mongo-driver

README

MongoDB Go Driver

The MongoDB supported driver for Go.

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Requirements

• Go 1.18 or higher. We aim to support the latest versions of Go.
• Go 1.20 or higher is required to run the driver test suite.
• MongoDB 3.6 and higher.

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Installation

The recommended way to get started using the MongoDB Go driver is by using Go modules to install the dependency in your project. This can be done either by importing packages from go.mongodb.org/mongo-driver and having the build step install the dependency or by explicitly running

go get go.mongodb.org/mongo-driver/mongo

When using a version of Go that does not support modules, the driver can be installed using dep by running

dep ensure -add "go.mongodb.org/mongo-driver/mongo"

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Usage

To get started with the driver, import the mongo package and create a mongo.Client with the Connect function:

import (
    "context"
    "time"

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

ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()
client, err := mongo.Connect(options.Client().ApplyURI("mongodb://localhost:27017"))

Make sure to defer a call to Disconnect after instantiating your client:

defer func() {
    if err = client.Disconnect(ctx); err != nil {
        panic(err)
    }
}()

For more advanced configuration and authentication, see the documentation for mongo.Connect.

Calling Connect does not block for server discovery. If you wish to know if a MongoDB server has been found and connected to, use the Ping method:

ctx, cancel = context.WithTimeout(context.Background(), 2*time.Second)
defer cancel()
err = client.Ping(ctx, readpref.Primary())

To insert a document into a collection, first retrieve a Database and then Collection instance from the Client:

collection := client.Database("testing").Collection("numbers")

The Collection instance can then be used to insert documents:

ctx, cancel = context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
res, err := collection.InsertOne(ctx, bson.D{{"name", "pi"}, {"value", 3.14159}})
id := res.InsertedID

To use bson.D, you will need to add "go.mongodb.org/mongo-driver/bson" to your imports.

Your import statement should now look like this:

import (
    "context"
    "log"
    "time"

    "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"
)

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

ctx, cancel = context.WithTimeout(context.Background(), 30*time.Second)
defer cancel()
cur, err := collection.Find(ctx, bson.D{})
if err != nil { log.Fatal(err) }
defer cur.Close(ctx)
for cur.Next(ctx) {
    var result bson.D
    err := cur.Decode(&result)
    if err != nil { log.Fatal(err) }
    // do something with result....
}
if err := cur.Err(); err != nil {
    log.Fatal(err)
}

For methods that return a single item, a SingleResult instance is returned:

var result struct {
    Value float64
}
filter := bson.D{{"name", "pi"}}
ctx, cancel = context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
err = collection.FindOne(ctx, filter).Decode(&result)
if err == mongo.ErrNoDocuments {
    // Do something when no record was found
    fmt.Println("record does not exist")
} else if err != nil {
    log.Fatal(err)
}
// Do something with result...

Additional examples and documentation can be found under the examples directory and on the MongoDB Documentation website.

Network Compression

Network compression will reduce bandwidth requirements between MongoDB and the application.

The Go Driver supports the following compression algorithms:

1. Snappy (snappy): available in MongoDB 3.4 and later.
2. Zlib (zlib): available in MongoDB 3.6 and later.
3. Zstandard (zstd): available in MongoDB 4.2 and later.

Specify Compression Algorithms

Compression can be enabled using the compressors parameter on the connection string or by using ClientOptions.SetCompressors:

opts := options.Client().ApplyURI("mongodb://localhost:27017/?compressors=snappy,zlib,zstd")
client, _ := mongo.Connect(opts)

opts := options.Client().SetCompressors([]string{"snappy", "zlib", "zstd"})
client, _ := mongo.Connect(opts)

If compressors are set, the Go Driver negotiates with the server to select the first common compressor. For server configuration and defaults, refer to networkMessageCompressors.

Messages compress when both parties enable network compression; otherwise, messages remain uncompressed

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Feedback

For help with the driver, please post in the MongoDB Community Forums.

New features and bugs can be reported on jira: https://jira.mongodb.org/browse/GODRIVER

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Contribution

Check out the project page for tickets that need completing. See our contribution guidelines for details.

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Continuous Integration

Commits to master are run automatically on evergreen.

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Frequently Encountered Issues

See our common issues documentation for troubleshooting frequently encountered issues.

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Thanks and Acknowledgement

• The Go Gopher artwork by @ashleymcnamara
• The original Go Gopher was designed by Renee French

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License

The MongoDB Go Driver is licensed under the Apache License.