command to replace at most one document in the collection.

The filter parameter must be a document containing query operators and can be used to select the document to be replaced. It cannot be nil. If the filter does not match any documents, the operation will succeed and an UpdateResult with a MatchedCount of 0 will be returned. If the filter matches multiple documents, one will be selected from the matched set and MatchedCount will equal 1.

The replacement parameter must be a document that will be used to replace the selected document. It cannot be nil and cannot contain any update operators (https://docs.mongodb.com/manual/reference/operator/update/).

The opts parameter can be used to specify options for the operation (see the options.ReplaceOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/update/.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/bson/primitive"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var coll *mongo.Collection
	var id primitive.ObjectID

	// find the document for which the _id field matches id and add a field called "location"
	// specify the Upsert option to insert a new document if a document matching the filter isn't found
	opts := options.Replace().SetUpsert(true)
	filter := bson.D{{"_id", id}}
	replacement := bson.D{{"location", "NYC"}}
	result, err := coll.ReplaceOne(context.TODO(), filter, replacement, opts)
	if err != nil {
		log.Fatal(err)
	}

	if result.MatchedCount != 0 {
		fmt.Println("matched and replaced an existing document")
		return
	}
	if result.UpsertedCount != 0 {
		fmt.Printf("inserted a new document with ID %v\n", result.UpsertedID)
	}
}

Output:

func (*Collection) UpdateMany 

func (coll *Collection) UpdateMany(ctx context.Context, filter interface{}, update interface{},
	opts ...*options.UpdateOptions) (*UpdateResult, error)

UpdateMany executes an update command to update documents in the collection.

The filter parameter must be a document containing query operators and can be used to select the documents to be updated. It cannot be nil. If the filter does not match any documents, the operation will succeed and an UpdateResult with a MatchedCount of 0 will be returned.

The update parameter must be a document containing update operators (https://docs.mongodb.com/manual/reference/operator/update/) and can be used to specify the modifications to be made to the selected documents. It cannot be nil or empty.

The opts parameter can be used to specify options for the operation (see the options.UpdateOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/update/.

Example 
package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
)

func main() {
	var coll *mongo.Collection

	// increment the age for all users whose birthday is today
	today := time.Now().Format("01-01-1970")
	filter := bson.D{{"birthday", today}}
	update := bson.D{{"$inc", bson.D{{"age", 1}}}}

	result, err := coll.UpdateMany(context.TODO(), filter, update)
	if err != nil {
		log.Fatal(err)
	}

	if result.MatchedCount != 0 {
		fmt.Println("matched and replaced an existing document")
		return
	}
}

Output:

func (*Collection) UpdateOne 

func (coll *Collection) UpdateOne(ctx context.Context, filter interface{}, update interface{},
	opts ...*options.UpdateOptions) (*UpdateResult, error)

UpdateOne executes an update command to update at most one document in the collection.

The filter parameter must be a document containing query operators and can be used to select the document to be updated. It cannot be nil. If the filter does not match any documents, the operation will succeed and an UpdateResult with a MatchedCount of 0 will be returned. If the filter matches multiple documents, one will be selected from the matched set and MatchedCount will equal 1.

The update parameter must be a document containing update operators (https://docs.mongodb.com/manual/reference/operator/update/) and can be used to specify the modifications to be made to the selected document. It cannot be nil or empty.

The opts parameter can be used to specify options for the operation (see the options.UpdateOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/update/.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/bson/primitive"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var coll *mongo.Collection
	var id primitive.ObjectID

	// find the document for which the _id field matches id and set the email to "newemail@example.com"
	// specify the Upsert option to insert a new document if a document matching the filter isn't found
	opts := options.Update().SetUpsert(true)
	filter := bson.D{{"_id", id}}
	update := bson.D{{"$set", bson.D{{"email", "newemail@example.com"}}}}

	result, err := coll.UpdateOne(context.TODO(), filter, update, opts)
	if err != nil {
		log.Fatal(err)
	}

	if result.MatchedCount != 0 {
		fmt.Println("matched and replaced an existing document")
		return
	}
	if result.UpsertedCount != 0 {
		fmt.Printf("inserted a new document with ID %v\n", result.UpsertedID)
	}
}

Output:

func (*Collection) Watch added in v0.0.2 

func (coll *Collection) Watch(ctx context.Context, pipeline interface{},
	opts ...*options.ChangeStreamOptions) (*ChangeStream, error)

Watch returns a change stream for all changes on the corresponding collection. See https://docs.mongodb.com/manual/changeStreams/ for more information about change streams.

The Collection must be configured with read concern majority or no read concern for a change stream to be created successfully.

The pipeline parameter must be an array of documents, each representing a pipeline stage. The pipeline cannot be nil but can be empty. The stage documents must all be non-nil. See https://docs.mongodb.com/manual/changeStreams/ for a list of pipeline stages that can be used with change streams. For a pipeline of bson.D documents, the mongo.Pipeline{} type can be used.

The opts parameter can be used to specify options for change stream creation (see the options.ChangeStreamOptions documentation).

Example 
package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var collection *mongo.Collection

	// specify a pipeline that will only match "insert" events
	// specify the MaxAwaitTimeOption to have each attempt wait two seconds for new documents
	matchStage := bson.D{{"$match", bson.D{{"operationType", "insert"}}}}
	opts := options.ChangeStream().SetMaxAwaitTime(2 * time.Second)
	changeStream, err := collection.Watch(context.TODO(), mongo.Pipeline{matchStage}, opts)
	if err != nil {
		log.Fatal(err)
	}

	// print out all change stream events in the order they're received
	// see the mongo.ChangeStream documentation for more examples of using change streams
	for changeStream.Next(context.TODO()) {
		fmt.Println(changeStream.Current)
	}
}

Output:

type CommandError added in v1.0.0 

type CommandError struct {
	Code    int32
	Message string
	Labels  []string // Categories to which the error belongs
	Name    string   // A human-readable name corresponding to the error code
	Wrapped error    // The underlying error, if one exists.
}

CommandError represents a server error during execution of a command. This can be returned by any operation.

func (CommandError) Error added in v1.0.0 

func (e CommandError) Error() string

Error implements the error interface.

func (CommandError) HasErrorLabel added in v1.0.0 

func (e CommandError) HasErrorLabel(label string) bool

HasErrorLabel returns true if the error contains the specified label.

func (CommandError) IsMaxTimeMSExpiredError added in v1.1.0 

func (e CommandError) IsMaxTimeMSExpiredError() bool

IsMaxTimeMSExpiredError returns true if the error is a MaxTimeMSExpired error.

func (CommandError) Unwrap added in v1.4.0 

func (e CommandError) Unwrap() error

Unwrap returns the underlying error.

type Cursor 

type Cursor struct {
	// Current contains the BSON bytes of the current change document. This property is only valid until the next call
	// to Next or TryNext. If continued access is required, a copy must be made.
	Current bson.Raw
	// contains filtered or unexported fields
}

Cursor is used to iterate over a stream of documents. Each document can be decoded into a Go type via the Decode method or accessed as raw BSON via the Current field.

func (*Cursor) All added in v1.1.0 

func (c *Cursor) All(ctx context.Context, results interface{}) error

All iterates the cursor and decodes each document into results. The results parameter must be a pointer to a slice. The slice pointed to by results will be completely overwritten. This method will close the cursor after retrieving all documents. If the cursor has been iterated, any previously iterated documents will not be included in results.

