vogels

vogels is a DynamoDB data mapper for node.js.

Features

• Simplified data modeling and mapping to DynamoDB types
• Advanced chainable apis for query and scan operations
• Data validation
• Autogenerating UUIDs
• Global Secondary Indexes
• Local Secondary Indexes
• Parallel Scans

Installation

npm install vogels

Getting Started

First, you need to configure the AWS SDK with your credentials.

var vogels = require('vogels');
vogels.AWS.config.loadFromPath('credentials.json');

You can also directly pass in your access key id and secret

var vogels = require('vogels');
vogels.AWS.config.update({accessKeyId: 'AKID', secretAccessKey: 'SECRET'});

Define a Model

Models are defined through the toplevel define method.

var Account = vogels.define('Account', function (schema) {
  schema.String('email', {hashKey: true});
  schema.String('name').required(); // name attribute is required
  schema.Number('age'); // age is optional
  schema.Date('created', {default: Date.now});
});

Models can also be defined with hash and range keys.

var BlogPost = vogels.define('Account', function (schema) {
  schema.String('email', {hashKey: true});
  schema.String('title', {rangeKey: true});
  schema.String('content');
  schema.StringSet('tags');
});

Schema Types

Vogels provides the following schema types:

• String
• Number
• StringSet
• NumberSet
• Boolean
• Date
• UUID
• TimeUUID

UUID

UUIDs can be declared for any attributes, including hash and range keys. By Default, the uuid will be automatically generated when attempting to create the model in DynamoDB.

var Tweet = vogels.define('Account', function (schema) {
  schema.UUID('TweetID', {hashKey: true});
  schema.String('content');
  schema.Date('created', {default: Date.now});
});

Configuration

After you've defined your model you can configure the table name to use. By default, the table name used will be the lowercased and pluralized version of the name you provided when defining the model.

Account.config({tableName: 'AccountsTable'});

You can also pass in a custom instance of the aws-sdk DynamoDB client

var dynamodb = new AWS.DynamoDB();
Account.config({dynamodb: dynamodb});

// or globally use custom DynamoDB instance
// all defined models will now use this driver
vogels.dynamoDriver(dynamodb);

Saving Models to DynamoDB

With your models defined, we can start saving them to DynamoDB.

Account.create({email: '[email protected]', name: 'Foo Bar', age: 21}, function (err, acc) {
  console.log('created account in DynamoDB', acc.get('email'));
});

You can also first instantiate a model and then save it.

var acc = new Account({email: '[email protected]', name: 'Test Example'});
acc.save(function (err) {
  console.log('created account in DynamoDB', acc.get('email'));
});

Saving models that require range and hashkeys are identical to ones with only hashkeys.

BlogPost.create({
  email: '[email protected]', 
  title: 'Expanding the Cloud', 
  content: 'Today, we are excited to announce the limited preview...'
  }, function (err, post) {
    console.log('created blog post', post.get('title'));
  });

Updating

When updating a model the hash and range key attributes must be given, all other attributes are optional

// update the name of the [email protected] account
Account.update({email: '[email protected]', name: 'Bar Tester'}, function (err, acc) {
  console.log('update account', acc.get('name'));
});

Model.update accepts options to pass to DynamoDB when making the updateItem request

Account.update({email: '[email protected]', name: 'Bar Tester'}, {ReturnValues: 'ALL_OLD'}, function (err, acc) {
  console.log('update account', acc.get('name')); // prints the old account name
});

// Only update the account if the current age of the account is 21
Account.update({email: '[email protected]', name: 'Bar Tester'}, {expected: {age: 22}}, function (err, acc) {
  console.log('update account', acc.get('name'));
});

// setting an attribute to null will delete the attribute from DynamoDB
Account.update({email: '[email protected]', age: null}, function (err, acc) {
  console.log('update account', acc.get('age')); // prints null
});

You can also pass what action to perform when updating a given attribute Use $add to increment or decrement numbers and add values to sets

Account.update({email : '[email protected]', age : {$add : 1}}, function (err, acc) {
  console.log('incremented age by 1', acc.get('age'));
});

BlogPost.update({
  email : '[email protected]',
  title : 'Expanding the Cloud',
  tags  : {$add : 'cloud'}
}, function (err, post) {
  console.log('added single tag to blog post', post.get('tags'));
});

