How to write a Mongoose model in ES6 / ES2015

Question

I want to write my mongoose model in ES6. Basically replace module.exports and other ES5 things wherever possible. Here is what I have.

import mongoose from 'mongoose'

class Blacklist extends mongoose.Schema {
  constructor() {
    super({
      type: String,
      ip: String,
      details: String,
      reason: String
    })
  }
}

export default mongoose.model('Blacklist', Blacklist)

I see this error in the console.

if (!('pluralization' in schema.options)) schema.options.pluralization = this.options.pluralization;
                                 ^

TypeError: Cannot use 'in' operator to search for 'pluralization' in undefined

Answer 1

I'm not sure why you're attempting to use ES6 classes in this case. mongoose.Schema is a constructor to create new schemas. When you do

var Blacklist = mongoose.Schema({});

you are creating a new schema using that constructor. The constructor is designed so that behaves exactly like

var Blacklist = new mongoose.Schema({});

What you're alternative,

class Blacklist extends mongoose.Schema {

does is create a subclass of the schema class, but you never actually instantiate it anywhere

You'd need to do

export default mongoose.model('Blacklist', new Blacklist());

but I wouldn't really recommend it. There's nothing "more ES6y" about what you are doing. The previous code is perfectly reasonable and is the recommended API for Mongoose.

Answer 2

Mongoose can natively support es6 classes (since 4.7, and with no transpiler…).

Just write:

const mongoose = require('mongoose')
const { Model, Schema } = mongoose

const schema = new Schema({
  type: String,
  ip: String,
  details: String,
  reason: String,
})

class Tenant extends Model {}

module.exports = mongoose.model(Tenant, schema, 'tenant');

Answer 3

Why would you want to do it? mongoose.Schema is not expected to be used in this way. It doesn't use inheritance.

mongoose.Schema is a constructor that takes an object as the first parameter both in ES5 and ES6. No need for ES6 classes here.

Thus even with ES6 the proper way is to have:

const Blacklist = mongoose.Schema({
  type: String,
  ip: String,
  details: String,
  reason: String,
});

Answer 4

For those who find this searching around, the original question seems pretty valid to me. I'm using Babel transpiling ES6+ down to 5. My custom mongoose methods did not play well with my async/await code in my calling class. Notably this was null in my instance methods. Using the solution provided here, I was able to arrive at this solution that hopefully helps others searching around.

import mongoose from 'mongoose'

class Tenant extends mongoose.Schema {
  constructor() {
    const tenant = super({
      pg_id: Number,
      name: String,
      ...
    })

    tenant.methods.getAccountFields = this.getAccountFields
    tenant.methods.getCustomerTypes = this.getCustomerTypes
    tenant.methods.getContactFields = this.getContactFields
    ...
    tenant.methods.getModelFields = this.getModelFields

    return tenant
  }

  getAccountFields() {
    return this.getModelFields(this.account_fields_mapping)
  }

  getCustomerTypes() {
    //code
  }

  getContactFields() {
    //code
  }

  ...

  getModelFields(fields_mapping) {
    //code
  }
}

export default mongoose.model('Tenant', new Tenant)

Answer 5

To do things the ES6, class-like way, as the question states, I simply had to invoke the class with new in the exported mongoose.model function.

export default mongoose.model('Blacklist', new Blacklist)

Answer 6

This might be late to reply still, this may help someone who looking for this.

With ES6 Classes Schemas have a loadClass() method that you can use to create a Mongoose schema from an ES6 class:

• ES6 class methods become Mongoose methods
• ES6 class statics become Mongoose statics
• ES6 getters and setters become Mongoose virtuals

Here's an example of using loadClass() to create a schema from an ES6 class:

class MyClass {
  myMethod() { return 42; }
  static myStatic() { return 42; }
  get myVirtual() { return 42; }
}

const schema = new mongoose.Schema();
schema.loadClass(MyClass);

console.log(schema.methods); // { myMethod: [Function: myMethod] }
console.log(schema.statics); // { myStatic: [Function: myStatic] }
console.log(schema.virtuals); // { myVirtual: VirtualType { ... } }

Reference: this is a sample code from mongoose documentation, for more details mongoose doc

Answer 7

I'm going to give a 2022 answer and how I do it with ES6. I think that using classes is not bringing benefit while creating a schema since it is just the definition or shape of the data.

// package.json
{
  ...
  "type": "module",
}

// root/models/users.model.js
import mongoose from 'mongoose'

const userSchema = new mongoose.Schema({ ... })

const UserModel = mongoose.model('Users', userSchema)
export { UserModel }

// root/routes/users.routes.js
import express from 'express'
import { UserModel } from '../models/users.model.js'

const userRouter = express.Router()

userRouter.post('/', async (req, res) => {
  const user = UserModel.create({ ...req.body })
  ...
}

I was having trouble myself using export default and module.exports but export {... } worked as expected.

Answer 8

This will work:

import mongoose from 'mongoose';

const { Schema } = mongoose;
const userSchema = new Schema({

  email: {
      type: String,
      required: true
  },
  firstName: {
      type: String,
  },
  lastName: {
      type: String
  },
  age: {
      type: Number
  }
});

export default mongoose.model('User', userSchema);