This method requires driver version >= 1.1.0.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
)

func main() {
	var cursor *mongo.Cursor

	var results []bson.M
	if err := cursor.All(context.TODO(), &results); err != nil {
		log.Fatal(err)
	}
	fmt.Println(results)
}

Output:

func (*Cursor) Close added in v0.0.2 

func (c *Cursor) Close(ctx context.Context) error

Close closes this cursor. Next and TryNext must not be called after Close has been called. Close is idempotent. After the first call, any subsequent calls will not change the state.

func (*Cursor) Decode added in v0.0.2 

func (c *Cursor) Decode(val interface{}) error

Decode will unmarshal the current document into val and return any errors from the unmarshalling process without any modification. If val is nil or is a typed nil, an error will be returned.

func (*Cursor) Err added in v0.0.2 

func (c *Cursor) Err() error

Err returns the last error seen by the Cursor, or nil if no error has occurred.

func (*Cursor) ID added in v0.0.2 

func (c *Cursor) ID() int64

ID returns the ID of this cursor, or 0 if the cursor has been closed or exhausted.

func (*Cursor) Next added in v0.0.2 

func (c *Cursor) Next(ctx context.Context) bool

Next gets the next document for this cursor. It returns true if there were no errors and the cursor has not been exhausted.

Next blocks until a document is available, an error occurs, or ctx expires. If ctx expires, the error will be set to ctx.Err(). In an error case, Next will return false.

If Next returns false, subsequent calls will also return false.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
)

func main() {
	var cursor *mongo.Cursor
	defer cursor.Close(context.TODO())

	// Iterate the cursor and print out each document until the cursor is exhausted or there is an error getting the
	// next document.
	for cursor.Next(context.TODO()) {
		// A new result variable should be declared for each document.
		var result bson.M
		if err := cursor.Decode(&result); err != nil {
			log.Fatal(err)
		}
		fmt.Println(result)
	}
	if err := cursor.Err(); err != nil {
		log.Fatal(err)
	}
}

Output:

func (*Cursor) RemainingBatchLength added in v1.4.0 

func (c *Cursor) RemainingBatchLength() int

RemainingBatchLength returns the number of documents left in the current batch. If this returns zero, the subsequent call to Next or TryNext will do a network request to fetch the next batch.

Example 
package main

import (
	"context"
	"fmt"
	"time"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	// Because we're using a tailable cursor, this must be a handle to a capped collection.
	var coll *mongo.Collection

	// Create a tailable await cursor. Specify the MaxAwaitTime option so requests to get more data will return if there
	// are no documents available after two seconds.
	findOpts := options.Find().
		SetCursorType(options.TailableAwait).
		SetMaxAwaitTime(2 * time.Second)
	cursor, err := coll.Find(context.TODO(), bson.D{}, findOpts)
	if err != nil {
		panic(err)
	}

	for {
		// Iterate the cursor using TryNext.
		if cursor.TryNext(context.TODO()) {
			fmt.Println(cursor.Current)
		}

		// Handle cursor errors or the cursor being closed by the server.
		if err = cursor.Err(); err != nil {
			panic(err)
		}
		if cursor.ID() == 0 {
			panic("cursor was unexpectedly closed by the server")
		}

		// Use the RemainingBatchLength function to rate-limit the number of network requests the driver does. If the
		// current batch is empty, sleep for a short amount of time to let documents build up on the server before
		// the next TryNext call, which will do a network request.
		if cursor.RemainingBatchLength() == 0 {
			time.Sleep(100 * time.Millisecond)
		}
	}
}

Output:

func (*Cursor) TryNext added in v1.2.0 

func (c *Cursor) TryNext(ctx context.Context) bool

TryNext attempts to get the next document for this cursor. It returns true if there were no errors and the next document is available. This is only recommended for use with tailable cursors as a non-blocking alternative to Next. See https://docs.mongodb.com/manual/core/tailable-cursors/ for more information about tailable cursors.

TryNext returns false if the cursor is exhausted, an error occurs when getting results from the server, the next document is not yet available, or ctx expires. If ctx expires, the error will be set to ctx.Err().

If TryNext returns false and an error occurred or the cursor has been exhausted (i.e. c.Err() != nil || c.ID() == 0), subsequent attempts will also return false. Otherwise, it is safe to call TryNext again until a document is available.

This method requires driver version >= 1.2.0.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
)

func main() {
	var cursor *mongo.Cursor
	defer cursor.Close(context.TODO())

	// Iterate the cursor and print out each document until the cursor is exhausted or there is an error getting the
	// next document.
	for {
		if cursor.TryNext(context.TODO()) {
			// A new result variable should be declared for each document.
			var result bson.M
			if err := cursor.Decode(&result); err != nil {
				log.Fatal(err)
			}
			fmt.Println(result)
			continue
		}

		// If TryNext returns false, the next document is not yet available, the cursor was exhausted and was closed, or
		// an error occured. TryNext should only be called again for the empty batch case.
		if err := cursor.Err(); err != nil {
			log.Fatal(err)
		}
		if cursor.ID() == 0 {
			break
		}
	}
}

Output:

type Database 

type Database struct {
	// contains filtered or unexported fields
}

Database is a handle to a MongoDB database. It is safe for concurrent use by multiple goroutines.

func (*Database) Aggregate added in v1.1.0 

func (db *Database) Aggregate(ctx context.Context, pipeline interface{},
	opts ...*options.AggregateOptions) (*Cursor, error)

Aggregate executes an aggregate command the database. This requires MongoDB version >= 3.6 and driver version >= 1.1.0.

The pipeline parameter must be a slice of documents, each representing an aggregation stage. The pipeline cannot be nil but can be empty. The stage documents must all be non-nil. For a pipeline of bson.D documents, the mongo.Pipeline type can be used. See https://docs.mongodb.com/manual/reference/operator/aggregation-pipeline/#db-aggregate-stages for a list of valid stages in database-level aggregations.

The opts parameter can be used to specify options for this operation (see the options.AggregateOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/aggregate/.

func (*Database) Client 

func (db *Database) Client() *Client

Client returns the Client the Database was created from.

func (*Database) Collection 

func (db *Database) Collection(name string, opts ...*options.CollectionOptions) *Collection

Collection gets a handle for a collection with the given name configured with the given CollectionOptions.

func (*Database) CreateCollection added in v1.4.0 

func (db *Database) CreateCollection(ctx context.Context, name string, opts ...*options.CreateCollectionOptions) error

CreateCollection executes a create command to explicitly create a new collection with the specified name on the server. If the collection being created already exists, this method will return a mongo.CommandError. This method requires driver version 1.4.0 or higher.

The opts parameter can be used to specify options for the operation (see the options.CreateCollectionOptions documentation).

