dynogels

Dynogels is a [DynamoDB][5] data mapper for [node.js][1]. This project has been forked from Vogels and republished to npm under a different name.

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 dynogels

Getting Started

First, you need to configure the [AWS SDK][2] with your credentials.

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

When running on EC2 it's recommended to leverage EC2 IAM roles. If you have configured your instance to use IAM roles, Vogels will automatically select these credentials for use in your application, and you do not need to manually provide credentials in any other format.

var dynogels = require('dynogels');
dynogels.AWS.config.update({region: "REGION"}); // region must be set

You can also directly pass in your access key id, secret and region. * It's recommended not to hard-code credentials inside an application. Use this method only for small personal scripts or for testing purposes.

var dynogels = require('dynogels');
dynogels.AWS.config.update({accessKeyId: 'AKID', secretAccessKey: 'SECRET', region: "REGION"});

Currently the following region codes are available in Amazon:

Code	Name
ap-northeast-1	Asia Pacific (Tokyo)
ap-southeast-1	Asia Pacific (Singapore)
ap-southeast-2	Asia Pacific (Sydney)
eu-central-1	EU (Frankfurt)
eu-west-1	EU (Ireland)
sa-east-1	South America (Sao Paulo)
us-east-1	US East (N. Virginia)
us-west-1	US West (N. California)
us-west-2	US West (Oregon)

Define a Model

Models are defined through the toplevel define method.

var Account = dynogels.define('Account', {
  hashKey : 'email',

  // add the timestamp attributes (updatedAt, createdAt)
  timestamps : true,

  schema : {
    email   : Joi.string().email(),
    name    : Joi.string(),
    age     : Joi.number(),
    roles   : dynogels.types.stringSet(),
    settings : {
      nickname      : Joi.string(),
      acceptedTerms : Joi.boolean().default(false)
    }
  }
});

Models can also be defined with hash and range keys.

var BlogPost = dynogels.define('BlogPost', {
  hashKey : 'email',
  rangeKey : ‘title’,
  schema : {
    email   : Joi.string().email(),
    title   : Joi.string(),
    content : Joi.binary(),
    tags   : dynogels.types.stringSet(),
  }
});

You can pass through validation options to Joi like so:

var BlogPost = dynogels.define('BlogPost', {
  hashKey : 'email',
  rangeKey : 'title',
  schema : {
    email   : Joi.string().email(),
    title   : Joi.string()
  },
  validation: {
    // allow properties not defined in the schema
    allowUnknown: true
  }
});

Create Tables for all defined models

dynogels.createTables(function(err) {
  if (err) {
    console.log('Error creating tables: ', err);
  } else {
    console.log('Tables has been created');
  }
});

When creating tables you can pass specific throughput settings or stream specification for any defined models.

dynogels.createTables({
  'BlogPost': {readCapacity: 5, writeCapacity: 10},
  'Account': {
    readCapacity: 20, 
    writeCapacity: 4, 
    streamSpecification: { 
      streamEnabled: true, 
      streamViewType: 'NEW_IMAGE' 
    }
  }
}, function(err) {
  if (err) {
    console.log('Error creating tables: ', err);
  } else {
    console.log('Tables has been created');
  }
});

You can also pass operational options using the $dynogels key:

• pollingInterval: When creating a table, Dynogels must poll the DynamoDB server to detect when table creation has completed. This option specifies the minimum poll interval, in milliseconds. (Default: 1000)

dynogels.createTables({
  $dynogels: { pollingInterval: 100 }
}, function(err) {
  if (err) {
    console.log('Error creating tables: ', err);
  } else {
    console.log('Tables has been created');
  }
});

Delete Table

BlogPost.deleteTable(function(err) {
  if (err) {
    console.log('Error deleting table: ', err);
  } else {
    console.log('Table has been deleted');
  }
});

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 = dynogels.define('Tweet', {
  hashKey : 'TweetID',
  timestamps : true,
  schema : {
    TweetID : dynogels.types.uuid(),
    content : Joi.string(),
  }
});

Configuration

You can configure dynogels to automatically add createdAt and updatedAt timestamp attributes when saving and updating a model. updatedAt will only be set when updating a record and will not be set on initial creation of the model.

var Account = dynogels.define('Account', {
  hashKey : 'email',

  // add the timestamp attributes (updatedAt, createdAt)
  timestamps : true,

  schema : {
    email : Joi.string().email(),
  }
});

