dynago

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README

Dynago

Dynago is a DynamoDB client API for Go.

This attempts to be a really simple, principle of least-surprise client for the DynamoDB API.

Key design tenets of Dynago:

  • Most actions are done via chaining to build filters and conditions
  • all objects are completely safe for passing between goroutines (even queries and the like)
  • To make understanding easier via docs, we use amazon's naming wherever possible.

Installation

Install using go get:

go get gopkg.in/underarmour/dynago.v1

Docs are at http://godoc.org/gopkg.in/underarmour/dynago.v1

Example

Run a query:

client := dynago.NewClient(endpoint, accessKey, secretKey)

query := client.Query(table).
	KeyConditionExpression("UserId = :uid", dynago.Param{":uid", 42}).
	FilterExpression("NumViews > :views").
	Param(":views", 50).
	Desc()

result, err := query.Execute()
if err != nil {
	// do something
}
for _, row := range result.Items {
	fmt.Printf("Name: %s, Views: %d", row["Name"], row["NumViews"])
}

Type Marshaling

Dynago attempts to let you use go types instead of having to understand a whole lot about dynamo's internal type system.

Example:

doc := dynago.Document{
	"name": "Bob",
	"age": 45,
	"height": 2.1,
	"address": dynago.Document{
		"city": "Boston",
	},
	"tags": dynago.StringSet{"male", "middle_aged"},
}
client.PutItem("person", doc).Execute()
  • Strings use golang string
  • Numbers can be input as int or float64 but always are returned as dynago.Number to not lose precision.
  • Maps can be either map[string]interface{} or dynago.Document
  • Opaque binary data can be put in []byte
  • String sets, number sets, binary sets are supported using dynago.StringSet dynago.NumberSet dynago.BinarySet
  • Lists are supported using dynago.List
  • time.Time is only accepted if it's a UTC time, and is marshaled to a dynamo string in iso8601 compact format. It comes back as a string, an can be got back using GetTime() on Document.

Documentation

Overview

Dynago is a DynamoDB client API for Go.

Dynago differs from other Dynamo clients for Go in that it tries to mirror DynamoDB's core API closely: Most methods, attributes, and names are made following Dynamo's own naming conventions. This allows it to be clear which API is being accessed and allows finding complementary docs on Amazon's side easier.

Filter Chaining

A key design concept is the use of chaining to build filters and conditions, similar to some ORM frameworks. This allows using sub-features like conditional puts, expression post-filtering, and so on to be clearer, because this means a conditional put is simply a PutItem with a condition expression tacked on. 

query := client.Query("Table").
	KeyConditionExpression("Foo = :foo", dynago.Param{":foo", 42}).
	Limit(40).Desc()
result, err := query.Execute()

All the various item-based query actions are evaluated when you call the Execute() method on a filter chain.

Type Marshaling

Dynago tries to marshal to/from Go types where possible:

  • Strings use golang string
  • Numbers can be input as int, int64, float64, etc but always are returned as dynago.Number to not lose precision.
  • Maps can be either map[string]interface{} or dynago.Document
  • Opaque binary data can be put in []byte
  • String sets, number sets, binary sets are supported using dynago.StringSet, dynago.NumberSet, dynago.BinarySet
  • Lists are supported using dynago.List
  • time.Time is only accepted if it's a UTC time, and is marshaled to a dynamo string in iso8601 compact format. It comes back as a string, an can be unmarshaled back using GetTime on document.

Query Parameters

Nearly all the operations on items allow using DynamoDB's expression language to do things like query filtering, attribute projection, and so on. In order to provide literal values, queries are parametric, just like many SQL engines: 

SET Foo = Foo + :incr
DELETE Person.#n

DynamoDB has two fields it uses for parameters: ExpressionAttributeNames for name aliases, and ExpressionAttributeValues for parametric values. For simplicity, in the Dynago library both of those are serviced by Param. This is okay because parameters and aliases are non-ambiguous in that the former are named e.g. ":foo" and the latter "#foo".

