dynamo-client

dynamo-client

This is a low-level client for accessing DynamoDB from node.js. It offers a simpler and more node-friendly API than Amazon's SDK, in the style of @mikeal's popular request library.

Example

// assuming AWS credentials are available from process.ENV
var dynamo = require("dynamo-client")
  , region = "us-east-1"
  , db     = dynamo.createClient(region)

db.request("ListTables", null, function(err, data) {
  console.log(data.TableNames.length + " tables found.")
})

API

db = dynamo.createClient(region, [credentials])

This creates a database instance for the given DynamoDB region, which can be one of the following:

• us-east-1 (Northern Virginia)
• us-west-1 (Northern California)
• us-west-2 (Oregon)
• eu-west-1 (Ireland)
• ap-northeast-1 (Tokyo)
• ap-southeast-1 (Singapore)
• ap-southeast-2 (Sydney)
• sa-east-1 (Sao Paulo)

The official region list can be found in the AWS documentation.

You can also pass an object in here with host, port, region, version, and/or credentials parameters:

var db = dynamo.createClient({host: "localhost", port: 4567, version: "20111205"})

This is especially useful if you want to connect to a mock DynamoDB instance (such as FakeDynamo or ddbmock).

For backwards compatibility with versions <= 0.2.4, you can also pass the full host in here too (should detect most hostnames unless they're incredibly similar to an AWS region name):

var db = dynamo.createClient("dynamodb.eu-west-1.amazonaws.com")

Your AWS credentials (which can be found in your AWS console) can be specified in one of two ways:

• As the second argument, like this:

dynamo.createClient("us-east-1", {
  secretAccessKey: "<your-secret-access-key>",
  accessKeyId: "<your-access-key-id>"
})

• From process.env, such as like this:

export AWS_SECRET_ACCESS_KEY="<your-secret-access-key>"
export AWS_ACCESS_KEY_ID="<your-access-key-id>"

db.request(targetName, data, callback)

Database instances have only one method, request, which takes a target name, data object, and callback.

The target name can be any of the operations available for DynamoDB, which currently include the following:

• BatchGetItem
• BatchWriteItem
• CreateTable
• DeleteItem
• DeleteTable
• DescribeTable
• GetItem
• ListTables
• PutItem
• Query
• Scan
• UpdateItem
• UpdateTable

The data object needs to serialize into the DynamoDB JSON format.

The callback is called with the usual (err, data) signature, in which data is an object parsed from the JSON returned by DynamoDB.

To match AWS expectations, the following requests are automatically retried with exponential backoff (50ms, 100ms, 200ms, 400ms, etc) upon failure:

• 5xx errors
• 400 ThrottlingException errors
• 400 ProvisionedThroughputExceededException errors

Retries are attempted up to 10 times by default, but this amount can be changed by setting dynamo.Request.prototype.maxRetries to the desired number.