Mongoose: deep population (populate a populated field)

Question

I have Category model:

Category:
    ...
    articles: [{type:ObjectId, ref:\'Article\'}]

Article model contains ref to

Answer 1

If you want select multi populate inside populate, you should try this way:

I have Booking schema:

let Booking = new Schema({
  ...,  // others field of collection
  experience: { type: Schema.Types.ObjectId, ref: 'Experience' },
  ...},{
    collection: 'booking'
  });

and Experience schema:

let Experience = new Schema({
  ...,
  experienceType: {type: Schema.Types.ObjectId, ref: 'ExperienceType'},
  location: {type: Schema.Types.ObjectId, ref: 'Location'},
  ...} // others field of collection
  ,{
    collection: 'experience'
  });

get ExperienceType and Location of Experience when you find Booking:

Booking.findOne({_id: req.params.id})
  .populate({path: 'experience',
    populate: [{path: 'experienceType', select: 'name'}, {path: 'location', select: 'name'}],
  })
  .exec((err, booking) => {
    if(err){
      console.log(err);
    }
    else {
      res.json(booking);
    }
  });