@traverse-data/sails-dynamodb NPM

sails-dynamodb

A Waterline adapter for DynamoDB. May be used in a Sails app or anything using Waterline for the ORM.

_Note: This adapter support the Sails.js v0.10.x. check 0.9 branch if you use before v0.10

Install

Install is through NPM.

$ sails new project && cd project
$ npm install sails-dynamodb --save

Add your amazon keys to your adapter config

Configuration

The following config options are available along with their default values:

config/connection.js

module.exports.adapters = {

  // If you leave the adapter config unspecified 
  // in a model definition, 'default' will be used.
  localDiskDb: {
    adapter: 'sails-disk'
  },
  
  dynamoDb: {
    adapter: "sails-dynamodb",
    accessKeyId: process.env.DYNAMO_ACCESS_KEY_ID,
    secretAccessKey: process.env.DYNAMO_SECRET_ACCESS_KEY,
    region: "us-west-1",
    endPoint: "http://localhost:8000", // Optional: add for DynamoDB local
  },
  
};

config/models.js

module.exports.adapters = {

  // If you leave the adapter config unspecified 
  // in a model definition, 'default' will be used.
  connection: 'dynamoDb'
  
};

Find

Support for where is added as following:

  ?where={"name":{"null":true}}
  ?where={"name":{"notNull":true}}
  ?where={"name":{"equals":"firstName lastName"}}
  ?where={"name":{"ne":"firstName lastName"}}
  ?where={"name":{"lte":"firstName lastName"}}
  ?where={"name":{"lt":"firstName lastName"}}
  ?where={"name":{"gte":"firstName lastName"}}
  ?where={"name":{"gt":"firstName lastName"}}
  ?where={"name":{"contains":"firstName lastName"}}
  ?where={"name":{"contains":"firstName lastName"}}
  ?where={"name":{"beginsWith":"firstName"}}
  ?where={"name":{"in":["firstName lastName", "another name"]}}
  ?where={"name":{"between":["firstName", "lastName"]}}

You can specify what attributes/keys should be returned from the query as following:

  //This will return only name and age in the result (if the field exists in the result)
  ?where={"name":{"equals":"firstName lastName"}, "select": ["name","age"]}

Pagination

NOTE: skip is not supported!

Support for Pagination is done using DynamoDB's LastEvaluatedKey and passing that to ExclusiveStartKey. See: DynamoDB Documentation

First add a limit to current request

/user?limit=2

Then get the last primaryKey value and send it as startKey in the next request

/user?limit=2&startKey={"PrimaryKey": "2"}

For more complex queries, you must provide all the fields that are used for an index of the last object returned. An example not using the blueprint apis below. Assume there is a GSI on email (hash) and loginDate (range).

// Looking for recent logins by a specific email address
UserLogins.find({
  where: {
    email: 'someone@like.you'
    loginDate: {"lt": new Date().toISOString()}
  },
  limit: 10
}).exec((err, userLogins) => {
  UserLogins.find({
    where: {
      email: 'someone@like.you'
      loginDate: {"lt": new Date().toISOString()},
      startKey: {
        email: 'someone@like.you',
        loginDate: userLogins[userLogins.length - 1].loginDate
      }
    },
    limit: 10
  }).exec((err, moreUserLogins) => {
    doSomethingWithLogins(userLogins.concat(moreUserLogins));
  });
});

See that the startKey is in the where block and that it has both fields of the Global Secondary Index.

Using DynamoDB Indexes

Primary hash/range keys, local secondary indexes, and global secondary indexes are currently supported by this adapter, but their usage is always inferred from query conditions–Model.find will attempt to use the most optimal index using the following precedence:

Primary hash and range > primary hash and secondary range > global secondary hash and range
> primary hash > global secondary hash > no index/primary

If an index is being used and there are additional query conditions, then results are compiled using DynamoDB's result filtering. If no index can be used for a query, then the adapter will perform a scan on the table for results.

Adding Indexes

Primary hash and primary range

UserId: {
  type: 'integer',
  primaryKey: 'hash'
},
GameTitle: {
  type: 'string',
  primaryKey: 'range'
}

Secondary range (local secondary index)

The index name used for a local secondary index is the name of the field suffixed by "Index". In this case the index name is TimeIndex.

Time: {
  type: 'datetime',
  index: 'secondary'
}

Global secondary index

The index name used for a global secondary index is specified in the index property before the type of key (hash or range). In this case the index name is GameTitleIndex.

GameTitle: {
  type: 'string',
  index: 'GameTitleIndex-hash'
},
HighScore: {
  type: 'integer',
  index: 'GameTitleIndex-range'
}

Fields with multiple indexes

A field can be both the primary and part of a GSI index. Participating in multiple GSI indexes is supported as of v0.12.5.

GameTitle: {
  type: 'string',
  primaryKey: 'hash'
  index: 'GameTitleIndex-hash'
}

Multiple GSIs:

GameTitle: {
  type: 'string',
  primaryKey: 'hash'
  index: ['GameTitleIndex-hash', 'SomeOtherIndex-hash']
}

Multiple GSIs and a secondary index:

GameTitle: {
  type: 'string',
  primaryKey: 'hash'
  index: ['secondary', 'GameTitleIndex-hash', 'SomeOtherIndex-hash']
}

Sorting By Indexes

Sorting does not look like how it looks with the normal sails database adapters. You can not sort by an arbitrary field, you must sort by a range field in an index. The index is automatically inferred by what you are querying and you can specify a direction to sort the range fields of the used index. Using the GSI defined above, this will query for descending highscores of Super Mario World:

GameScores.find({
  where: {
    GameTitle: "Super Mario World"
  },
  sort: "-1"
})

Update

The Model.update method is currently expected to update exactly one item since DynamoDB only offers an UpdateItem endpoint. A complete primary key must be supplied. Any additional "where" conditions passed to Model.update are used to build a conditional expression for the update. Despite the fact the DynamoDB updates only one item, Model.update will always return an array of the (one or zero) updated items upon success.

Testing

Test are written with mocha. Integration tests are handled by the waterline-adapter-tests project, which tests adapter methods against the latest Waterline API.

To run tests:

$ npm test

About Sails.js and Waterline

http://sailsjs.org

Waterline is a new kind of storage and retrieval engine for Sails.js. It provides a uniform API for accessing stuff from different kinds of databases, protocols, and 3rd party APIs. That means you write the same code to get users, whether they live in mySQL, LDAP, MongoDB, or Facebook.

image_squidhome@2x.png

License

The MIT License (MIT)

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.