Mongo db, how to give object _id another collection's document - node.js

Question

I have 2 collections called User and Location. In User, there is a location _id and this is an Object. Id also references the location collection. My question is what did I do wrong? When I call getUser function I want to see user information and the user's location information. What I need to do ?
User Schema
module.exports = (function userSchema() {
var Mongoose = require('mongoose');
var userSchema = Mongoose.Schema({
name: {
type: String,
require: true
},
surname: {
type: String,
require: true
},
tel: {
type: String,
require: true
},
age: {
type: String,
require: true
},
mevki_id: {
type: String,
require: true
},
location_id: [{
type: Mongoose.Schema.Types.ObjectId,
ref: 'locations'
}]
});
var collectionName = 'users';
var User = Mongoose.model(collectionName, userSchema);
return User;
})();
User Controller
function userController() {
var User = require('../models/UserSchema');
this.createUser = function (req, res, next) {
var name = req.body.name;
var surname = req.body.surname;
var tel = req.body.tel;
var age = req.body.age;
var mevki_id = req.body.mevki_id;
var lok_id = req.body.lok_id;
User.create({
name: name,
surname: surname,
tel: tel,
age: age,
mevki_id: mevki_id,
lok_id: lok_id
}, function (err, result) {
if (err) {
console.log(err);
return res.send({
'error': err
});
} else {
return res.send({
'result': result,
'status': 'successfully saved'
});
}
});
};
this.getUser = function (req, res, next) {
User.find()
.populate('lok_id')
.exec(function (err, result) {
if (err) {
console.log(err);
return res.send({
'error': err
});
} else {
return res.send({
'USERS': result
});
}
});
};
return this;
};
module.exports = new UserController();

Answer 1

First, your schema is wrong:
var userSchema = new Mongoose.Schema({
// ...
location_id: { type: [Mongoose.Schema.Types.ObjectId], ref: 'locations' }
})
Second, in your schema the last field name is location_id while in your controller, you change it to lok_id.
So, fix this:
User.create({
// ...
location_id: lok_id
}
and this:
User
.find()
.populate('location_id')
UPDATE
In your json the last field name is location_id, therefore, fix this too:
this.createUser = function (req, res, next) {
// ...
var lok_id = req.body.location_id;
}