Implements schema inheritance and an optional discriminator key which is useful for storing different types of related documents in a collection and fetching them with the correct model type.
Install via NPM
$ npm install mongoose-schema-extend
You just require the library to add schema extend method
var mongoose = require('mongoose'), extend = require('mongoose-schema-extend'); var Schema = mongoose.Schema; var PersonSchema = new Schema({ name : String }, { collection : 'users' }); var EmployeeSchema = PersonSchema.extend({ department : String }); var Person = mongoose.model('Person', PersonSchema), Employee = mongoose.model('Employee', EmployeeSchema); var Brian = new Employee({ name : 'Brian Kirchoff', department : 'Engineering' }); ...
By adding the discriminatorKey schema option, a key is added to your saved documents with the model name and is used when finding documents of different types to set them to the correct model
... var VehicleSchema = mongoose.Schema({ make : String, }, { collection : 'vehicles', discriminatorKey : '_type' }); var CarSchema = VehicleSchema.extend({ year : Number }); var BusSchema = VehicleSchema.extend({ route : Number }) var Vehicle = mongoose.model('vehicle', VehicleSchema), Car = mongoose.model('car', CarSchema), Bus = mongoose.model('bus', BusSchema); var accord = new Car({ make : 'Honda', year : 1999 }); var muni = new Bus({ make : 'Neoplan', route : 33 }); accord.save(function(err) { muni.save(function(err) { // vehicles are saved with the _type key set to 'car' and 'bus' }); })
At this point in MongoDB you will have documents similar to this
{ "_type" : "car", "make" : "Honda", "year" : 1999, "_id" : ObjectId("5024460368368a3007000002"), "__v" : 0 }
{ "_type" : "bus", "make" : "Neoplan", "route" : 33, "_id" : ObjectId("5024460368368a3007000003"), "__v" : 0 }
When querying, the objects model prototype will be set based on the _type field, so they are fully functional
Vehicle.find({}, function(err, vehicles) { console.log(vehicles[0]); // vehicles[0] instanceof Car === true console.log(vehicles[1]); // vehicles[1] instanceof Bus === true });
To run the tests install mocha
npm install mocha -g
and then run
mocha