So a conditional PutItem might look like: 

client.PutItem(table, item).
	ConditionExpression("Foo.#n = :fooName").
	Param("#n", "Name").Param(":fooName", "Bob").
	Execute()

In this case, we only execute the query if the value at document path Foo.Name was the string value "Bob". Note we used the "Param" helper for setting both values.

There are also helpers that let you set multiple parameters, or inline with expressions: 

query.FilterExpression("#foo > :foo", Param{":foo", 45}, Param{"#foo", "Foo"})
-or-
query.Params(Param{":foo", 45}, Param{"#foo", "Foo"})
-or-
query.Params(Document{":foo":45, "#foo": "Foo"})
Example 
package main

import (
	"fmt"
	"gopkg.in/underarmour/dynago.v1"
)

var region, accessKey, secretKey, table string

func main() {
	client := dynago.NewAwsClient(region, accessKey, secretKey)

	query := client.Query(table).
		FilterExpression("NumViews > :views").
		Param(":views", 50).
		Desc()

	result, err := query.Execute()
	if err != nil {
		// do something
	}
	for _, row := range result.Items {
		fmt.Printf("Name: %s, Views: %d", row["Name"], row["NumViews"])
	}
}

func main(client *dynago.Client) {
	type MyStruct struct {
		Id          int64
		Name        string
		Description string
		Tags        []string
		Address     struct {
			City  string
			State string
		}
	}

	var data MyStruct

	doc := dynago.Document{
		// Basic fields like numbers and strings get marshaled automatically
		"Id":          data.Id,
		"Name":        data.Name,
		"Description": data.Description,
		// StringSet is compatible with []string so we can simply cast it
		"Tags": dynago.StringSet(data.Tags),
		// We don't automatically marshal structs, nest it in a document
		"Address": dynago.Document{
			"City":  data.Address.City,
			"State": data.Address.State,
		},
	}

	client.PutItem("Table", doc).Execute()
}

Output:

Index

Examples

Constants

View Source 
const (
	ErrorUnknown codes.ErrorCode = iota

	ErrorConditionFailed        // Conditional put/update failed; condition not met
	ErrorCollectionSizeExceeded // Item collection (local secondary index) too large
	ErrorThroughputExceeded     // Exceeded provisioned throughput for table or shard
	ErrorNotFound               // Resource referenced by key not found
	ErrorInternalFailure        // Internal server error
	ErrorAuth                   // Encapsulates various authorization errors
	ErrorInvalidParameter       // Encapsulates many forms of invalid input errors
	ErrorServiceUnavailable     // Amazon service unavailable
	ErrorThrottling             // Amazon is throttling us, try later
	ErrorResourceInUse          // Tried to create existing table, delete a table in CREATING state, etc.

	// DynamoDB Streams-specific errors
	ErrorExpiredIterator // Iterator is no longer valid
	ErrorTrimmedData     // Attempted to access data older than 24h
)

Variables

View Source 
var DebugFunc func(format string, v ...interface{})

Set the target of debug. Must be set for debug to be used.

Functions

This section is empty.

Types

type AwsExecutor 

type AwsExecutor struct {
	// Underlying implementation that makes requests for this executor. It
	// is called to make every request that the executor makes. Swapping the
	// underlying implementation is not thread-safe and therefore not
	// recommended in production code.
	Requester AwsRequester
}

The AwsExecutor is the actual underlying implementation that turns dynago request structs and makes actual queries.

func NewAwsExecutor 

func NewAwsExecutor(endpoint, region, accessKey, secretKey string) *AwsExecutor

Create an AWS executor with a specified endpoint and AWS parameters.

func (*AwsExecutor) BatchWriteItem 

func (e *AwsExecutor) BatchWriteItem(b *BatchWrite) (result *BatchWriteResult, err error)

func (*AwsExecutor) DeleteItem 

func (e *AwsExecutor) DeleteItem(d *DeleteItem) (res *DeleteItemResult, err error)

func (*AwsExecutor) GetItem 

func (e *AwsExecutor) GetItem(g *GetItem) (result *GetItemResult, err error)

func (*AwsExecutor) MakeRequestUnmarshal 

func (e *AwsExecutor) MakeRequestUnmarshal(method string, document interface{}, dest interface{}) (err error)

Make a request to the underlying requester, marshaling document as JSON, and if the requester doesn't error, unmarshaling the response back into dest.