BlogPost.update({
  email : '[email protected]',
  title : 'Expanding the Cloud',
  tags  : {$add : ['cloud', 'dynamodb']}
}, function (err, post) {
  console.log('added tags to blog post', post.get('tags'));
});

$del will remove values from a given set

BlogPost.update({
  email : '[email protected]',
  title : 'Expanding the Cloud',
  tags  : {$del : 'cloud'}
}, function (err, post) {
  console.log('removed cloud tag from blog post', post.get('tags'));
});

BlogPost.update({
  email : '[email protected]',
  title : 'Expanding the Cloud',
  tags  : {$del : ['aws', 'node']}
}, function (err, post) {
  console.log('removed multiple tags', post.get('tags'));
});

Deleting

You delete items in DynamoDB using the hashkey of model If your model uses both a hash and range key, than both need to be provided

Account.destroy('[email protected]', function (err) {
  console.log('account deleted');
});

// Destroy model using hash and range key
BlogPost.destroy('[email protected]', 'Hello World!', function (err) {
  console.log('post deleted')
});

BlogPost.destroy({email: '[email protected]', title: 'Another Post'}, function (err) {
  console.log('another post deleted')
});

Model.destroy accepts options to pass to DynamoDB when making the deleteItem request

Account.destroy('[email protected]', {ReturnValues: true}, function (err, acc) {
  console.log('account deleted');
  console.log('deleted account name', acc.get('name'));
});

Account.destroy('[email protected]', {expected: {age: 22}}, function (err) {
  console.log('account deleted if the age was 22');

Loading models from DynamoDB

The simpliest way to get an item from DynamoDB is by hashkey.

Account.get('[email protected]', function (err, acc) {
  console.log('got account', acc.get('email'));
});

Perform the same get request, but this time peform a consistent read.

Account.get('[email protected]', {ConsistentRead: true}, function (err, acc) {
  console.log('got account', acc.get('email'));
});

Model.get accepts any options that DynamoDB getItem request supports. For example:

Account.get('[email protected]', {ConsistentRead: true, AttributesToGet : ['name','age']}, function (err, acc) {
  console.log('got account', acc.get('email'))
  console.log(acc.get('name'));
  console.log(acc.get('age'));
  console.log(acc.get('email')); // prints null
});

Get a model using hash and range key.

// load up blog post written by Werner, titled DynamoDB Keeps Getting Better and cheaper
BlogPost.get('[email protected]', 'dynamodb-keeps-getting-better-and-cheaper', function (err, post) {
  console.log('loaded post by range and hash key', post.get('content'));
});

Model.get also supports passing an object which contains hash and range key attributes to load up a model

BlogPost.get({email: '[email protected]', title: 'Expanding the Cloud'}, function (err, post) {
  console.log('loded post', post.get('content'));
});

Query

For models that use hash and range keys Vogels provides a flexible and chainable query api

// query for blog posts by [email protected]
BlogPost
  .query('[email protected]')
  .exec(callback);

// same as above, but load all results
BlogPost
  .query('[email protected]')
  .loadAll()
  .exec(callback);

// only load the first 5 posts by werner
BlogPost
  .query('[email protected]')
  .limit(5)
  .exec(callback);

// query for posts by werner where the tile begins with 'Expanding'
BlogPost
  .query('[email protected]')
  .where('title').beginsWith('Expanding')
  .exec(callback);

// return only the count of documents that begin with the title Expanding
BlogPost
  .query('[email protected]')
  .where('title').beginsWith('Expanding')
  .select('COUNT')
  .exec(callback);

// only return title and content attributes of 10 blog posts
// that begin with the title Expanding
BlogPost
  .query('[email protected]')
  .where('title').beginsWith('Expanding')
  .attriubutes(['title', 'content'])
  .limit(10)
  .exec(callback);

// sorting by title ascending
BlogPost
  .query('[email protected]')
  .ascending()
  .exec(callback)

// sorting by title descending
BlogPost
  .query('[email protected]')
  .descending()
  .exec(callback)

// All query options are chainable
BlogPost
  .query('[email protected]')
  .where('title').gt('Expanding')
  .attriubutes(['title', 'content'])
  .limit(10)
  .ascending()
  .loadAll()
  .exec(callback);

Vogels supports all the possible KeyConditions that DynamoDB currently supports.

