feathers-memory

feathers-memory

An in memory CRUD service for Feathers.

Installation

npm install feathers-memory --save

Getting Started

You can create an in-memory service with no options:

var memory = require('feathers-memory');
app.use('/todos', memory());

This will create a todos datastore with the default configuration.

Complete Example

Here is an example of a Feathers server with a todos in-memory service that supports pagination:

// app.js
var feathers = require('feathers');
var bodyParser = require('body-parser');
var memory = require('feathers-memory');

// Create a feathers instance.
var app = feathers()
  // Enable Socket.io
  .configure(feathers.socketio())
  // Enable REST services
  .configure(feathers.rest())
  // Turn on JSON parser for REST services
  .use(bodyParser.json())
  // Turn on URL-encoded parser for REST services
  .use(bodyParser.urlencoded({ extended: true }));

// Create an in-memory Feathers service with a default page size of 2 items
// and a maximum size of 4
app.use('/todos', memory({
  paginate: {
    default: 2,
    max: 4
  }
}));

// Create a dummy Todo
app.service('todos').create({
  text: 'Server todo',
  complete: false
}).then(function(todo) {
  console.log('Created todo', todo);
});

// Start the server.
var port = 3030;

app.listen(port, function() {
  console.log('Feathers server listening on port ' + port);
});

You can run this example by using node examples/app and going to localhost:3030/todos. You will see the test Todo that we created at the end of that file.

Extending

There are several ways to extend the basic CRUD functionality of this service.

Keep in mind that calling the original service methods will return a Promise that resolves with the value.

feathers-hooks

The most flexible option is weaving in functionality through feathers-hooks, for example, createdAt and updatedAt timestamps could be added like this:

var feathers = require('feathers');
var hooks = require('feathers-hooks');
var memory = require('feathers-memory');

var app = feathers()
  .configure(hooks())
  .use('/todos', memory({
    paginate: {
      default: 2,
      max: 4
    }
  }));

var stripIds = function() {
  delete hook.data.id;
  next();
}

var updateTimestamp = function(hook, next) {
  hook.data.updatedAt = new Date();
  next();
}

app.service('todos').before({
  // You can create a single hook like this
  create: function(hook, next) {
    hook.data.createdAt = new Date();
    next();
  },

  // Or you can chain multiple hooks like this
  update: [stripIds, updateTimeStamp]
});

app.listen(3030);

Classes (ES6)

The module also exports a Babel transpiled ES6 class as Service that can be directly extended like this:

import { Service } from 'feathers-memory';

class MyService extends Service {
  create(data, params) {
    data.created_at = new Date();

    return super.create(data, params).then(todo);
  }
}

app.use('/todos', new MyService({
  paginate: {
    default: 2,
    max: 4
  }
}));

Uberproto (ES5)

You can also use .extend on a service instance (extension is provided by Uberproto):

var myService = memory({
  paginate: {
    default: 2,
    max: 4
  }
}).extend({
  create: function(data) {
    data.created_at = new Date();
    return this._super.apply(this, arguments);
  }
});

app.use('/todos', myService);

Note: this is more for backwards compatibility. We recommend the usage of hooks as they are easier to test, easier to maintain and are more flexible.

Options

The following options can be passed when creating a new memory service:

• idField - The name of the id field property. Default is id
• startId - An id number to start with that will be incremented for new record (default: 0)
• store - An object with id to item assignments to pre-initialize the data store
• paginate - A pagination object containing a default and max page size (see below)

Pagination

When initializing the service you can set the following pagination options in the paginate object:

• default - Sets the default number of items
• max - Sets the maximum allowed number of items per page (even if the $limit query parameter is set higher)

When paginate.default is set, find will return an object (instead of the normal array) in the following form:

{
  "total": "<total number of records>",
  "limit": "<max number of items per page>",
  "skip": "<number of skipped items (offset)>",
  "data": [/* data */]
}

Query Parameters

The find API allows the use of $limit, $skip, $sort, and $select in the query. These special parameters can be passed directly inside the query object:

// Find all recipes that include salt, limit to 10, only include name field.
{"ingredients":"salt", "$limit":10, "$select": ["name"] } } // JSON

GET /?ingredients=salt&$limit=10&$select[]=name // HTTP

As a result of allowing these to be put directly into the query string, you won't want to use $limit, $skip, $sort, or $select as the name of fields in your document schema.

$limit

$limit will return only the number of results you specify:

// Retrieves the first two records found where age is 37.
query: {
  age: 37,
  $limit: 2
}

$skip

$skip will skip the specified number of results:

// Retrieves all except the first two records found where age is 37.
query: {
  age: 37,
  $skip: 2
}

$sort

$sort will sort based on the object you provide:

// Retrieves all where age is 37, sorted ascending alphabetically by name.
query: {
  age: 37,
  $sort: { name: 1 }
}

// Retrieves all where age is 37, sorted descending alphabetically by name.
query: {
  age: 37,
  $sort: { name: -1}
}

$select

$select support in a query allows you to pick which fields to include or exclude in the results.

// Only retrieve name.
query: {
  name: 'Alice',
  $select: {'name': 1}
}

// Retrieve everything except age.
query: {
  name: 'Alice',
  $select: {'age': 0}
}

Filter criteria

In addition to sorting and pagination, properties can also be filtered by criteria. Standard criteria can just be added to the query. For example, the following find all users with the name Alice:

query: {
  name: 'Alice'
}

Additionally, the following advanced criteria are supported for each property.

$in, $nin

Find all records where the property does ($in) or does not ($nin) contain the given values. For example, the following query finds every user with the name of Alice or Bob:

query: {
  name: {
    $in: ['Alice', 'Bob']
  }
}

$lt, $lte

Find all records where the value is less ($lt) or less and equal ($lte) to a given value. The following query retrieves all users 25 or younger:

query: {
  age: {
    $lte: 25
  }
}

$gt, $gte

Find all records where the value is more ($gt) or more and equal ($gte) to a given value. The following query retrieves all users older than 25:

query: {
  age: {
    $gt: 25
  }
}

$ne

Find all records that do not contain the given property value, for example anybody not age 25:

query: {
  age: {
    $ne: 25
  }
}

$or

Find all records that match any of the given objects. For example, find all users name Bob or Alice:

query: {
  $or: [
    { name: 'Alice' },
    { name: 'Bob' }
  ]
}

Changelog

0.4.0

• Migrate to new ES6 plugin infrastructure and support all advanced querying mechanisms (#10)

0.3.0

• Fixing how the module is exported.
• Adding PATCH support back in

0.2.2

• Minor bug fixes

0.2.1

• Now utilizing feathers-errors
• Proper documentation

0.2.0

• Unknown

0.1.2

• Unknown

0.1.1

• Unknown

0.1.0

• Initial release

License

Copyright (c) 2015

Licensed under the MIT license.

Changelog

v0.4.1 (2015-12-03)

Full Changelog

Merged pull requests:

• Use ES6 classes, Promises and support pagination #11 (daffl)