How popular is an object loaded with populate in Mongoose?

Question

I have a doubt, if I already have a query being populated in Mongoose, and it is populated with a model that also has relationship, there is a way to popular it too?

For example:

I have my model of Os:

const mongoose = require('../config/database');
const Schema = mongoose.Schema;

const OsSchema = new Schema({

    nome: {type: String, required: true},
    cnpjcpf: {type: String, required: true},
    dataservico: { type:Date, required:true},
    datagarantia: { type:Date, required:true},
    duracao: { type:Number},
    dificuldade: {type: Number},
    vendedor: {type: String, required: true},
    score: {type: Number, required: true},
    done: {type: Boolean, required:true},
    created: { type:Date, default:Date.now()},
    operador:[{type: Schema.Types.ObjectId, ref: 'Operador'}],
    pragas:[{type: Schema.Types.ObjectId, ref: 'Praga'}],
    produtos:[{type: Schema.Types.ObjectId, ref: 'Produto'}],
    reforco:[{type: Schema.Types.ObjectId, ref: 'Reforco'}],
    
},{toJSON:{virtuals:true}});


module.exports = mongoose.model('Os', OsSchema);

But my model of reforco also has relations:

const mongoose = require('../config/database');
const Schema = mongoose.Schema;

const ReforcoShema = new Schema({

    dataservico: { type:Date, required:true},
    duracao: { type:Date},
    done: {type: Boolean, required:true},
    programado: {type: Boolean, required:true},
    operador:[{type: Schema.Types.ObjectId, ref: 'Operador'}],
    pragas:[{type: Schema.Types.ObjectId, ref: 'Praga'}],
    produtos:[{type: Schema.Types.ObjectId, ref: 'Produto'}],
    created: { type:Date, default:Date.now()}

},{toJSON:{virtuals:true}});


module.exports = mongoose.model('Reforco', ReforcoShema);

When I query Os and population the reforco, He brings back the reinforcement normally, but only brings back the ID of the relations of the reinforcement, there is a means of popular they also?

Answer 1

You would have to use populate for multiple levels. In your case you can try to pass a contentious array of field rules to popular.

An example for your case, let’s popular the field reforco and from this field we also want to popular the field operador:

Os.find({ nome: req.body.nome })     // filtro qualquer
  .populate({
    path: 'reforco',                 // populamos o "reforco"
    populate: [{ path: 'operador' }] // passamos um array com objetos
                                     // com os campos a serem populados
                                     // neste caso o campo "operador"
  })

If you want to populate more fields, pass more objects to the array:

Os.find({ nome: req.body.nome })
  .populate({
    path: 'reforco',
    populate: [{ path: 'operador' }, { path: 'pragas' }, { path: 'produtos' }]
  })

It’s called Populating Across Multiple levels and we can find in the documentation of Mongoosis.