This method is mostly exposed for those implementing custom executors or prototyping new functionality.

func (*AwsExecutor) PutItem 

func (e *AwsExecutor) PutItem(p *PutItem) (res *PutItemResult, err error)

func (*AwsExecutor) Query 

func (e *AwsExecutor) Query(q *Query) (result *QueryResult, err error)

func (*AwsExecutor) Scan 

func (e *AwsExecutor) Scan(s *Scan) (result *ScanResult, err error)

func (*AwsExecutor) SchemaExecutor 

func (e *AwsExecutor) SchemaExecutor() SchemaExecutor

func (*AwsExecutor) UpdateItem 

func (e *AwsExecutor) UpdateItem(u *UpdateItem) (result *UpdateItemResult, err error)

type AwsRequester 

type AwsRequester interface {
	MakeRequest(target string, body []byte) ([]byte, error)
}

type BatchWrite 

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

func (BatchWrite) Delete 

func (b BatchWrite) Delete(table string, keys ...Document) *BatchWrite

Add some number of deletes for a table.

func (*BatchWrite) Execute 

func (b *BatchWrite) Execute() (*BatchWriteResult, error)

func (BatchWrite) Put 

func (b BatchWrite) Put(table string, items ...Document) *BatchWrite

Add some number of puts for a table.

type BatchWriteResult 

type BatchWriteResult struct {
	UnprocessedItems BatchWriteTableMap
}

type BatchWriteTableEntry 

type BatchWriteTableEntry struct {
	DeleteRequest *batchDelete `json:",omitempty"`
	PutRequest    *batchPut    `json:",omitempty"`
}

func (*BatchWriteTableEntry) SetDelete 

func (e *BatchWriteTableEntry) SetDelete(key Document)

Set this table entry as a delete request

func (*BatchWriteTableEntry) SetPut 

func (e *BatchWriteTableEntry) SetPut(item Document)

type BatchWriteTableMap 

type BatchWriteTableMap map[string][]*BatchWriteTableEntry

func (BatchWriteTableMap) GetDeleteKeys 

func (m BatchWriteTableMap) GetDeleteKeys(table string) (deletes []Document)

Convenience method to get delete keys in this batch write map for a specific table

func (BatchWriteTableMap) GetPuts 

func (m BatchWriteTableMap) GetPuts(table string) (puts []Document)

Convenience method to get all put documents in this batch write map for a specific table

type BinarySet 

type BinarySet [][]byte

type CapacityDetail 

type CapacityDetail string
const (
	CapacityIndexes CapacityDetail = "INDEXES"
	CapacityTotal   CapacityDetail = "TOTAL"
	CapacityNone    CapacityDetail = "NONE"
)

type Client 

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

func NewAwsClient 

func NewAwsClient(region string, accessKey string, secretKey string) *Client

Create a new dynamo client set up for AWS executor.

region is the AWS region, e.g. us-east-1. accessKey is your amazon access key ID. secretKey is your amazon secret key ID.

func NewClient 

func NewClient(executor Executor) *Client

Create a new client.

For most use cases other than testing and mocking, you should be able to use NewAwsClient which is a shortcut for this

func (*Client) BatchWrite 

func (c *Client) BatchWrite() *BatchWrite

Compose a batch write.

