Mongoose schema inheritance example

mongoose-schema-inheritance.js

"use strict";

var mongoose = require('mongoose'),
    Schema = mongoose.Schema;


// ==== connect to database ====
mongoose.connect('mongodb://localhost/temp');


// ==== base object to be inherited ====
var baseObj = {
	a : Number,
	b : String
};


// ==== inherit objects as needed at runtime ====

// inherited objects
var objA = Object.create(baseObj);
objA.c = [Number];

var objB = Object.create(baseObj);
objB.c = String;

// create schema and model
var SchemaA = new Schema(objA),
    modelA = mongoose.model('modelA', SchemaA, 'collectionAB');

var SchemaB = new Schema(objB),
    modelB = mongoose.model('modelB', SchemaB, 'collectionAB');

// save a record
var recordA = new modelA({
	  a : 1
	, b : 'a'
	, c : [1,2,3]
});

var recordB = new modelB({
	  a : 2
	, b : 'z'
	, c : 'c'
});

recordA.save();
recordB.save();

// ==== output from mongo console ====

/* > db.collectionAB.find()
	{ "a" : 1, "b" : "a", "_id" : ObjectId("501727f26a5ec8e189000001"), "c" : [ 1, 2, 3 ] }
	{ "a" : 2, "b" : "z", "c" : "c", "_id" : ObjectId("501727f26a5ec8e189000002") }
*/

This still works in 2018, mongoose 5.0.12 Use only object.assign() instead of Object.create().

const baseObj:any = {
a :{ type: Number, required: false},
b : { type: String, required: false }
};

// inherited objects
const objA:any = Object.assign(baseObj);
objA.extra = {
value: { type: String, required: false }
}

const schema:Schema = new Schema( objA );
export mongoose.model('ModelA', schema, 'collection');

`

Very helpful