dynamodb-examples-using-tables.md

Creating and Using Tables in DynamoDB

This Node.js code example shows:

• How to create and manage tables used to store and retrieve data from DynamoDB.

The Scenario

Similar to other database systems, DynamoDB stores data in tables. A DynamoDB table is a collection of data that's organized into items that are analogous to rows. To store or access data in DynamoDB, you create and work with tables.

In this example, you use a series of Node.js modules to perform basic operations with a DynamoDB table. The code uses the SDK for JavaScript to create and work with tables by using these methods of the AWS.DynamoDB client class:

• createTable

• listTables

• describeTable

• deleteTable

Prerequisite Tasks

To set up and run this example, first complete these tasks:

• Install Node.js. For more information, see the Node.js website.

• Create a shared configurations file with your user credentials. For more information about providing a shared credentials file, see Loading Credentials in Node.js from the Shared Credentials File.

Configuring the SDK

Configure the SDK for JavaScript by creating a global configuration object then setting the region for your code. In this example, the region is set to us-west-2.

// Load the SDK for JavaScript
var AWS = require('aws-sdk');
// Set the region 
AWS.config.update({region: 'us-west-2'});

Creating a Table

Create a Node.js module with the file name ddb_createtable.js. Be sure to configure the SDK as previously shown. To access DynamoDB, create an AWS.DynamoDB service object. Create a JSON object containing the parameters needed to create a table, which in this example includes the name and data type for each attribute, the key schema, the name of the table, and the units of throughput to provision. Call the createTable method of the DynamoDB service object.

// Load the AWS SDK for Node.js
var AWS = require('aws-sdk');
// Set the region 
AWS.config.update({region: 'REGION'});

// Create the DynamoDB service object
ddb = new AWS.DynamoDB({apiVersion: '2012-10-08'});

var params = {
  AttributeDefinitions: [
    {
      AttributeName: 'CUSTOMER_ID',
      AttributeType: 'N'
    },
    {
      AttributeName: 'CUSTOMER_NAME',
      AttributeType: 'S'
    }
  ],
  KeySchema: [
    {
      AttributeName: 'CUSTOMER_ID',
      KeyType: 'HASH'
    },
    {
      AttributeName: 'CUSTOMER_NAME',
      KeyType: 'RANGE'
    }
  ],
  ProvisionedThroughput: {
    ReadCapacityUnits: 1,
    WriteCapacityUnits: 1
  },
  TableName: 'CUSTOMER_LIST',
  StreamSpecification: {
    StreamEnabled: false
  }
};

// Call DynamoDB to create the table
ddb.createTable(params, function(err, data) {
  if (err) {
    console.log("Error", err);
  } else {
    console.log("Success", data.Table.KeySchema);
  }
});

To run the example, type the following at the command line.

node ddb_createtable.js

This sample code can be found here on GitHub.

Listing Your Tables

Create a Node.js module with the file name ddb_listtables.js. Be sure to configure the SDK as previously shown. To access DynamoDB, create an AWS.DynamoDB service object. Create a JSON object containing the parameters needed to list your tables, which in this example limits the number of tables listed to 10. Call the listTables method of the DynamoDB service object.

// Load the AWS SDK for Node.js
var AWS = require('aws-sdk');
// Set the region 
AWS.config.update({region: 'REGION'});

// Create the DynamoDB service object
ddb = new AWS.DynamoDB({apiVersion: '2012-10-08'});

// Call DynamoDB to retrieve the list of tables
ddb.listTables({Limit: 10}, function(err, data) {
  if (err) {
    console.log("Error", err.code);
  } else {
    console.log("Table names are ", data.TableNames);
  }
});

To run the example, type the following at the command line.

node ddb_listtables.js

This sample code can be found here on GitHub.

Describing a Table

Create a Node.js module with the file name ddb_describetable.js. Be sure to configure the SDK as previously shown. To access DynamoDB, create an AWS.DynamoDB service object. Create a JSON object containing the parameters needed to describe a table, which in this example includes the name of the table provided as a command-line parameter. Call the describeTable method of the DynamoDB service object.

// Load the AWS SDK for Node.js
var AWS = require('aws-sdk');
// Set the region 
AWS.config.update({region: 'REGION'});

// Create the DynamoDB service object
ddb = new AWS.DynamoDB({apiVersion: '2012-10-08'});

var params = {
  TableName: process.argv[2]
};

// Call DynamoDB to retrieve the selected table descriptions
ddb.describeTable(params, function(err, data) {
  if (err) {
    console.log("Error", err);
  } else {
    console.log("Success", data.Table.KeySchema);
  }
});

To run the example, type the following at the command line.

node ddb_describetable.js TABLE_NAME

This sample code can be found here on GitHub.

Deleting a Table

Create a Node.js module with the file name ddb_deletetable.js. Be sure to configure the SDK as previously shown. To access DynamoDB, create an AWS.DynamoDB service object. Create a JSON object containing the parameters needed to describe a table, which in this example includes the name of the table provided as a command-line parameter. Call the deleteTable method of the DynamoDB service object.

// Load the AWS SDK for Node.js
var AWS = require('aws-sdk');
// Set the region 
AWS.config.update({region: 'REGION'});

// Create the DynamoDB service object
ddb = new AWS.DynamoDB({apiVersion: '2012-10-08'});

var params = {
  TableName: process.argv[2]
};

// Call DynamoDB to delete the specified table
ddb.deleteTable(params, function(err, data) {
  if (err && err.code === 'ResourceNotFoundException') {
    console.log("Error: Table not found");
  } else if (err && err.code === 'ResourceInUseException') {
    console.log("Error: Table in use");
  } else {
    console.log("Success", data);
  }
});

To run the example, type the following at the command line.

node ddb_deletetable.js TABLE_NAME

This sample code can be found here on GitHub.