Batch writes can compose a number of put or delete, even across multiple tables, in a single operation.

func (*Client) CreateTable 

func (c *Client) CreateTable(req *schema.CreateRequest) (*schema.CreateResult, error)

Create a table.

func (*Client) DeleteItem 

func (c *Client) DeleteItem(table string, key Document) *DeleteItem

Compose a DeleteItem on a dynamo key

func (*Client) DeleteTable 

func (c *Client) DeleteTable(table string) (*schema.DeleteResult, error)

Delete a table.

func (*Client) DescribeTable 

func (c *Client) DescribeTable(table string) (*schema.DescribeResponse, error)

func (*Client) GetItem 

func (c *Client) GetItem(table string, key Document) *GetItem

Compose a GetItem on a dynamo table.

key should be a Document containing enough attributes to describe the primary key.

You can use the HashKey or HashRangeKey helpers to help build a key: 

client.GetItem("foo", dynago.HashKey("Id", 45))

client.GetItem("foo", dynago.HashRangeKey("UserId", 45, "Date", "20140512"))

func (*Client) ListTables 

func (c *Client) ListTables() *ListTables

func (*Client) PutItem 

func (c *Client) PutItem(table string, item Document) *PutItem

Compose a PutItem on a dynamo table.

item should be a document representing the record and containing the attributes for the primary key.

Like all the other requests, you must call `Execute()` to run this.

func (*Client) Query 

func (c *Client) Query(table string) *Query

Compose a Query on a dynamo table.

This returns a new Query struct which you can compose via chaining to build the query you want. Then finish the chain by calling Execute() to run the query.

func (*Client) Scan 

func (c *Client) Scan(table string) *Scan

Compose a Scan on a dynamo table.

func (*Client) UpdateItem 

func (c *Client) UpdateItem(table string, key Document) *UpdateItem

Compose an UpdateItem on a dynamo table.

type DebugFlags 

type DebugFlags uint
const (
	DebugRequests DebugFlags = 1 << iota
	DebugResponses
	DebugAuth
)
var Debug DebugFlags

Set the debug mode.

This is a set of bit-flags you can use to set up how much debugging dynago uses: 

dynago.Debug = dynago.DebugRequests | dynago.DebugResponses

func (DebugFlags) HasFlag 

func (v DebugFlags) HasFlag(flag DebugFlags) bool

Convenience method to check if a value has a flag: 

Debug.HasFlags(DebugRequests)

type DeleteItem 

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

func (DeleteItem) ConditionExpression 

func (d DeleteItem) ConditionExpression(expression string, params ...Params) *DeleteItem

Set a ConditionExpression to do a conditional DeleteItem.

func (*DeleteItem) Execute 

func (d *DeleteItem) Execute() (res *DeleteItemResult, err error)

Actually Execute this putitem.

DeleteItemResult will be nil unless ReturnValues is set.

func (DeleteItem) ReturnValues 

func (d DeleteItem) ReturnValues(returnValues ReturnValues) *DeleteItem

Set ReturnValues. For DeleteItem, it can only be ReturnAllOld

type DeleteItemResult 

type DeleteItemResult struct {
	Attributes Document
}

type Document 

type Document map[string]interface{}

Represents an entire document structure composed of keys and dynamo value

func HashKey 

func HashKey(name string, value interface{}) Document

Helper to build a hash key.

func HashRangeKey 

func HashRangeKey(hashName string, hashVal interface{}, rangeName string, rangeVal interface{}) Document

Helper to build a hash-range key.

func (Document) AsParams 

func (d Document) AsParams() (params []Param)

Allow a document to be used to specify params

func (Document) GetBool 

func (d Document) GetBool(key string) bool

Gets the value at the key as a boolean.

If the value does not exist in this Document, returns false. If the value is the nil interface, also returns false. If the value is a bool, returns the value of the bool. If the value is a Number, returns true if value is non-zero. For any other values, panics

func (Document) GetList 

func (d Document) GetList(key string) List

Helper to get a key from document as a List.