BlogPost
  .query('[email protected]')
  .where('title').equals('Expanding')
  .exec();

// less than equals
BlogPost
  .query('[email protected]')
  .where('title').lte('Expanding')
  .exec();

// less than
BlogPost
  .query('[email protected]')
  .where('title').lt('Expanding')
  .exec();

// greater than
BlogPost
  .query('[email protected]')
  .where('title').gt('Expanding')
  .exec();

// greater than equals
BlogPost
  .query('[email protected]')
  .where('title').gte('Expanding')
  .exec();

BlogPost
  .query('[email protected]')
  .where('title').beginsWith('Expanding')
  .exec();

BlogPost
  .query('[email protected]')
  .where('title').between(['[email protected]', '[email protected]'])
  .exec();

Query Filters allow you to further filter results on non-key attributes.

BlogPost
  .query('[email protected]')
  .where('title').equals('Expanding')
  .filter('tags').contains('cloud')
  .exec();

See the queryFilter.js example for more examples of using query filters

Global Indexes

First, define a model with a global secondary index.

var GameScore = vogels.define('GameScore', function (schema) {
  schema.String('userId', {hashKey: true});
  schema.String('gameTitle', {rangeKey: true});
  schema.Number('topScore');
  schema.Date('topScoreDateTime');
  schema.Number('wins');
  schema.Number('losses');

  schema.globalIndex('GameTitleIndex', { hashKey: 'gameTitle', rangeKey: 'topScore'});
});

Now we can query against the global index

GameScore
  .query('Galaxy Invaders')
  .usingIndex('GameTitleIndex')
  .descending()
  .exec(callback);

When can also configure the attributes projected into the index. By default all attributes will be projected when no Projection pramater is present

var GameScore = vogels.define('GameScore', function (schema) {
  schema.String('userId', {hashKey: true});
  schema.String('gameTitle', {rangeKey: true});
  schema.Number('topScore');
  schema.Date('topScoreDateTime');
  schema.Number('wins');
  schema.Number('losses');

  schema.globalIndex('GameTitleIndex', {
    hashKey: 'gameTitle',
    rangeKey: 'topScore',
    Projection: { NonKeyAttributes: [ 'wins' ], ProjectionType: 'INCLUDE' } //optional, defaults to ALL
  });
});

Filter items against the configured rangekey for the global index.

GameScore
  .query('Galaxy Invaders')
  .usingIndex('GameTitleIndex')
  .where('topScore').gt(1000)
  .descending()
  .exec(function (err, data) {
    console.log(_.map(data.Items, JSON.stringify));
  });

Local Secondary Indexes

First, define a model using a local secondary index

var BlogPost = vogels.define('Account', function (schema) {
  schema.String('email', {hashKey: true});
  schema.String('title', {rangeKey: true});
  schema.String('content');

  schema.Date('PublishedDateTime', {secondaryIndex: true});
});

Now we can query for blog posts using the secondary index

BlogPost
  .query('[email protected]')
  .usingIndex('PublishedDateTimeIndex')
  .descending()
  .exec(callback);

Could also query for published posts, but this time return oldest first

BlogPost
  .query('[email protected]')
  .usingIndex('PublishedDateTimeIndex')
  .ascending()
  .exec(callback);

Finally lets load all published posts sorted by publish date

BlogPost
  .query('[email protected]')
  .usingIndex('PublishedDateTimeIndex')
  .descending()
  .loadAll()
  .exec(callback);

Learn more about secondary indexes

Scan

Vogels provides a flexible and chainable api for scanning over all your items This api is very similar to the query api.

// scan all accounts, returning the first page or results
Account.scan().exec(callback);

// scan all accounts, this time loading all results
// note this will potentially make several calls to DynamoDB 
// in order to load all results
Account
  .scan()
  .loadAll()
  .exec(callback);

// Load 20 accounts
Account
  .scan()
  .limit(20)
  .exec();

// Load All accounts, 20 at a time per request
Account
  .scan()
  .limit(20)
  .loadAll()
  .exec();

// Load accounts which match a filter
// only return email and created attributes
// and return back the consumed capacity the request took
Account
  .scan()
  .where('email').gte('[email protected]')
  .attributes(['email','created'])
  .returnConsumedCapacity()
  .exec();

// Returns number of matching accounts, rather than the matching accounts themselves
Account
  .scan()
  .where('age').gte(21)
  .select('COUNT')
  .exec();

// Start scan using start key
Account
  .scan()
  .where('age').notNull()
  .startKey('[email protected]')
  .exec()

Vogels supports all the possible Scan Filters that DynamoDB currently supports.