Example 
package main

import (
	"context"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var db *mongo.Database

	// Create a "users" collection with a JSON schema validator. The validator will ensure that each document in the
	// collection has "name" and "age" fields.
	jsonSchema := bson.M{
		"bsonType": "object",
		"required": []string{"name", "age"},
		"properties": bson.M{
			"name": bson.M{
				"bsonType":    "string",
				"description": "the name of the user, which is required and must be a string",
			},
			"age": bson.M{
				"bsonType":    "int",
				"minimum":     18,
				"description": "the age of the user, which is required and must be an integer >= 18",
			},
		},
	}
	validator := bson.M{
		"$jsonSchema": jsonSchema,
	}
	opts := options.CreateCollection().SetValidator(validator)

	if err := db.CreateCollection(context.TODO(), "users", opts); err != nil {
		log.Fatal(err)
	}
}

Output:

func (*Database) CreateView added in v1.4.0 

func (db *Database) CreateView(ctx context.Context, viewName, viewOn string, pipeline interface{},
	opts ...*options.CreateViewOptions) error

CreateView executes a create command to explicitly create a view on the server. See https://docs.mongodb.com/manual/core/views/ for more information about views. This method requires driver version >= 1.4.0 and MongoDB version >= 3.4.

The viewName parameter specifies the name of the view to create.

The viewOn parameter specifies the name of the collection or view on which this view will be created

The pipeline parameter specifies an aggregation pipeline that will be exececuted against the source collection or view to create this view.

The opts parameter can be used to specify options for the operation (see the options.CreateViewOptions documentation).

Example 
package main

import (
	"context"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var db *mongo.Database

	// Create a view on the "users" collection called "usernames". Specify a pipeline that concatenates the "firstName"
	// and "lastName" fields from each document in "users" and projects the result into the "fullName" field in the
	// view.
	projectStage := bson.D{
		{"$project", bson.D{
			{"_id", 0},
			{"fullName", bson.D{
				{"$concat", []string{"$firstName", " ", "$lastName"}},
			}},
		}},
	}
	pipeline := mongo.Pipeline{projectStage}

	// Specify the Collation option to set a default collation for the view.
	opts := options.CreateView().SetCollation(&options.Collation{
		Locale: "en_US",
	})

	if err := db.CreateView(context.TODO(), "usernames", "users", pipeline, opts); err != nil {
		log.Fatal(err)
	}
}

Output:

func (*Database) Drop added in v0.0.4 

func (db *Database) Drop(ctx context.Context) error

Drop drops the database on the server. This method ignores "namespace not found" errors so it is safe to drop a database that does not exist on the server.

func (*Database) ListCollectionNames added in v1.1.0 

func (db *Database) ListCollectionNames(ctx context.Context, filter interface{}, opts ...*options.ListCollectionsOptions) ([]string, error)

ListCollectionNames executes a listCollections command and returns a slice containing the names of the collections in the database. This method requires driver version >= 1.1.0.

The filter parameter must be a document containing query operators and can be used to select which collections are included in the result. It cannot be nil. An empty document (e.g. bson.D{}) should be used to include all collections.

The opts parameter can be used to specify options for the operation (see the options.ListCollectionsOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/listCollections/.

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
)

func main() {
	var db *mongo.Database

	// use a filter to only select capped collections
	result, err := db.ListCollectionNames(context.TODO(), bson.D{{"options.capped", true}})
	if err != nil {
		log.Fatal(err)
	}

	for _, coll := range result {
		fmt.Println(coll)
	}
}

Output:

func (*Database) ListCollections added in v0.0.6 

func (db *Database) ListCollections(ctx context.Context, filter interface{}, opts ...*options.ListCollectionsOptions) (*Cursor, error)

ListCollections executes a listCollections command and returns a cursor over the collections in the database.

The filter parameter must be a document containing query operators and can be used to select which collections are included in the result. It cannot be nil. An empty document (e.g. bson.D{}) should be used to include all collections.

The opts parameter can be used to specify options for the operation (see the options.ListCollectionsOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/listCollections/.

func (*Database) Name 

func (db *Database) Name() string

Name returns the name of the database.

func (*Database) ReadConcern added in v0.0.13 

func (db *Database) ReadConcern() *readconcern.ReadConcern

ReadConcern returns the read concern used to configure the Database object.

func (*Database) ReadPreference added in v0.0.13 

func (db *Database) ReadPreference() *readpref.ReadPref

ReadPreference returns the read preference used to configure the Database object.

func (*Database) RunCommand 

func (db *Database) RunCommand(ctx context.Context, runCommand interface{}, opts ...*options.RunCmdOptions) *SingleResult

RunCommand executes the given command against the database. This function does not obey the Database's read preference. To specify a read preference, the RunCmdOptions.ReadPreference option must be used.

The runCommand parameter must be a document for the command to be executed. It cannot be nil. This must be an order-preserving type such as bson.D. Map types such as bson.M are not valid. If the command document contains a session ID or any transaction-specific fields, the behavior is undefined.

The opts parameter can be used to specify options for this operation (see the options.RunCmdOptions documentation).

Example 
package main

import (
	"context"
	"fmt"
	"log"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"go.mongodb.org/mongo-driver/mongo/readpref"
)

func main() {
	var db *mongo.Database

	// run an explain command to see the query plan for when a "find" is executed on collection "bar"
	// specify the ReadPreference option to explicitly set the read preference to primary
	findCmd := bson.D{{"find", "bar"}}
	command := bson.D{{"explain", findCmd}}
	opts := options.RunCmd().SetReadPreference(readpref.Primary())
	var result bson.M
	if err := db.RunCommand(context.TODO(), command, opts).Decode(&result); err != nil {
		log.Fatal(err)
	}
	fmt.Println(result)
}

Output:

func (*Database) RunCommandCursor added in v0.1.0 

func (db *Database) RunCommandCursor(ctx context.Context, runCommand interface{}, opts ...*options.RunCmdOptions) (*Cursor, error)

RunCommandCursor executes the given command against the database and parses the response as a cursor. If the command being executed does not return a cursor (e.g. insert), the command will be executed on the server and an error will be returned because the server response cannot be parsed as a cursor. This function does not obey the Database's read preference. To specify a read preference, the RunCmdOptions.ReadPreference option must be used.

The runCommand parameter must be a document for the command to be executed. It cannot be nil. This must be an order-preserving type such as bson.D. Map types such as bson.M are not valid. If the command document contains a session ID or any transaction-specific fields, the behavior is undefined.

The opts parameter can be used to specify options for this operation (see the options.RunCmdOptions documentation).

func (*Database) Watch added in v0.1.0 

func (db *Database) Watch(ctx context.Context, pipeline interface{},
	opts ...*options.ChangeStreamOptions) (*ChangeStream, error)

Watch returns a change stream for all changes to the corresponding database. See https://docs.mongodb.com/manual/changeStreams/ for more information about change streams.

The Database must be configured with read concern majority or no read concern for a change stream to be created successfully.

The pipeline parameter must be a slice of documents, each representing a pipeline stage. The pipeline cannot be nil but can be empty. The stage documents must all be non-nil. See https://docs.mongodb.com/manual/changeStreams/ for a list of pipeline stages that can be used with change streams. For a pipeline of bson.D documents, the mongo.Pipeline{} type can be used.