If value at key is nil, returns a nil list. If value at key is not a List, will panic.

func (Document) GetNumber 

func (d Document) GetNumber(key string) Number

func (Document) GetString 

func (d Document) GetString(key string) string

Helper to get a string from a document.

func (Document) GetStringSet 

func (d Document) GetStringSet(key string) StringSet

func (Document) GetTime 

func (d Document) GetTime(key string) (t *time.Time)

Helper to get a Time from a document.

If the value is omitted from the DB, or an empty string, then the return is nil. If the value fails to parse as iso8601, then this method panics.

func (Document) MarshalJSON 

func (d Document) MarshalJSON() ([]byte, error)

func (*Document) UnmarshalJSON 

func (d *Document) UnmarshalJSON(buf []byte) error

type Error 

type Error struct {
	Type          codes.ErrorCode // Parsed and mapped down type
	AmazonRawType string          // Raw error type from amazon
	Exception     string          // Exception from amazon
	Message       string          // Raw message from amazon
	Request       *http.Request   // If available, HTTP request
	RequestBody   []byte          // If available, raw request body bytes
	Response      *http.Response  // If available, HTTP response
	ResponseBody  []byte          // If available, raw response body bytes
}

Encapsulates errors coming from amazon/dynamodb

func (*Error) Error 

func (e *Error) Error() string

type Executor 

type Executor interface {
	BatchWriteItem(*BatchWrite) (*BatchWriteResult, error)
	DeleteItem(*DeleteItem) (*DeleteItemResult, error)
	GetItem(*GetItem) (*GetItemResult, error)
	PutItem(*PutItem) (*PutItemResult, error)
	Query(*Query) (*QueryResult, error)
	Scan(*Scan) (*ScanResult, error)
	UpdateItem(*UpdateItem) (*UpdateItemResult, error)
	SchemaExecutor() SchemaExecutor
}

This interface defines how all the various queries manage their internal execution logic.

Executor is primarily provided so that testing and mocking can be done on the API level, not just the transport level.

Executor can also optionally return a SchemaExecutor to execute schema actions.

type GetItem 

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

func (GetItem) ConsistentRead 

func (p GetItem) ConsistentRead(strong bool) *GetItem

Set up this get to be a strongly consistent read.

func (*GetItem) Execute 

func (p *GetItem) Execute() (result *GetItemResult, err error)

Execute the get item.

func (GetItem) Param 

func (p GetItem) Param(key string, value interface{}) *GetItem

Shortcut to set an ExpressionAttributeValue for used in expression query

func (GetItem) Params 

func (p GetItem) Params(params ...Params) *GetItem

func (GetItem) ProjectionExpression 

func (p GetItem) ProjectionExpression(expression string) *GetItem

Set the ProjectionExpression for this GetItem (which attributes to get)

type GetItemResult 

type GetItemResult struct {
	Item             Document
	ConsumedCapacity interface{} // TODO
}

The result from executing a GetItem.

type List 

type List []interface{}

func (List) AsDocumentList 

func (l List) AsDocumentList() ([]Document, error)

Return a copy of this list with all elements coerced as Documents.

It's very common to use lists in dynago where all elements in the list are a Document. For that reason, this method is provided as a convenience to get back your list as a list of documents.

If any element in the List is not a document, this will error. As a convenience, even when it errors, a slice containing any elements preceding the one which errored as documents will be given.

type ListTables 

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

func (*ListTables) Execute 

func (l *ListTables) Execute() (result *ListTablesResult, err error)

func (ListTables) Limit 

func (l ListTables) Limit(limit uint) *ListTables

type ListTablesResult 

type ListTablesResult struct {
	TableNames []string
	// contains filtered or unexported fields
}

func (ListTablesResult) Next 

func (r ListTablesResult) Next() *ListTables

Helper to get the ListTables for the next page of listings. If there is not a next page, returns nil

type MockExecutor 

type MockExecutor struct {
	Calls []MockExecutorCall // All calls made through this executor

	DeleteItemCalled bool
	DeleteItemCall   *MockExecutorCall
	DeleteItemResult *DeleteItemResult
	DeleteItemError  error