If you want dynogels to handle timestamps, but only want some of them, or want your timestamps to be called something else, you can override each attribute individually:

var Account = dynogels.define('Account', {
  hashKey : 'email',

  // enable timestamps support
  timestamps : true,

  // I don't want createdAt
  createdAt: false,

  // I want updatedAt to actually be called updateTimestamp
  updatedAt: 'updateTimestamp'

  schema : {
    email : Joi.string().email(),
  }
});

You can override the table name the model will use.

var Event = dynogels.define('Event', {
  hashKey : 'name',
  schema : {
    name : Joi.string(),
    total : Joi.number()
  },

  tableName: 'deviceEvents'
});

if you set the tableName to a function, dynogels will use the result of the function as the active table to use. Useful for storing time series data.

var Event = dynogels.define('Event', {
  hashKey : 'name',
  schema : {
    name : Joi.string(),
    total : Joi.number()
  },

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

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
dynogels.dynamoDriver(dynamodb);

Saving Models to DynamoDB

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

Account.create({email: 'foo@example.com', 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: 'test@example.com', 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: 'werner@example.com',
  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'));
  });

Pass an array of items and they will be saved in parallel to DynamoDB.

var item1 = {email: 'foo1@example.com', name: 'Foo 1', age: 10};
var item2 = {email: 'foo2@example.com', name: 'Foo 2', age: 20};
var item3 = {email: 'foo3@example.com', name: 'Foo 3', age: 30};

Account.create([item1, item2, item3], function (err, acccounts) {
  console.log('created 3 accounts in DynamoDB', accounts);
});

Use expressions api to do conditional writes

  var params = {};
  params.ConditionExpression = '#i <> :x';
  params.ExpressionAttributeNames = {'#i' : 'id'};
  params.ExpressionAttributeValues = {':x' : 123};

  User.create({id : 123, name : 'Kurt Warner' }, params, function (error, acc) { ... });

Use the overwrite option to prevent over writing of existing records. * By default overwrite is set to true, allowing create operations to overwrite existing records

  // setting overwrite to false will generate
  // the same Condition Expression as in the previous example
  User.create({id : 123, name : 'Kurt Warner' }, {overwrite : false}, function (error, acc) { ... });

Updating

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

// update the name of the foo@example.com account
Account.update({email: 'foo@example.com', 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: 'foo@example.com', 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 22
Account.update({email: 'foo@example.com', 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: 'foo@example.com', age: null}, function (err, acc) {
  console.log('update account', acc.get('age')); // prints null
});

To ensure that an item exists before updating, use the expected parameter to check the existence of the hash key. The hash key must exist for every DynamoDB item. This will return an error if the item does not exist.

Account.update(
  { email: 'foo@example.com', name: 'FooBar Testers' },
  { expected: { email: { Exists: true } } },
  (err, acc) => {
    console.log(acc.get('name')); // FooBar Testers
  }
);

Account.update(
  { email: 'baz@example.com', name: 'Bar Tester' },
  { expected: { email: { Exists: true } } },
  (err, acc) => {
    console.log(err); // Condition Expression failed: no Account with that hash key
  }
);

This is essentially short-hand for:

var params = {};
    params.ConditionExpression = 'attribute_exists(#hashKey)';
    params.ExpressionAttributeNames = { '#hashKey' : 'email' };

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 : 'foo@example.com', age : {$add : 1}}, function (err, acc) {
  console.log('incremented age by 1', acc.get('age'));
});

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

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

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

Use the expressions api to update nested documents

var params = {};
  params.UpdateExpression = 'SET #year = #year + :inc, #dir.titles = list_append(#dir.titles, :title), #act[0].firstName = :firstName ADD tags :tag';
  params.ConditionExpression = '#year = :current';
  params.ExpressionAttributeNames = {
    '#year' : 'releaseYear',
    '#dir' : 'director',
    '#act' : 'actors'
  };

  params.ExpressionAttributeValues = {
    ':inc' : 1,
    ':current' : 2001,
    ':title' : ['The Man'],
    ':firstName' : 'Rob',
    ':tag' : dynogels.Set(['Sports', 'Horror'], 'S')
  };

Movie.update({title : 'Movie 0', description : 'This is a description'}, params, function (err, mov) {});

Deleting

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

```js Account.destroy('foo@example.com', function (err) { console.log('account deleted'); });

// Destroy model using h