microgen-mongoose

A Feathers database adapter for Mongoose, an object modeling tool for MongoDB.

$ npm install --save mongoose microgen-mongoose

Important: microgen-mongoose implements the Feathers Common database adapter API and querying syntax.

This adapter also requires a running MongoDB database server.

API

service(options)

Returns a new service instance initialized with the given options. Model has to be a Mongoose model. See the Mongoose Guide for more information on defining your model.

const mongoose = require('mongoose');
const service = require('microgen-mongoose');

// A module that exports your Mongoose model
const Model = require('./models/message');

// Make Mongoose use the ES6 promise
mongoose.Promise = global.Promise;

// Connect to a local database called `feathers`
mongoose.connect('mongodb://localhost:27017/feathers');

app.use('/messages', service({ Model }));
app.use('/messages', service({ Model, lean, id, events, paginate }));

Options:

• Model (required) - The Mongoose model definition
• lean (optional, default: true) - Runs queries faster by returning plain objects instead of Mongoose models.
• id (optional, default: '_id') - The name of the id field property.
• events (optional) - A list of custom service events sent by this service
• paginate (optional) - A pagination object containing a default and max page size
• whitelist (optional) - A list of additional query parameters to allow (e..g [ '$regex', '$populate' ])
• multi (optional) - Allow create with arrays and update and remove with id null to change multiple items. Can be true for all methods or an array of allowed methods (e.g. [ 'remove', 'create' ])
• overwrite (optional, default: true) - Overwrite the document when update, making mongoose detect is new document and trigger default value for unspecified properties in mongoose schema.
• discriminators (optional) - A list of mongoose models that inherit from Model.
• useEstimatedDocumentCount (optional, default: false) - Use estimatedDocumentCount instead (usuall not necessary)

Important: To avoid odd error handling behaviour, always set mongoose.Promise = global.Promise. If not available already, Feathers comes with a polyfill for native Promises.

Important: When setting lean to false, Mongoose models will be returned which can not be modified unless they are converted to a regular JavaScript object via toObject.

Note: You can get access to the Mongoose model via this.Model inside a hook and use it as usual. See the Mongoose Guide for more information on defining your model.

params.mongoose

When making a service method call, params can contain a mongoose property which allows you to modify the options used to run the Mongoose query. Normally, this will be set in a before hook:

app.service('messages').hooks({
  before: {
    patch(context) {
      // Set some additional Mongoose options
      // The adapter tries to use these settings by defaults
      // but they can always be changed here
      context.params.mongoose = {
        runValidators: true,
        setDefaultsOnInsert: true
      }
    }
  }
});

The mongoose property is also useful for performing upserts on a patch request. "Upserts" do an update if a matching record is found, or insert a record if there's no existing match. The following example will create a document that matches the data, or if there's already a record that matches the params.query, that record will be updated.

Using the writeResult mongoose option will return the write result of a patch operation, including the _ids of all upserted or modified documents. This can be helpful alongside the upsert flag, for detecting whether the outcome was a find or insert operation. More on write results is available in the Mongo documentation

const data = { address: '123', identifier: 'my-identifier' }
const params = {
  query: { address: '123' },
  mongoose: { upsert: true, writeResult: true }
}
app.service('address-meta').patch(null, data, params)

Example

Here's a complete example of a Feathers server with a messages Mongoose service.

$ npm install @feathersjs/feathers @feathersjs/errors @feathersjs/express @feathersjs/socketio mongoose microgen-mongoose

In message-model.js:

const mongoose = require('mongoose');

const Schema = mongoose.Schema;
const MessageSchema = new Schema({
  text: {
    type: String,
    required: true
  }
});
const Model = mongoose.model('Message', MessageSchema);

module.exports = Model;

Then in app.js:

const feathers = require('@feathersjs/feathers');
const express = require('@feathersjs/express');
const socketio = require('@feathersjs/socketio');

const mongoose = require('mongoose');
const service = require('microgen-mongoose');

const Model = require('./message-model');

mongoose.Promise = global.Promise;

// Connect to your MongoDB instance(s)
mongoose.connect('mongodb://localhost:27017/feathers');

// Create an Express compatible Feathers application instance.
const app = express(feathers());

// Turn on JSON parser for REST services
app.use(express.json());
// Turn on URL-encoded parser for REST services
app.use(express.urlencoded({extended: true}));
// Enable REST services
app.configure(express.rest());
// Enable Socket.io services
app.configure(socketio());
// Connect to the db, create and register a Feathers service.
app.use('/messages', service({
  Model,
  lean: true, // set to false if you want Mongoose documents returned
  paginate: {
    default: 2,
    max: 4
  }
}));
app.use(express.errorHandler());

// Create a dummy Message
app.service('messages').create({
  text: 'Message created on server'
}).then(function(message) {
  console.log('Created message', message);
});

// Start the server.
const port = 3030;
app.listen(port, () => {
    console.log(`Feathers server listening on port ${port}`);
});

You can run this example by using node app and go to localhost:3030/messages.