	PutItemCalled bool
	PutItemCall   *MockExecutorCall
	PutItemResult *PutItemResult
	PutItemError  error

	GetItemCalled bool
	GetItemCall   *MockExecutorCall
	GetItemResult *GetItemResult
	GetItemError  error

	BatchWriteItemCalled bool
	BatchWriteItemCall   *MockExecutorCall
	BatchWriteItemError  error

	QueryCalled bool              // True if query was called at least once
	QueryCall   *MockExecutorCall // Info for the last call to Query
	QueryError  error             // Specify the error from Query
	QueryResult *QueryResult      // Specify the result from Query

	ScanCalled bool
	ScanCall   *MockExecutorCall
	ScanResult *ScanResult
	ScanError  error

	UpdateItemCalled bool
	UpdateItemCall   *MockExecutorCall
	UpdateItemResult *UpdateItemResult
	UpdateItemError  error
}

A Mock executor for purpose of testing.

This Executor doesn't actually run any network requests, so it can be used in unit testing for your own application which uses Dynago. It can be asserted on whether a specific underlying method got called, what it was called with, and the nature of how the query was built. You can also for most methods control which result is returned in order to control how results make it back to the application. 

// example, normally you'd call into a real application not inside your
// test module and use dependency injection to specify the client.
func application(client *dynago.Client) int {
	result, err := client.PutItem("mytable", doc).Execute()
	// do something with result maybe.
}

func TestApplication() {
	executor := &dynago.MockExecutor{}
	client := dynago.NewClient(executor)
	executor.PutItemResult = &dynago.PutItemResult{}

	// call into application
	application(client)

	// assert things on the executor.
	assert.Equal(true, executor.PutItemCalled)
	assert.Equal("mytable", executor.PutItemCall.Table)
	... and so on
}

func (*MockExecutor) BatchWriteItem 

func (e *MockExecutor) BatchWriteItem(batchWrite *BatchWrite) (*BatchWriteResult, error)

func (*MockExecutor) DeleteItem 

func (e *MockExecutor) DeleteItem(deleteItem *DeleteItem) (*DeleteItemResult, error)

func (*MockExecutor) GetItem 

func (e *MockExecutor) GetItem(getItem *GetItem) (*GetItemResult, error)

func (*MockExecutor) PutItem 

func (e *MockExecutor) PutItem(putItem *PutItem) (*PutItemResult, error)

func (*MockExecutor) Query 

func (e *MockExecutor) Query(query *Query) (*QueryResult, error)

func (*MockExecutor) Scan 

func (e *MockExecutor) Scan(scan *Scan) (*ScanResult, error)

func (*MockExecutor) SchemaExecutor 

func (e *MockExecutor) SchemaExecutor() SchemaExecutor

Currently we don't implement mocking for SchemaExecutor. Returns nil.

func (*MockExecutor) UpdateItem 

func (e *MockExecutor) UpdateItem(update *UpdateItem) (*UpdateItemResult, error)

type MockExecutorCall 

type MockExecutorCall struct {
	// used for all calls
	Method string
	Table  string

	// used for calls with expressions (most of them)
	ExpressionAttributeNames  map[string]string
	ExpressionAttributeValues Document

	Key                 Document
	Item                Document
	UpdateExpression    string
	ConditionExpression string
	ReturnValues        ReturnValues
	ConsistentRead      bool

	// Query and Scan
	IndexName              string
	KeyConditionExpression string
	FilterExpression       string
	ProjectionExpression   string
	Ascending              bool
	Limit                  uint
	ExclusiveStartKey      Document
	Select                 Select
	Segment                *int
	TotalSegments          *int

	BatchWrites BatchWriteTableMap
}

Mock executor calls

type Number 

type Number string

func (Number) FloatVal 

func (n Number) FloatVal() (float64, error)

func (Number) Int64Val 

func (n Number) Int64Val() (int64, error)

func (Number) IntVal 

func (n Number) IntVal() (int, error)

func (Number) Uint64Val 

func (n Number) Uint64Val() (uint64, error)

type NumberSet 

type NumberSet []string

type Param 

type Param struct {
	Key   string
	Value interface{}
}

func (Param) AsParams 

func (p Param) AsParams() []Param

Allows a solo Param to also satisfy the Params interface

type Params 

type Params interface {
	AsParams() []Param
}

Anything which implements Params can be used as expression parameters for dynamodb expressions.