The opts parameter can be used to specify options for change stream creation (see the options.ChangeStreamOptions documentation).

Example 
package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var db *mongo.Database

	// specify a pipeline that will only match "insert" events
	// specify the MaxAwaitTimeOption to have each attempt wait two seconds for new documents
	matchStage := bson.D{{"$match", bson.D{{"operationType", "insert"}}}}
	opts := options.ChangeStream().SetMaxAwaitTime(2 * time.Second)
	changeStream, err := db.Watch(context.TODO(), mongo.Pipeline{matchStage}, opts)
	if err != nil {
		log.Fatal(err)
	}

	// print out all change stream events in the order they're received
	// see the mongo.ChangeStream documentation for more examples of using change streams
	for changeStream.Next(context.TODO()) {
		fmt.Println(changeStream.Current)
	}
}

Output:

func (*Database) WriteConcern added in v0.0.13 

func (db *Database) WriteConcern() *writeconcern.WriteConcern

WriteConcern returns the write concern used to configure the Database object.

type DatabaseSpecification added in v0.0.3 

type DatabaseSpecification struct {
	Name       string // The name of the database.
	SizeOnDisk int64  // The total size of the database files on disk in bytes.
	Empty      bool   // Specfies whether or not the database is empty.
}

DatabaseSpecification contains information for a database. This type is returned as part of ListDatabasesResult.

type DeleteManyModel added in v0.0.16 

type DeleteManyModel struct {
	Filter    interface{}
	Collation *options.Collation
	Hint      interface{}
}

DeleteManyModel is used to delete multiple documents in a BulkWrite operation.

func NewDeleteManyModel added in v0.0.16 

func NewDeleteManyModel() *DeleteManyModel

NewDeleteManyModel creates a new DeleteManyModel.

func (*DeleteManyModel) SetCollation added in v0.3.0 

func (dmm *DeleteManyModel) SetCollation(collation *options.Collation) *DeleteManyModel

SetCollation specifies a collation to use for string comparisons. The default is nil, meaning no collation will be used.

func (*DeleteManyModel) SetFilter added in v0.3.0 

func (dmm *DeleteManyModel) SetFilter(filter interface{}) *DeleteManyModel

SetFilter specifies a filter to use to select documents to delete. The filter must be a document containing query operators. It cannot be nil.

func (*DeleteManyModel) SetHint added in v1.4.0 

func (dmm *DeleteManyModel) SetHint(hint interface{}) *DeleteManyModel

SetHint specifies the index to use for the operation. This should either be the index name as a string or the index specification as a document. This option is only valid for MongoDB versions >= 4.4. Server versions >= 3.4 will return an error if this option is specified. For server versions < 3.4, the driver will return a client-side error if this option is specified. The driver will return an error if this option is specified during an unacknowledged write operation. The default value is nil, which means that no hint will be sent.

type DeleteOneModel added in v0.0.16 

type DeleteOneModel struct {
	Filter    interface{}
	Collation *options.Collation
	Hint      interface{}
}

DeleteOneModel is used to delete at most one document in a BulkWriteOperation.

func NewDeleteOneModel added in v0.0.16 

func NewDeleteOneModel() *DeleteOneModel

NewDeleteOneModel creates a new DeleteOneModel.

func (*DeleteOneModel) SetCollation added in v0.3.0 

func (dom *DeleteOneModel) SetCollation(collation *options.Collation) *DeleteOneModel

SetCollation specifies a collation to use for string comparisons. The default is nil, meaning no collation will be used.

func (*DeleteOneModel) SetFilter added in v0.3.0 

func (dom *DeleteOneModel) SetFilter(filter interface{}) *DeleteOneModel

SetFilter specifies a filter to use to select the document to delete. The filter must be a document containing query operators. It cannot be nil. If the filter matches multiple documents, one will be selected from the matching documents.

func (*DeleteOneModel) SetHint added in v1.4.0 

func (dom *DeleteOneModel) SetHint(hint interface{}) *DeleteOneModel

SetHint specifies the index to use for the operation. This should either be the index name as a string or the index specification as a document. This option is only valid for MongoDB versions >= 4.4. Server versions >= 3.4 will return an error if this option is specified. For server versions < 3.4, the driver will return a client-side error if this option is specified. The driver will return an error if this option is specified during an unacknowledged write operation. The default value is nil, which means that no hint will be sent.

type DeleteResult 

type DeleteResult struct {
	DeletedCount int64 `bson:"n"` // The number of documents deleted.
}

DeleteResult is the result type returned by DeleteOne and DeleteMany operations.

type Dialer added in v0.0.3 

type Dialer interface {
	DialContext(ctx context.Context, network, address string) (net.Conn, error)
}

Dialer is used to make network connections.

type EncryptionKeyVaultError added in v1.2.0 

type EncryptionKeyVaultError struct {
	Wrapped error
}

EncryptionKeyVaultError represents an error while communicating with the key vault collection during client-side encryption.

func (EncryptionKeyVaultError) Error added in v1.2.0 

func (ekve EncryptionKeyVaultError) Error() string

Error implements the error interface.

func (EncryptionKeyVaultError) Unwrap added in v1.4.0 

func (ekve EncryptionKeyVaultError) Unwrap() error

Unwrap returns the underlying error.

type IndexModel added in v0.0.3 

type IndexModel struct {
	// A document describing which keys should be used for the index. It cannot be nil. This must be an order-preserving
	// type such as bson.D. Map types such as bson.M are not valid. See https://docs.mongodb.com/manual/indexes/#indexes
	// for examples of valid documents.
	Keys interface{}

	// The options to use to create the index.
	Options *options.IndexOptions
}

IndexModel represents a new index to be created.

type IndexOptionsBuilder deprecated added in v0.0.7 

type IndexOptionsBuilder struct {
	// contains filtered or unexported fields
}

IndexOptionsBuilder specifies options for a new index.

Deprecated: Use the IndexOptions type in the mongo/options package instead.

func NewIndexOptionsBuilder deprecated added in v0.0.7 

func NewIndexOptionsBuilder() *IndexOptionsBuilder

NewIndexOptionsBuilder creates a new IndexOptionsBuilder.

Deprecated: Use the Index function in mongo/options instead.

func (*IndexOptionsBuilder) Background deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) Background(background bool) *IndexOptionsBuilder

Background specifies a value for the background option.

Deprecated: Use the IndexOptions.SetBackground function in mongo/options instead.

func (*IndexOptionsBuilder) Bits deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) Bits(bits int32) *IndexOptionsBuilder

Bits specifies a value for the bits option.

Deprecated: Use the IndexOptions.SetBits function in mongo/options instead.

func (*IndexOptionsBuilder) BucketSize deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) BucketSize(bucketSize int32) *IndexOptionsBuilder

BucketSize specifies a value for the bucketSize option.

Deprecated: Use the IndexOptions.SetBucketSize function in mongo/options instead.

func (*IndexOptionsBuilder) Build deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) Build() bson.D

Build finishes constructing an the builder.