Querying, Validation

Mongoose by default gives you the ability to add validations at the model level. Using an error handler like the one that comes with Feathers your validation errors will be formatted nicely right out of the box!

For more information on querying and validation refer to the Mongoose documentation.

$populate

For Mongoose, the special $populate query parameter can be used to allow Mongoose query population.

Important: $populate has to be whitelisted explicitly since it can expose protected fields in sub-documents (like the user password) which have to be removed manually.

const mongoose = require('microgen-mongoose');

app.use('/posts', mongoose({
  Model,
  whitelist: [ '$populate' ]
});

app.service('posts').find({
  query: { $populate: 'user' }
});

Error handling

As of v7.3.0, the original Mongoose error can be retrieved on the server via:

const { ERROR } = require('microgen-mongoose');

try {
  await app.service('posts').create({ value: 'invalid' });
} catch(error) {
  // error is a FeathersError
  // Safely retrieve the original Mongoose error
  const mongooseError = error[ERROR];
}

Discriminators (Inheritance)

Instead of strict inheritance, Mongoose uses discriminators as their schema inheritance model. To use them, pass in a discriminatorKey option to your schema object and use Model.discriminator('modelName', schema) instead of mongoose.model()

Feathers comes with full support for mongoose discriminators, allowing for automatic fetching of inherited types. A typical use case might look like:

var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var Post = require('./post');
var feathers = require('@feathersjs/feathers');
var app = feathers();
var service = require('microgen-mongoose');

// Discriminator key, we'll use this later to refer to all text posts
var options = {
  discriminatorKey: '_type'
};

var TextPostSchema = new Schema({
  text: { type: String, default: null }
}, options);

// Note the use of `Post.discriminator` rather than `mongoose.discriminator`.
var TextPost = Post.discriminator('text', TextPostSchema);

// Using the discriminators option, let feathers know about any inherited models you may have
// for that service
app.use('/posts', service({
  Model: Post,
  discriminators: [TextPost]
}))

Without support for discriminators, when you perform a .get on the posts service, you'd only get back Post models, not TextPost models. Now in your query, you can specify a value for your discriminatorKey:

{
  _type: 'text'
}

and Feathers will automatically swap in the correct model and execute the query it instead of its parent model.

Collation Support

This adapter includes support for collation and case insensitive indexes available in MongoDB v3.4. Collation parameters may be passed using the special collation parameter to the find(), remove() and patch() methods.

Example: Patch records with case-insensitive alphabetical ordering

The example below would patch all student records with grades of 'c' or 'C' and above (a natural language ordering). Without collations this would not be as simple, since the comparison { $gt: 'c' } would not include uppercase grades of 'C' because the code point of 'C' is less than that of 'c'.

const patch = { shouldStudyMore: true };
const query = { grade: { $gte: 'c' } };
const collation = { locale: 'en', strength: 1 };
students.patch(null, patch, { query, collation }).then( ... );

Example: Find records with a case-insensitive search

Similar to the above example, this would find students with a grade of 'c' or greater, in a case-insensitive manner.

const query = { grade: { $gte: 'c' } };
const collation = { locale: 'en', strength: 1 };
students.find({ query, collation }).then( ... );

For more information on MongoDB's collation feature, visit the collation reference page.

Mongo-DB Transaction

This adapter includes support to enable database transaction to rollback the persisted records for any error occured for a api call. This requires Mongo-DB v4.x installed and replica-set enabled.

Start working with transaction enabled by adding the following lines in app.hooks.js or <any-service>.hooks.js.

const TransactionManager = require('microgen-mongoose').TransactionManager;
const isTransactionEnable = process.env.TRANSACTION_ENABLE || false;
const skipPath = ['login'];

let moduleExports = {
  before: {
    all: [],
    find: [],
    get: [],
    create: [
      when(isTransactionEnable, async hook =>
        TransactionManager.beginTransaction(hook, skipPath)
      )
    ],
    update: [
      when(isTransactionEnable, async hook =>
        TransactionManager.beginTransaction(hook, skipPath)
      )
    ],
    patch: [],
    remove: []
  },

  after: {
    all: [],
    find: [],
    get: [],
    create: [when(isTransactionEnable, TransactionManager.commitTransaction)],
    update: [when(isTransactionEnable, TransactionManager.commitTransaction)],
    patch: [],
    remove: []
  },

  error: {
    all: [],
    find: [],
    get: [],
    create: [when(isTransactionEnable, TransactionManager.rollbackTransaction)],
    update: [when(isTransactionEnable, TransactionManager.rollbackTransaction)],
    patch: [],
    remove: []
  }
};

module.exports = moduleExports;

Contributing

This module is community maintained and open for pull requests. Features and bug fixes should contain

• The bug fix / feature code
• Tests to reproduce the bug or test the feature
• Documentation updates (if necessary)

To contribute, fork and clone the repository. To run the tests, a MongoDB v4.0.0 server is required. If you do not have a MongoDB server running you can start one with:

npm run mongodb

The command needs to stay open while running the tests with

npm test

License

MIT

Authors

• Feathers contributors