DynamoDB item queries using expressions can be provided parameters in a number of handy ways: 

.Param(":k1", v1).Param(":k2", v2)
-or-
.Params(Param{":k1", v1}, Param{":k2", v2})
-or-
.FilterExpression("...", Param{":k1", v1}, Param{":k2", v2})
-or-
.FilterExpression("...", Document{":k1": v1, ":k2": v2})

Or any combination of Param, Document, or potentially other custom types which provide the Params interface.

type PutItem 

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

func (PutItem) ConditionExpression 

func (p PutItem) ConditionExpression(expression string, params ...Params) *PutItem

Set a ConditionExpression to do a conditional PutItem.

func (*PutItem) Execute 

func (p *PutItem) Execute() (res *PutItemResult, err error)

Actually Execute this putitem.

PutItemResult will be nil unless ReturnValues or ReturnConsumedCapacity is set.

func (PutItem) Param 

func (p PutItem) Param(key string, value interface{}) *PutItem

Set parameter for ConditionExpression

func (PutItem) Params 

func (p PutItem) Params(params ...Params) *PutItem

func (PutItem) ReturnValues 

func (p PutItem) ReturnValues(returnValues ReturnValues) *PutItem

Set ReturnValues.

type PutItemResult 

type PutItemResult struct {
	Attributes Document
}

type Query 

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

func (Query) ConsistentRead 

func (q Query) ConsistentRead(strong bool) *Query

If strong is true, do a strongly consistent read. (defaults to false)

func (Query) Desc 

func (q Query) Desc() *Query

Return results descending.

func (Query) ExclusiveStartKey 

func (q Query) ExclusiveStartKey(key Document) *Query

Set the start key (effectively the offset cursor)

func (*Query) Execute 

func (q *Query) Execute() (result *QueryResult, err error)

Execute this query and return results.

func (Query) FilterExpression 

func (q Query) FilterExpression(expression string, params ...Params) *Query

Set a post-filter expression for the results we scan.

func (Query) IndexName 

func (q Query) IndexName(name string) *Query

func (Query) KeyConditionExpression 

func (q Query) KeyConditionExpression(expression string, params ...Params) *Query

Set a condition expression on the key to narrow down what we scan

func (Query) Limit 

func (q Query) Limit(limit uint) *Query

Set the limit on results count.

Note that getting less than `limit` records doesn't mean you're at the last page of results, that can only be safely asserted if there is no LastEvaluatedKey on the result.

func (Query) Param 

func (q Query) Param(key string, value interface{}) *Query

Shortcut to set a single parameter for ExpressionAttributeValues.

func (Query) Params 

func (q Query) Params(params ...Params) *Query

Set a param, a document of params, or multiple params

func (Query) ProjectionExpression 

func (q Query) ProjectionExpression(expression string, params ...Params) *Query

Set a Projection Expression for controlling which attributes are returned.

func (Query) Select added in v1.1.2 

func (q Query) Select(value Select) *Query

Select specifies how attributes are chosen, or enables count mode.