Deprecated: Use the IndexOptions type in the mongo/options package instead.

func (*IndexOptionsBuilder) Collation deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) Collation(collation interface{}) *IndexOptionsBuilder

Collation specifies a value for the collation option.

Deprecated: Use the IndexOptions.SetCollation function in mongo/options instead.

func (*IndexOptionsBuilder) DefaultLanguage deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) DefaultLanguage(defaultLanguage string) *IndexOptionsBuilder

DefaultLanguage specifies a value for the default_language option.

Deprecated: Use the IndexOptions.SetDefaultLanguage function in mongo/options instead.

func (*IndexOptionsBuilder) ExpireAfterSeconds deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) ExpireAfterSeconds(expireAfterSeconds int32) *IndexOptionsBuilder

ExpireAfterSeconds specifies a value for the expireAfterSeconds option.

Deprecated: Use the IndexOptions.SetExpireAfterSeconds function in mongo/options instead.

func (*IndexOptionsBuilder) LanguageOverride deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) LanguageOverride(languageOverride string) *IndexOptionsBuilder

LanguageOverride specifies a value for the language_override option.

Deprecated: Use the IndexOptions.SetLanguageOverride function in mongo/options instead.

func (*IndexOptionsBuilder) Max deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) Max(max float64) *IndexOptionsBuilder

Max specifies a value for the max option.

Deprecated: Use the IndexOptions.SetMax function in mongo/options instead.

func (*IndexOptionsBuilder) Min deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) Min(min float64) *IndexOptionsBuilder

Min specifies a value for the min option.

Deprecated: Use the IndexOptions.SetMin function in mongo/options instead.

func (*IndexOptionsBuilder) Name deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) Name(name string) *IndexOptionsBuilder

Name specifies a value for the name option.

Deprecated: Use the IndexOptions.SetName function in mongo/options instead.

func (*IndexOptionsBuilder) PartialFilterExpression deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) PartialFilterExpression(partialFilterExpression interface{}) *IndexOptionsBuilder

PartialFilterExpression specifies a value for the partialFilterExpression option.

Deprecated: Use the IndexOptions.SetPartialFilterExpression function in mongo/options instead.

func (*IndexOptionsBuilder) Sparse deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) Sparse(sparse bool) *IndexOptionsBuilder

Sparse specifies a value for the sparse option.

Deprecated: Use the IndexOptions.SetSparse function in mongo/options instead.

func (*IndexOptionsBuilder) SphereVersion deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) SphereVersion(sphereVersion int32) *IndexOptionsBuilder

SphereVersion specifies a value for the 2dsphereIndexVersion option.

Deprecated: Use the IndexOptions.SetSphereVersion function in mongo/options instead.

func (*IndexOptionsBuilder) StorageEngine deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) StorageEngine(storageEngine interface{}) *IndexOptionsBuilder

StorageEngine specifies a value for the storageEngine option.

Deprecated: Use the IndexOptions.SetStorageEngine function in mongo/options instead.

func (*IndexOptionsBuilder) TextVersion deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) TextVersion(textVersion int32) *IndexOptionsBuilder

TextVersion specifies a value for the textIndexVersion option.

Deprecated: Use the IndexOptions.SetTextVersion function in mongo/options instead.

func (*IndexOptionsBuilder) Unique deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) Unique(unique bool) *IndexOptionsBuilder

Unique specifies a value for the unique option.

Deprecated: Use the IndexOptions.SetUnique function in mongo/options instead.

func (*IndexOptionsBuilder) Version deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) Version(version int32) *IndexOptionsBuilder

Version specifies a value for the version option.

Deprecated: Use the IndexOptions.SetVersion function in mongo/options instead.

func (*IndexOptionsBuilder) Weights deprecated added in v0.0.7 

func (iob *IndexOptionsBuilder) Weights(weights interface{}) *IndexOptionsBuilder

Weights specifies a value for the weights option.

Deprecated: Use the IndexOptions.SetWeights function in mongo/options instead.

type IndexView added in v0.0.3 

type IndexView struct {
	// contains filtered or unexported fields
}

IndexView is a type that can be used to create, drop, and list indexes on a collection. An IndexView for a collection can be created by a call to Collection.Indexes().

func (IndexView) CreateMany added in v0.0.3 

func (iv IndexView) CreateMany(ctx context.Context, models []IndexModel, opts ...*options.CreateIndexesOptions) ([]string, error)

CreateMany executes a createIndexes command to create multiple indexes on the collection and returns the names of the new indexes.

For each IndexModel in the models parameter, the index name can be specified via the Options field. If a name is not given, it will be generated from the Keys document.

The opts parameter can be used to specify options for this operation (see the options.CreateIndexesOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/createIndexes/.

Example 
package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var indexView *mongo.IndexView

	// Create two indexes: {name: 1, email: 1} and {name: 1, age: 1}
	// For the first index, specify no options. The name will be generated as "name_1_email_1" by the driver.
	// For the second index, specify the Name option to explicitly set the name to "nameAge".
	models := []mongo.IndexModel{
		{
			Keys: bson.D{{"name", 1}, {"email", 1}},
		},
		{
			Keys:    bson.D{{"name", 1}, {"age", 1}},
			Options: options.Index().SetName("nameAge"),
		},
	}

	// Specify the MaxTime option to limit the amount of time the operation can run on the server
	opts := options.CreateIndexes().SetMaxTime(2 * time.Second)
	names, err := indexView.CreateMany(context.TODO(), models, opts)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("created indexes %v\n", names)
}

Output:

func (IndexView) CreateOne added in v0.0.3 

func (iv IndexView) CreateOne(ctx context.Context, model IndexModel, opts ...*options.CreateIndexesOptions) (string, error)

CreateOne executes a createIndexes command to create an index on the collection and returns the name of the new index. See the IndexView.CreateMany documentation for more information and an example.

func (IndexView) DropAll added in v0.0.3 

func (iv IndexView) DropAll(ctx context.Context, opts ...*options.DropIndexesOptions) (bson.Raw, error)

DropAll executes a dropIndexes operation to drop all indexes on the collection. If the operation succeeds, this returns a BSON document in the form {nIndexesWas: <int32>}. The "nIndexesWas" field in the response contains the number of indexes that existed prior to the drop.

The opts parameter can be used to specify options for this operation (see the options.DropIndexesOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/dropIndexes/.

func (IndexView) DropOne added in v0.0.3 

func (iv IndexView) DropOne(ctx context.Context, name string, opts ...*options.DropIndexesOptions) (bson.Raw, error)

DropOne executes a dropIndexes operation to drop an index on the collection. If the operation succeeds, this returns a BSON document in the form {nIndexesWas: <int32>}. The "nIndexesWas" field in the response contains the number of indexes that existed prior to the drop.

The name parameter should be the name of the index to drop. If the name is "*", ErrMultipleIndexDrop will be returned without running the command because doing so would drop all indexes.

The opts parameter can be used to specify options for this operation (see the options.DropIndexesOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/dropIndexes/.

func (IndexView) List added in v0.0.3 

func (iv IndexView) List(ctx context.Context, opts ...*options.ListIndexesOptions) (*Cursor, error)

List executes a listIndexes command and returns a cursor over the indexes in the collection.

