Populating nested array with ObjectIDs

Question

Trying to populate an array of ObjectID's within my schema. I've looked around at similar answers but it seems everyone is doing it slightly differently and I haven't been able to find a solution myself.

My schema looks like this:

var GameSchema = new Schema({
  title: String,
  description: String,
  location: String,
  created_on: { type: Date, default: Date.now },
  active: { type: Boolean, default: true },
  accepting_players: { type: Boolean, default: true },
  players: [{
    type: Schema.Types.ObjectId,
    ref: 'User'
  }],
  admins: [{
    type: Schema.Types.ObjectId,
    ref: 'User'
  }]
});

So far I've been trying to populate it like this, which obviously isn't working

exports.getAdmins = function(req, res) {
  Game.findById(req.params.id)
  .populate('admins')
  .exec(function(err, game) {
    return res.json(200, game.admins);
  });
};

I hate to add to the list of population questions, but I've looked at many and haven't found a solution. Any help is greatly appreciated!

Edit: Here's how I am adding admins to the document

// Add admin to game
exports.addAdmin = function(req, res) {
  Game.findByIdAndUpdate(
    req.params.id,
    { $push: { 'admins': req.params.user_id }},
    function(err, game) {
      if(err) { return handleError(res, err); }
      if(!game) { return res.send(404); }
      return res.json(200, game.admins);
    });
};

can you give an example of how you are saving your game objects, this should work, just attempted the same structure on my end in a test app and it worked fine. — Mattias Farnemyhr, Sep 11 '14 at 20:40
@materik Edited the code for how I add admins to the game. When I get the game document from the API all the data is correct and I can see the admin ID's saved in the array. Let me know if I answered your question. — jket, Sep 12 '14 at 01:30
Hmm.. yes, that looks good. What version of mongodb are you running. I don't know if that makes a difference but I remember I had a problem with populate before I upgraded version. — Mattias Farnemyhr, Sep 12 '14 at 07:57
@materik I was on version 2.6.0 so I brew upgraded to 2.6.4 but that didn't fix the problem at first. However I looked through some more mongoose documentation and got it working, I'll post the solution I found in the answer. Thanks for the help! — jket, Sep 12 '14 at 16:45

score 0 · Accepted Answer · answered Sep 12 '14 at 17:57

Well I went back to mongoose documentation, and decided to change how I looked up a game by an ID and then populated the response.

Now my working function looks like this:

// Returns admins in a game
exports.getAdmins = function(req, res) {
  Game.findById(req.params.id, function(err, game) {
    if(err) { return handleError(res, err); }
    if(!game) { return res.send(404); }
    Game.populate(game, { path: 'admins' }, function(err, game) {
      return res.json(200, game);
    });
  });
};

The issue I was having was that I was trying to call the .populate function directly with the .findById method, but that doesn't work because I found on mongoose's documentation the the populate method need the callback function to work, so I just added that and voila, it returned my User object.

slim · Answer 2 · 2015-04-29T15:50:33.797

0

to populate an array, you just have to put model name field after path field like this :

 Game.findById(req.params.id)
         .populate({path: 'admins', model: 'AdminsModel'})
         .exec(function(err, game){...});

it works perfectly on my projects...

edited Apr 29 '15 at 15:50

answered Dec 21 '14 at 09:38

slim

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Populating nested array with ObjectIDs

2 Answers2