Most of the time, specifying Select is not required, because the DynamoDB API does the "right thing" inferring values based on other attributes like the projection expression, index, etc.

type QueryResult 

type QueryResult struct {
	Items            []Document // All the items in the result
	Count            int        // The total number of items in the result
	ScannedCount     int        // How many items were scanned past to get the result
	LastEvaluatedKey Document   // The offset key for the next page.
	// contains filtered or unexported fields
}

The result returned from a query.

func (*QueryResult) Next 

func (qr *QueryResult) Next() (query *Query)

Helper for getting a query which will get the next page of results. Returns nil if there's no next page.

type ReturnValues 

type ReturnValues string
const (
	ReturnNone       ReturnValues = "NONE"
	ReturnAllOld     ReturnValues = "ALL_OLD"
	ReturnUpdatedOld ReturnValues = "UPDATED_OLD"
	ReturnAllNew     ReturnValues = "ALL_NEW"
	ReturnUpdatedNew ReturnValues = "UPDATED_NEW"
)

type Scan 

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

func (Scan) ExclusiveStartKey 

func (s Scan) ExclusiveStartKey(key Document) *Scan

func (*Scan) Execute 

func (s *Scan) Execute() (*ScanResult, error)

func (Scan) FilterExpression 

func (s Scan) FilterExpression(expression string, params ...Params) *Scan

func (Scan) IndexName 

func (s Scan) IndexName(name string) *Scan

func (Scan) Limit 

func (s Scan) Limit(limit uint) *Scan

func (Scan) ProjectionExpression 

func (s Scan) ProjectionExpression(expression string, params ...Params) *Scan

func (Scan) Segment 

func (s Scan) Segment(segment, total int) *Scan

Choose the parallel segment of the table to scan.

func (Scan) Select added in v1.1.2 

func (s Scan) Select(value Select) *Scan

Select specifies how attributes are chosen, or enables count mode.

Most of the time, specifying Select is not required, because the DynamoDB API does the "right thing" inferring values based on other attributes like the projection expression, index, etc.

type ScanResult 

type ScanResult struct {
	Items            []Document
	LastEvaluatedKey Document
	// contains filtered or unexported fields
}

func (*ScanResult) Next 

func (r *ScanResult) Next() *Scan

type SchemaExecutor 

type SchemaExecutor interface {
	CreateTable(*schema.CreateRequest) (*schema.CreateResult, error)
	DeleteTable(*schema.DeleteRequest) (*schema.DeleteResult, error)
	DescribeTable(*schema.DescribeRequest) (*schema.DescribeResponse, error)
	ListTables(*ListTables) (*schema.ListResponse, error)
}

type Select 

type Select string
const (
	SelectAllAttributes      Select = "ALL_ATTRIBUTES"
	SelectAllProjected       Select = "ALL_PROJECTED_ATTRIBUTES"
	SelectCount              Select = "COUNT"
	SelectSpecificAttributes Select = "SPECIFIC_ATTRIBUTES"
)

type StringSet 

type StringSet []string

type UpdateItem 

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

func (UpdateItem) ConditionExpression 

func (u UpdateItem) ConditionExpression(expression string, params ...Params) *UpdateItem

Set a condition expression for conditional update.

func (*UpdateItem) Execute 

func (u *UpdateItem) Execute() (res *UpdateItemResult, err error)

Execute this UpdateItem and return the result.

func (UpdateItem) Param 

func (u UpdateItem) Param(key string, value interface{}) *UpdateItem

Quick-set a single parameter

func (UpdateItem) Params 

func (u UpdateItem) Params(params ...Params) *UpdateItem

Set multiple parameters at once.

func (UpdateItem) ReturnValues 

func (u UpdateItem) ReturnValues(returnValues ReturnValues) *UpdateItem

If set, then we will get return values of either updated or old fields (see ReturnValues const)

func (UpdateItem) UpdateExpression 

func (u UpdateItem) UpdateExpression(expression string, params ...Params) *UpdateItem

Set an update expression to update specific fields and values.

type UpdateItemResult 

type UpdateItemResult struct {
	Attributes Document
}

Source Files

View all Source files

Directories

Path Synopsis
internal
aws
Provide AWS signature and other AWS-specific auth functions.
 Provide AWS signature and other AWS-specific auth functions.
codes
package codes defines the error types dynago maps.
 package codes defines the error types dynago maps.
dynamodb
package dynamodb maps information from dynamo itself, such as error tables and formats.
 package dynamodb maps information from dynamo itself, such as error tables and formats.

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