The opts parameter can be used to specify options for this operation (see the options.ListIndexesOptions documentation).

For more information about the command, see https://docs.mongodb.com/manual/reference/command/listIndexes/.

Example 
package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
	var indexView *mongo.IndexView

	// Specify the MaxTime option to limit the amount of time the operation can run on the server
	opts := options.ListIndexes().SetMaxTime(2 * time.Second)
	cursor, err := indexView.List(context.TODO(), opts)
	if err != nil {
		log.Fatal(err)
	}

	// Get a slice of all indexes returned and print them out.
	var results []bson.M
	if err = cursor.All(context.TODO(), &results); err != nil {
		log.Fatal(err)
	}
	fmt.Println(results)
}

Output:

type InsertManyResult 

type InsertManyResult struct {
	// The _id values of the inserted documents. Values generated by the driver will be of type primitive.ObjectID.
	InsertedIDs []interface{}
}

InsertManyResult is a result type returned by an InsertMany operation.

type InsertOneModel added in v0.0.16 

type InsertOneModel struct {
	Document interface{}
}

InsertOneModel is used to insert a single document in a BulkWrite operation.

func NewInsertOneModel added in v0.0.16 

func NewInsertOneModel() *InsertOneModel

NewInsertOneModel creates a new InsertOneModel.

func (*InsertOneModel) SetDocument added in v0.3.0 

func (iom *InsertOneModel) SetDocument(doc interface{}) *InsertOneModel

SetDocument specifies the document to be inserted. The document cannot be nil. If it does not have an _id field when transformed into BSON, one will be added automatically to the marshalled document. The original document will not be modified.

type InsertOneResult 

type InsertOneResult struct {
	// The _id of the inserted document. A value generated by the driver will be of type primitive.ObjectID.
	InsertedID interface{}
}

InsertOneResult is the result type returned by an InsertOne operation.

type ListDatabasesResult added in v0.0.3 

type ListDatabasesResult struct {
	// A slice containing one DatabaseSpecification for each database matched by the operation's filter.
	Databases []DatabaseSpecification

	// The total size of the database files of the returned databases in bytes.
	// This will be the sum of the SizeOnDisk field for each specification in Databases.
	TotalSize int64
}

ListDatabasesResult is a result of a ListDatabases operation.

type MarshalError added in v0.0.15 

type MarshalError struct {
	Value interface{}
	Err   error
}

MarshalError is returned when attempting to transform a value into a document results in an error.

func (MarshalError) Error added in v0.0.15 

func (me MarshalError) Error() string

Error implements the error interface.

type MongocryptError added in v1.2.0 

type MongocryptError struct {
	Code    int32
	Message string
}

MongocryptError represents an libmongocrypt error during client-side encryption.

func (MongocryptError) Error added in v1.2.0 

func (m MongocryptError) Error() string

Error implements the error interface.

type MongocryptdError added in v1.2.0 

type MongocryptdError struct {
	Wrapped error
}

MongocryptdError represents an error while communicating with mongocryptd during client-side encryption.

func (MongocryptdError) Error added in v1.2.0 

func (e MongocryptdError) Error() string

Error implements the error interface.

func (MongocryptdError) Unwrap added in v1.4.0 

func (e MongocryptdError) Unwrap() error

Unwrap returns the underlying error.

type Pipeline added in v0.0.18 

type Pipeline []bson.D

Pipeline is a type that makes creating aggregation pipelines easier. It is a helper and is intended for serializing to BSON.

Example usage: 

mongo.Pipeline{
	{{"$group", bson.D{{"_id", "$state"}, {"totalPop", bson.D{{"$sum", "$pop"}}}}}},
	{{"$match", bson.D{{"totalPop", bson.D{{"$gte", 10*1000*1000}}}}}},
}

type ReplaceOneModel added in v0.0.16 

type ReplaceOneModel struct {
	Collation   *options.Collation
	Upsert      *bool
	Filter      interface{}
	Replacement interface{}
	Hint        interface{}
}

ReplaceOneModel is used to replace at most one document in a BulkWrite operation.

func NewReplaceOneModel added in v0.0.16 

func NewReplaceOneModel() *ReplaceOneModel

NewReplaceOneModel creates a new ReplaceOneModel.

func (*ReplaceOneModel) SetCollation added in v0.3.0 

func (rom *ReplaceOneModel) SetCollation(collation *options.Collation) *ReplaceOneModel

SetCollation specifies a collation to use for string comparisons. The default is nil, meaning no collation will be used.

func (*ReplaceOneModel) SetFilter added in v0.3.0 

func (rom *ReplaceOneModel) SetFilter(filter interface{}) *ReplaceOneModel

SetFilter specifies a filter to use to select the document to replace. The filter must be a document containing query operators. It cannot be nil. If the filter matches multiple documents, one will be selected from the matching documents.

func (*ReplaceOneModel) SetHint added in v1.4.0 

func (rom *ReplaceOneModel) SetHint(hint interface{}) *ReplaceOneModel

SetHint specifies the index to use for the operation. This should either be the index name as a string or the index specification as a document. This option is only valid for MongoDB versions >= 4.2. Server versions >= 3.4 will return an error if this option is specified. For server versions < 3.4, the driver will return a client-side error if this option is specified. The driver will return an error if this option is specified during an unacknowledged write operation. The default value is nil, which means that no hint will be sent.

func (*ReplaceOneModel) SetReplacement added in v0.3.0 

func (rom *ReplaceOneModel) SetReplacement(rep interface{}) *ReplaceOneModel

SetReplacement specifies a document that will be used to replace the selected document. It cannot be nil and cannot contain any update operators (https://docs.mongodb.com/manual/reference/operator/update/).

func (*ReplaceOneModel) SetUpsert added in v0.3.0 

func (rom *ReplaceOneModel) SetUpsert(upsert bool) *ReplaceOneModel

SetUpsert specifies whether or not the replacement document should be inserted if no document matching the filter is found. If an upsert is performed, the _id of the upserted document can be retrieved from the UpsertedIDs field of the BulkWriteResult.

type Session added in v0.0.10 

type Session interface {
	// Functions to modify session state.
	StartTransaction(...*options.TransactionOptions) error
	AbortTransaction(context.Context) error
	CommitTransaction(context.Context) error
	WithTransaction(ctx context.Context, fn func(sessCtx SessionContext) (interface{}, error),
		opts ...*options.TransactionOptions) (interface{}, error)
	EndSession(context.Context)

	// Functions to retrieve session properties.
	ClusterTime() bson.Raw
	OperationTime() *primitive.Timestamp
	Client() *Client
	ID() bson.Raw

	// Functions to modify mutable session properties.
	AdvanceClusterTime(bson.Raw) error
	AdvanceOperationTime(*primitive.Timestamp) error
	// contains filtered or unexported methods
}

Session is an interface that represents a MongoDB logical session. Sessions can be used to enable causal consistency for a group of operations or to execute operations in an ACID transaction. A new Session can be created from a Client instance. A Session created from a Client must only be used to execute operations using that Client or a Database or Collection created from that Client. Custom implementations of this interface should not be used in production. For more information about sessions, and their use cases, see https://docs.mongodb.com/manual/reference/server-sessions/, https://docs.mongodb.com/manual/core/read-isolation-consistency-recency/#causal-consistency, and https://docs.mongodb.com/manual/core/transactions/.