// equals
Account
  .scan()
  .where('name').equals('Werner')
  .exec();

// not equals
Account
  .scan()
  .where('name').ne('Werner')
  .exec();

// less than equals
Account
  .scan()
  .where('name').lte('Werner')
  .exec();

// less than
Account
  .scan()
  .where('name').lt('Werner')
  .exec();

// greater than equals
Account
  .scan()
  .where('name').gte('Werner')
  .exec();

// greater than
Account
  .scan()
  .where('name').gt('Werner')
  .exec();

// name attribute doesn't exist
Account
  .scan()
  .where('name').null()
  .exec();

// name attribute exists
Account
  .scan()
  .where('name').notNull()
  .exec();

// contains
Account
  .scan()
  .where('name').contains('ner')
  .exec();

// not contains
Account
  .scan()
  .where('name').notContains('ner')
  .exec();

// in
Account
  .scan()
  .where('name').in(['[email protected]', '[email protected]'])
  .exec();

// begins with
Account
  .scan()
  .where('name').beginsWith('Werner')
  .exec();

// between
Account
  .scan()
  .where('name').between(['Bar', 'Foo'])
  .exec();

// multiple filters
Account
  .scan()
  .where('name').equals('Werner')
  .where('age').notNull()
  .exec();

Parallel Scan

Parallel scans increase the throughput of your table scans. The parallel scan operation is identical to the scan api. The only difference is you must provide the total number of segments

Caution you can easily consume all your provisioned throughput with this api

var totalSegments = 8;

Account.parallelScan(totalSegments)
  .where('age').gte(18)
  .attributes('age')
  .exec(callback);

// Load All accounts
Account
  .parallelScan(totalSegments)
  .exec()

More info on Parallel Scans

Batch Get Items

Model.getItems allows you to load multiple models with a single request to DynamoDB.

DynamoDB limits the number of items you can get to 100 or 1MB of data for a single request. Vogels automatically handles splitting up into multiple requests to load all items.

Account.getItems(['[email protected]','[email protected]', '[email protected]'], function (err, accounts) {
  console.log('loaded ' + accounts.length + ' accounts'); // prints loaded 3 accounts
});

// For models with range keys you must pass in objects of hash and range key attributes
var postKey1 = {email : '[email protected]', title : 'Hello World!'};
var postKey2 = {email : '[email protected]', title : 'Another Post'};

BlogPost.getItems([postKey1, postKey2], function (err, posts) {
  console.log('loaded posts');
});

Model.getItems accepts options which will be passed to DynamoDB when making the batchGetItem request

// Get both accounts, using a consistent read
Account.getItems(['[email protected]','[email protected]'], {ConsistentRead: true}, function (err, accounts) {
  console.log('loaded ' + accounts.length + ' accounts'); // prints loaded 2 accounts
});

Streaming api

vogels supports a basic streaming api in addition to the callback api for query, scan, and parallelScan operations.

var stream = Account.parallelScan(4).exec();

stream.on('readable', function () {
  console.log('single parallel scan response', stream.read());
});

stream.on('end', function () {
  console.log('Parallel scan of accounts finished');
});

var querystream = BlogPost.query('[email protected]').loadAll().exec();

querystream.on('readable', function () {
  console.log('single query response', stream.read());
});

querystream.on('end', function () {
  console.log('query for blog posts finished');
});

Dynamic Table Names

vogels supports dynamic table names, useful for storing time series data.

var Event = vogels.define('Event', function (schema) {
  schema.String('name', {hashKey: true});
  schema.Number('total');

  // store monthly event data
  schema.tableName = function () {
    var d = new Date();
    return ['events', d.getFullYear(), d.getMonth() + 1].join('_');
  };
});

Examples

var vogels = require('vogels');

var Account = vogels.define('Account', function (schema) {
  schema.String('email', {hashKey: true});
  schema.String('name').required();
  schema.Number('age');
  schema.Date('created', {default: Date.now});
});

Account.create({email: '[email protected]', name : 'Test Account'}, function (err, acc) {
  console.log('created account at', acc.get('created')); // prints created Date

  acc.set({age: 22});

  acc.update(function (err) {
    console.log('updated account age');
  });

});

See the examples for more working sample code.

TODO

• Batch Write Items
• Streaming api support for all operations
• DDL operations (update throughput)
• Full intergration test suite

License

(The MIT License)

Copyright (c) 2014 Ryan Fitzgerald

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.