CODEWITHSUNDEEP
node.jsmongodbexpressmongoose
Ronald Langeveld
Ronald Langeveld

Reputation: 744

Mongoose / Mongodb - should I explicitly add objectid to populate?

So I have 2 models, one is users and the other is sessions.

It was initially setup as: 

const users = mongoose.Schema({
    _id: mongoose.Schema.Types.ObjectId,
    username: {type: String, unique: true},
}
);
module.exports = mongoose.model('User', users,);

I then went on and added another model, called sessions, 

const sessions = mongoose.Schema({
    _id: {type: mongoose.Schema.Types.ObjectId, default: mongoose.Schema.Types.ObjectId, null: false},
    user_id: {type: mongoose.Schema.Types.ObjectId, ref: 'User'},
    timestamp: {type: Date},
});

module.exports = mongoose.model('Sessions', sessions);

I then decided, I want to to be able to pull the user's sessions along with the users and added sessions: [{type: mongoose.Schema.Types.ObjectId, ref: 'SurfSessions', default: null}] to my users model schema.

I quickly learnt that users.findOne(username:admin).populate('sessions') isn't gonna fill up sessions by itself, as sessions returns as an empty array [].

Since I don't have sessions inside users populated with objectid's does that mean I cannot populate sessions or is there another way?

Upvotes: 0

Views: 396

Answers (1)

Fibo36
Fibo36

Reputation: 84

You should be able to do this with virtual populate:

const users = new mongoose.Schema(
  {
    _id: mongoose.Schema.Types.ObjectId,
    username: { type: String, unique: true },
  },
  { toJSON: { virtuals: true }, toObject: { virtuals: true } }
);
module.exports = mongoose.model('User', users);

Then: 

userSchema.virtual('sessions', {
  ref: 'Session', // model to search in
  foreignField: 'user_id', 
  localField: '_id', // checks where user_id on session === _id on user
});

After this, use .populate('sessions') as normal. For more check this out: https://mongoosejs.com/docs/tutorials/virtuals.html#populate

Upvotes: 1

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