StartTransaction starts a new transaction, configured with the given options, on this session. This method will return an error if there is already a transaction in-progress for this session.

CommitTransaction commits the active transaction for this session. This method will return an error if there is no active transaction for this session or the transaction has been aborted.

AbortTransaction aborts the active transaction for this session. This method will return an error if there is no active transaction for this session or the transaction has been committed or aborted.

WithTransaction starts a transaction on this session and runs the fn callback. Errors with the TransientTransactionError and UnknownTransactionCommitResult labels are retried for up to 120 seconds. Inside the callback, sessCtx must be used as the Context parameter for any operations that should be part of the transaction. If the ctx parameter already has a Session attached to it, it will be replaced by this session. The fn callback may be run multiple times during WithTransaction due to retry attempts, so it must be idempotent. Non-retryable operation errors or any operation errors that occur after the timeout expires will be returned without retrying. For a usage example, see the Client.StartSession method documentation.

ClusterTime, OperationTime, Client, and ID return the session's current operation time, the session's current cluster time, the Client associated with the session, and the ID document associated with the session, respectively. The ID document for a session is in the form {"id": <BSON binary value>}.

EndSession method should abort any existing transactions and close the session.

AdvanceClusterTime and AdvanceOperationTime are for internal use only and must not be called.

func SessionFromContext added in v1.4.0 

func SessionFromContext(ctx context.Context) Session

SessionFromContext extracts the mongo.Session object stored in a Context. This can be used on a SessionContext that was created implicitly through one of the callback-based session APIs or explicitly by calling NewSessionContext. If there is no Session stored in the provided Context, nil is returned.

type SessionContext added in v0.0.16 

type SessionContext interface {
	context.Context
	Session
}

SessionContext combines the context.Context and mongo.Session interfaces. It should be used as the Context arguments to operations that should be executed in a session. This type is not goroutine safe and must not be used concurrently by multiple goroutines.

There are two ways to create a SessionContext and use it in a session/transaction. The first is to use one of the callback-based functions such as WithSession and UseSession. These functions create a SessionContext and pass it to the provided callback. The other is to use NewSessionContext to explicitly create a SessionContext.

func NewSessionContext added in v1.4.0 

func NewSessionContext(ctx context.Context, sess Session) SessionContext

NewSessionContext creates a new SessionContext associated with the given Context and Session parameters.

Example 
package main

import (
	"context"
	"fmt"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
)

func main() {
	var client *mongo.Client

	// Create a new Session and SessionContext.
	sess, err := client.StartSession()
	if err != nil {
		panic(err)
	}
	defer sess.EndSession(context.TODO())
	sessCtx := mongo.NewSessionContext(context.TODO(), sess)

	// Start a transaction and sessCtx as the Context parameter to InsertOne and FindOne so both operations will be
	// run in the transaction.
	if err = sess.StartTransaction(); err != nil {
		panic(err)
	}

	coll := client.Database("db").Collection("coll")
	res, err := coll.InsertOne(sessCtx, bson.D{{"x", 1}})
	if err != nil {
		// Abort the transaction after an error. Use context.Background() to ensure that the abort can complete
		// successfully even if the context passed to NewSessionContext is changed to have a timeout.
		_ = sess.AbortTransaction(context.Background())
		panic(err)
	}

	var result bson.M
	if err = coll.FindOne(sessCtx, bson.D{{"_id", res.InsertedID}}).Decode(&result); err != nil {
		// Abort the transaction after an error. Use context.Background() to ensure that the abort can complete
		// successfully even if the context passed to NewSessionContext is changed to have a timeout.
		_ = sess.AbortTransaction(context.Background())
		panic(err)
	}
	fmt.Printf("result: %v\n", result)

	// Commit the transaction so the inserted document will be stored. Use context.Background() to ensure that the
	// commit can complete successfully even if the context passed to NewSessionContext is changed to have a timeout.
	if err = sess.CommitTransaction(context.Background()); err != nil {
		panic(err)
	}
}

Output:

type SingleResult added in v0.1.0 

type SingleResult struct {
	// contains filtered or unexported fields
}

SingleResult represents a single document returned from an operation. If the operation resulted in an error, all SingleResult methods will return that error. If the operation did not return any documents, all SingleResult methods will return ErrNoDocuments.

func (*SingleResult) Decode added in v0.1.0 

func (sr *SingleResult) Decode(v interface{}) error

Decode will unmarshal the document represented by this SingleResult into v. If there was an error from the operation that created this SingleResult, that error will be returned. If the operation returned no documents, Decode will return ErrNoDocuments.

If the operation was successful and returned a document, Decode will return any errors from the unmarshalling process without any modification. If v is nil or is a typed nil, an error will be returned.

func (*SingleResult) DecodeBytes added in v0.1.0 

func (sr *SingleResult) DecodeBytes() (bson.Raw, error)

DecodeBytes will return the document represented by this SingleResult as a bson.Raw. If there was an error from the operation that created this SingleResult, both the result and that error will be returned. If the operation returned no documents, this will return (nil, ErrNoDocuments).

func (*SingleResult) Err added in v0.1.0 

func (sr *SingleResult) Err() error

Err returns the error from the operation that created this SingleResult. If the operation was successful but did not return any documents, Err will return ErrNoDocuments. If the operation was successful and returned a document, Err will return nil.

type StreamType added in v0.1.0 

type StreamType uint8

StreamType represents the cluster type against which a ChangeStream was created. 

const (
	CollectionStream StreamType = iota
	DatabaseStream
	ClientStream
)

These constants represent valid change stream types. A change stream can be initialized over a collection, all collections in a database, or over a cluster.

type UpdateManyModel added in v0.0.16 

type UpdateManyModel struct {
	Collation    *options.Collation
	Upsert       *bool
	Filter       interface{}
	Update       interface{}
	ArrayFilters *options.ArrayFilters
	Hint         interface{}
}

UpdateManyModel is used to update multiple documents in a BulkWrite operation.

func NewUpdateManyModel added in v0.0.16 

func NewUpdateManyModel() *UpdateManyModel

NewUpdateManyModel creates a new UpdateManyModel.

func (*UpdateManyModel) SetArrayFilters added in v0.3.0 

func (umm *UpdateManyModel) SetArrayFilters(filters options.ArrayFilters) *UpdateManyModel

SetArrayFilters specifies a set of filters to determine which elements should be modified when updating an array field.

func (*UpdateManyModel) SetCollation added in v0.3.0 

func (umm *UpdateManyModel) SetCollation(collation *options.Collation) *UpdateManyModel

SetCollation specifies a collation to use for string comparisons. The default is nil, meaning no collation will be used.

func (*UpdateManyModel) SetFilter added in v0.3.0 

func (umm *UpdateManyModel) SetFilter(filter interface{}) *UpdateManyModel

SetFilter specifies a filter to use to select documents to update. The filter must be a document containing query operators. It cannot be nil.

