Populate in nodejs with type 'Schema.Types.ObjectId' return null

Question

I have a Schema that has the attributes 'paciente' and 'seguroAfiliado' with type: Schema.Types.ObjectId.

Result now:

[
    {
        "_id": "5da619b36aae5e7028fc27db",
        "paciente": "5de31abf4c430918a39a7490",
        "seguroAfiliado": "5d65da2f008b72055d17abfb",
        "fecha": "2019-10-01T03:00:00.000Z",
        "motivoConsulta": "dww",
        "__v": 0
    }
]

I need the name of those two attributes with the sentence populate in nodejs.

app.get('/', [
    mdAutenticacion.verificaToken,
], (req, res, next) => {

    var desde = req.query.desde || 0;
    desde = Number(desde);

    CitaMedica.find({})
        .skip(desde)
        .populate('paciente', ''nombre)
        .populate('seguroAfiliado', 'nombre')
        .exec(
        (err, medicalAppointment) => {

        if ( err ) {
            return res.status(500).json({
                ok: false,
                mensaje: 'Error charging list',
                errors: err
            });
        };

        CitaMedica.count({}, (err, conteo) => {
            res.status(200).json(medicalAppointment);
        });
    });
});

Try those populate but without success.

SeguroAfiliado Schema

var mongoose = require('mongoose');

var Schema = mongoose.Schema;

var seguroAfiliadoSchema = new Schema({
    nombre: {
        type: String,
        require: false
    },
    numeroPoliza: {
        type: String,
        require: false
    },
    rif: {
        type: String,
        require: false
    },
    personaContacto: {
        type: String,
        require: false
    }, 
    em: {
        type: String,
        require: false
    }, 
    telefono: {
        type: String,
        require: false
    },
    email: {
        type: String,
        require: false
    },
    status: {
        type: String,
        require: false
    },
    imgSeguroAfiliado: {
        type: String,
        require: false
    },
    pais: {
        type: String,
        require: false
    },
    baremo: {
        type: String,
        require: false
    },
    actoQuirurgico: {
        type: String,
        require: false
    },
}, { collection: 'seguroAfiliado' });

module.exports = mongoose.model( 'Seguro Afiliado', seguroAfiliadoSchema );

CitasMedicas Schema

var mongoose = require('mongoose');

var Schema = mongoose.Schema;

var citasMedicasSchema = new Schema({
    doctorId: {
        type: String,
        require: false
    },
    safeName: {
        type: String,
        require: false
    },
    paciente: {
        type: Schema.Types.ObjectId,
        require: false
    },
    seguroAfiliado: {
        type: Schema.Types.ObjectId,
        require: false
    },
    fecha: {
        type: String,
        require: false
    },
    motivoConsulta: {
        type: String,
        require: false
    },
}, { collection: 'citasMedicas' });

module.exports = mongoose.model( 'Citas Médicas', citasMedicasSchema );

The result with that attempt is:

[
    {
        "_id": "5da619b36aae5e7028fc27db",
        "paciente": null,
        "seguroAfiliado": null,
        "fecha": "2019-10-01T03:00:00.000Z",
        "motivoConsulta": "dww",
        "__v": 0
    }
]

Answer 1

You forgot the ref option what tells Mongoose which model to use during population. In your case, the CitasMedicas schema should be something like:

var citasMedicasSchema = new Schema({
  ...
  paciente: {
    type: Schema.Types.ObjectId,
    ref: "RefModel",
    require: false
  },
  seguroAfiliado: {
    type: Schema.Types.ObjectId,
    ref: "RefModel",
    require: false
  },
  ...
}...