Mongoose populate nested array

Question

Assuming the following 3 models:

var CarSchema = new Schema({
  name: {type: String},
  partIds: [{type: Schema.Types.ObjectId, ref: 'Part'}],
});

var PartSchema = new Schema({
  name: {type: String},
  otherIds: [{type: Schema.Types.ObjectId, ref: 'Other'}],
});

var OtherSchema = new Schema({
  name: {type: String}
});

When I query for Cars I can populate the parts:

Car.find().populate('partIds').exec(function(err, cars) {
  // list of cars with partIds populated
});

Is there a way in mongoose to populate the otherIds in the nested parts objects for all the cars.

Car.find().populate('partIds').exec(function(err, cars) {
  // list of cars with partIds populated
  // Try an populate nested
  Part.populate(cars, {path: 'partIds.otherIds'}, function(err, cars) {
    // This does not populate all the otherIds within each part for each car
  });
});

I can probably iterate over each car and try to populate:

Car.find().populate('partIds').exec(function(err, cars) {
  // list of cars with partIds populated

  // Iterate all cars
  cars.forEach(function(car) {
     Part.populate(car, {path: 'partIds.otherIds'}, function(err, cars) {
       // This does not populate all the otherIds within each part for each car
     });
  });
});

Problem there is that I have to use a lib like async to make the populate call for each and wait until all are done and then return.

Possible to do without looping over all cars?

Community · Accepted Answer · 2017-05-23 12:02:37Z

45

Update: Please see Trinh Hoang Nhu's answer for a more compact version that was added in Mongoose 4. Summarized below:

Car
  .find()
  .populate({
    path: 'partIds',
    model: 'Part',
    populate: {
      path: 'otherIds',
      model: 'Other'
    }
  })

Mongoose 3 and below:

Car
  .find()
  .populate('partIds')
  .exec(function(err, docs) {
    if(err) return callback(err);
    Car.populate(docs, {
      path: 'partIds.otherIds',
      model: 'Other'
    },
    function(err, cars) {
      if(err) return callback(err);
      console.log(cars); // This object should now be populated accordingly.
    });
  });

For nested populations like this, you have to tell mongoose the Schema you want to populate from.

edited May 23, 2017 at 12:02

CommunityBot

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answered Jan 27, 2015 at 21:33

Sven

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6 Comments

lostintranslation Over a year ago

Crap RTFM ;) I see that now. However no matter what I try I get back an empty array for otherIds. As a sanity check If I don't call the populate method there is an array of id's (which is correct). Populate is not populating those ids. Running 3.8.22 lastest from npm

lostintranslation Over a year ago

Also have logging turned on. I do not see another call to the other collection to populate the 'join'. So mongoose isn't even making the call.

JohnnyHK Over a year ago

@lostintranslation It should be model: 'Other' in that nested populate call.

lostintranslation Over a year ago

@JohnnyHK to the rescue again, thanks! As a side note I though I might be able to get it all the first call Car.find().populate('partIds').populate({path: 'partIds.otherIds', model: 'Other').exec ... No luck guess you have to make the first query call to populate the partIds first.

Buu Over a year ago

Or, you can try the mongoose-deep-populate plugin and rewrite the entire thing with: Car.find().deepPopulate('partIds.otherIds').exec(...). (Disclaimer: I'm the author.)

|

Nhu Trinh · Accepted Answer · 2015-12-23 22:32:16Z

29

Mongoose 4 support this

Car
.find()
.populate({
  path: 'partIds',
  model: 'Part',
  populate: {
    path: 'otherIds',
    model: 'Other'
  }
})

answered Dec 23, 2015 at 22:32

Nhu Trinh

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2 Comments

Harshad Ranganathan Over a year ago

Note: model: 'Other' is necessary. Without it, it gives empty array. Docs doesn't specify it : mongoosejs.com/docs/populate.html#deep-populate

Shivam Verma Over a year ago

But I want to do double populate in one nested level. So basically something like below, Car .find() .populate({ path: 'partIds', model: 'Part', populate: { path: 'otherIds', model: 'Other' } populate: { path: 'ModelIds', model: 'Model' } })

joeytwiddle · Accepted Answer · 2016-01-26 14:23:53Z

4

Use mongoose deepPopulate plugin

car.find().deepPopulate('partIds.otherIds').exec();

edited Jan 26, 2016 at 14:23

joeytwiddle

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answered Jul 30, 2015 at 9:38

Riyas TK

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Comments

Tuấn Anh Đào · Accepted Answer · 2019-07-31 04:40:43Z

0

It's should be better with

Car
.find()
.populate({
    path: 'partIds.othersId'
})

answered Jul 31, 2019 at 4:40

Tuấn Anh Đào

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