func (*UpdateManyModel) SetHint added in v1.4.0 

func (umm *UpdateManyModel) SetHint(hint interface{}) *UpdateManyModel

SetHint specifies the index to use for the operation. This should either be the index name as a string or the index specification as a document. This option is only valid for MongoDB versions >= 4.2. Server versions >= 3.4 will return an error if this option is specified. For server versions < 3.4, the driver will return a client-side error if this option is specified. The driver will return an error if this option is specified during an unacknowledged write operation. The default value is nil, which means that no hint will be sent.

func (*UpdateManyModel) SetUpdate added in v0.3.0 

func (umm *UpdateManyModel) SetUpdate(update interface{}) *UpdateManyModel

SetUpdate specifies the modifications to be made to the selected documents. The value must be a document containing update operators (https://docs.mongodb.com/manual/reference/operator/update/). It cannot be nil or empty.

func (*UpdateManyModel) SetUpsert added in v0.3.0 

func (umm *UpdateManyModel) SetUpsert(upsert bool) *UpdateManyModel

SetUpsert specifies whether or not a new document should be inserted if no document matching the filter is found. If an upsert is performed, the _id of the upserted document can be retrieved from the UpsertedIDs field of the BulkWriteResult.

type UpdateOneModel added in v0.0.16 

type UpdateOneModel struct {
	Collation    *options.Collation
	Upsert       *bool
	Filter       interface{}
	Update       interface{}
	ArrayFilters *options.ArrayFilters
	Hint         interface{}
}

UpdateOneModel is used to update at most one document in a BulkWrite operation.

func NewUpdateOneModel added in v0.0.16 

func NewUpdateOneModel() *UpdateOneModel

NewUpdateOneModel creates a new UpdateOneModel.

func (*UpdateOneModel) SetArrayFilters added in v0.3.0 

func (uom *UpdateOneModel) SetArrayFilters(filters options.ArrayFilters) *UpdateOneModel

SetArrayFilters specifies a set of filters to determine which elements should be modified when updating an array field.

func (*UpdateOneModel) SetCollation added in v0.3.0 

func (uom *UpdateOneModel) SetCollation(collation *options.Collation) *UpdateOneModel

SetCollation specifies a collation to use for string comparisons. The default is nil, meaning no collation will be used.

func (*UpdateOneModel) SetFilter added in v0.3.0 

func (uom *UpdateOneModel) SetFilter(filter interface{}) *UpdateOneModel

SetFilter specifies a filter to use to select the document to update. The filter must be a document containing query operators. It cannot be nil. If the filter matches multiple documents, one will be selected from the matching documents.

func (*UpdateOneModel) SetHint added in v1.4.0 

func (uom *UpdateOneModel) SetHint(hint interface{}) *UpdateOneModel

SetHint specifies the index to use for the operation. This should either be the index name as a string or the index specification as a document. This option is only valid for MongoDB versions >= 4.2. Server versions >= 3.4 will return an error if this option is specified. For server versions < 3.4, the driver will return a client-side error if this option is specified. The driver will return an error if this option is specified during an unacknowledged write operation. The default value is nil, which means that no hint will be sent.

func (*UpdateOneModel) SetUpdate added in v0.3.0 

func (uom *UpdateOneModel) SetUpdate(update interface{}) *UpdateOneModel

SetUpdate specifies the modifications to be made to the selected document. The value must be a document containing update operators (https://docs.mongodb.com/manual/reference/operator/update/). It cannot be nil or empty.

func (*UpdateOneModel) SetUpsert added in v0.3.0 

func (uom *UpdateOneModel) SetUpsert(upsert bool) *UpdateOneModel

SetUpsert specifies whether or not a new document should be inserted if no document matching the filter is found. If an upsert is performed, the _id of the upserted document can be retrieved from the UpsertedIDs field of the BulkWriteResult.

type UpdateResult 

type UpdateResult struct {
	MatchedCount  int64       // The number of documents matched by the filter.
	ModifiedCount int64       // The number of documents modified by the operation.
	UpsertedCount int64       // The number of documents upserted by the operation.
	UpsertedID    interface{} // The _id field of the upserted document, or nil if no upsert was done.
}

UpdateResult is the result type returned from UpdateOne, UpdateMany, and ReplaceOne operations.

func (*UpdateResult) UnmarshalBSON 

func (result *UpdateResult) UnmarshalBSON(b []byte) error

UnmarshalBSON implements the bson.Unmarshaler interface.

type WriteConcernError added in v0.0.4 

type WriteConcernError struct {
	Name    string
	Code    int
	Message string
	Details bson.Raw
}

WriteConcernError represents a write concern failure during execution of a write operation. This error type is only returned as part of a WriteException or a BulkWriteException.

func (WriteConcernError) Error added in v0.0.4 

func (wce WriteConcernError) Error() string

Error implements the error interface.

type WriteError added in v0.0.4 

type WriteError struct {
	// The index of the write in the slice passed to an InsertMany or BulkWrite operation that caused this error.
	Index int

	Code    int
	Message string
}

WriteError is an error that occurred during execution of a write operation. This error type is only returned as part of a WriteException or BulkWriteException.

func (WriteError) Error added in v0.0.4 

func (we WriteError) Error() string

type WriteErrors added in v0.0.4 

type WriteErrors []WriteError

WriteErrors is a group of write errors that occurred during execution of a write operation.

func (WriteErrors) Error added in v0.0.4 

func (we WriteErrors) Error() string

Error implements the error interface.

type WriteException added in v0.3.0 

type WriteException struct {
	// The write concern error that occurred, or nil if there was none.
	WriteConcernError *WriteConcernError

	// The write errors that occurred during operation execution.
	WriteErrors WriteErrors

	// The categories to which the exception belongs.
	Labels []string
}

WriteException is the error type returned by the InsertOne, DeleteOne, DeleteMany, UpdateOne, UpdateMany, and ReplaceOne operations.

func (WriteException) Error added in v0.3.0 

func (mwe WriteException) Error() string

Error implements the error interface.

func (WriteException) HasErrorLabel added in v1.4.0 

func (mwe WriteException) HasErrorLabel(label string) bool

HasErrorLabel returns true if the error contains the specified label.

type WriteModel added in v0.0.16 

type WriteModel interface {
	// contains filtered or unexported methods
}

WriteModel is an interface implemented by models that can be used in a BulkWrite operation. Each WriteModel represents a write.

This interface is implemented by InsertOneModel, DeleteOneModel, DeleteManyModel, ReplaceOneModel, UpdateOneModel, and UpdateManyModel. Custom implementations of this interface must not be used.

type XSession deprecated added in v1.2.0 

type XSession interface {
	ClientSession() *session.Client
}

XSession is an unstable interface for internal use only.

Deprecated: This interface is unstable because it provides access to a session.Client object, which exists in the "x" package. It should not be used by applications and may be changed or removed in any release.

Source Files

View all Source files

Directories

Path Synopsis
Package gridfs provides a MongoDB GridFS API.
 Package gridfs provides a MongoDB GridFS API.
mtest

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