Mongoose .Populate() returns empty array

Question

I do not understand what the problem is. And why each element from the 'tasks' array is null.

Schema = mongoose.Schema;

const userSchema = new Schema({
    email: {
    type: String,
    required: true 
},  
password: {
    type: String,
    required: true 
},
tasks: [{type: Schema.Types.ObjectId, ref: 'Task'}]
}
);

const taskSchema = new Schema({
title: String
});

const User = mongoose.model('User', userSchema);
const Task = mongoose.model('Task', taskSchema);

// Add some default to DB
const task1 = new Task({
title: "Welcome! Here You Can:"
});

const task2 = new Task({
title: "ADD EDIT DELETE SHARE your TASKS "
});

const defaultTasks = [task1, task2];

When create new User I Add defaultTasks

const newUser = {
    email: req.body.email,
    password: req.body.password,
    tasks: defaultTasks
};

Get Users Tasks

app.get('/tasks/', function(req, res){
const email = req.query.user;  
User
    .findOne({email: email})
    .populate('tasks')
    .exec()
    .then(foundUser => {

        console.log(foundUser);
        const data = [];
        Object.keys(foundUser.tasks).forEach(function(key) {
        const val = foundUser.tasks[key];
        data.push([val.title, val._id]);
    });
    res.send(data);
    console.log('Data to send ' + data);        

});
});

Before .Populate() console.log {

{ tasks: [ 5cf78ac1d08ee617fc89f7ed, 5cf78ac1d08ee617fc89f7ee ]

After { { tasks: [],

Please Help! All that I found did not solve my problem. Maybe problem in defaultTasks. But i dont see it.

Answer 1

Your code doesn't save your task to DB, it just creates an object. So later when you populate User there are no tasks in DB to be found.

 const task1 = await new Task({ title: "Welcome! Here You Can:" }).save(); // or const task1 = await Task.create({ title: "Welcome! Here You Can:" }); 

Ps of course you can deal with asynchronous calls the way you want.