Unable to populate subdocument's virtual array with dynamic ref

[yeegr]

Can I populate a dynamically referenced (with "refPath") virtual field in a subdocument array in Mongoose?

The data structure goes like

Group
 - Members -> User

Code: models/schema

let MemberSchema = new Schema({
  userId: {
    type: Schema.Types.ObjectId,
    refPath: 'userRef',
    required: true
  },
  userRef: {
    type: String,
    required: true,
    enum: ['Admin', 'User'],
    default: 'Admin'
  },
  isCreator: {
    type: Boolean,
    required: true,
    default: false
  },
  isManager: {
    type: Boolean,
    required: true,
    default: false
  },
  alias: {
    type: String,
    required: true
  },
  joined: {
    type: Number,
    required: true,
    default: UTIL.getTimestamp()
  }
}, {
  toObject: {
    virtuals: true
  },
  toJSON: {
    virtuals: true
  }
})

MemberSchema.virtual('user', {
  ref: (doc) => doc.userRef,
  localField: 'userId',
  foreignField: '_id',
  justOne: true
})

let GroupSchema = new Schema({
  title: {
    type: String,
    required: true
  },
  slug: {
    type: String,
    required: true,
    default: randomstring.generate({
      length: CONFIG.GROUP_NAME_LENGTH,
      charset: CONFIG.GROUP_NAME_CHARSET
    })
  },
  updated: {
    type: Number,
    required: true,
    default: UTIL.getTimestamp()
  },
  members: [MemberSchema]
}, {
  toObject: {
    virtuals: true
  },
  toJSON: {
    virtuals: true
  }
})

export default model('Group', GroupSchema)

Code: controller

export function get(req, res) {
  GroupModel
  .findOne({
    slug: req.params.slug
  })
  .populate({
    path: 'members.user'
  })
  .exec()
  .then((data) => {
    if (data) {
      res.status(200).json(data)        
    } else {
      res.status(404).send()
    }
  })
  .catch((err) => {
    res.status(res.statusCode).send()
    console.log(err)
  })
}

I will get a populated user if I add {model: 'Admin'} to the populate options, but that completely defeats the purpose.

[VictorGaiva]

I'm having the same issue. The execution throws TypeError: Cannot read property '0' of undefined . If I change my model's refPath to a static reference, the same populate script works as intended. Here it is the trace for the exepction:

TypeError: Cannot read property '0' of undefined
    at markArraySubdocsPopulated (/home/victor/Dev/MyProject/node_modules/mongoose/lib/document.js:555:48)
    at model.Document.$__init (/home/victor/Dev/MyProject/node_modules/mongoose/lib/document.js:515:3)
    at model.syncWrapper [as $__init] (/home/victor/Dev/MyProject/node_modules/kareem/index.js:234:23)
    at model.Document.init (/home/victor/Dev/MyProject/node_modules/mongoose/lib/document.js:481:8)
    at completeOne (/home/victor/Dev/MyProject/node_modules/mongoose/lib/query.js:2828:12)
    at /home/victor/Dev/MyProject/node_modules/mongoose/lib/query.js:2083:7
    at /home/victor/Dev/MyProject/node_modules/mongoose/lib/model.js:4598:16
    at /home/victor/Dev/MyProject/node_modules/mongoose/lib/utils.js:264:16
    at next (/home/victor/Dev/MyProject/node_modules/mongoose/lib/model.js:4071:5)
    at populate (/home/victor/Dev/MyProject/node_modules/mongoose/lib/model.js:4179:12)
    at _populate (/home/victor/Dev/MyProject/node_modules/mongoose/lib/model.js:4061:5)
    at /home/victor/Dev/MyProject/node_modules/mongoose/lib/model.js:4036:5
    at Object.promiseOrCallback (/home/victor/Dev/MyProject/node_modules/mongoose/lib/utils.js:249:12)
    at Function.Model.populate (/home/victor/Dev/MyProject/node_modules/mongoose/lib/model.js:4035:16)
    at model.Query.Query._completeOne (/home/victor/Dev/MyProject/node_modules/mongoose/lib/query.js:2077:9)
    at Immediate.<anonymous> (/home/victor/Dev/MyProject/node_modules/mongoose/lib/query.js:2116:10)

On function markArraySubdocsPopulated(doc, populated), populated is running the following data:

[
  PopulateOptions {
    _docs: {},
    path: 'supportChat.emiterId',
    _queryProjection: {}
  }
]

[VictorGaiva]

On query.js line 2052:

Query.prototype._completeOne = function(doc, res, callback) {
  if (!doc && !this.options.rawResult) {
    return callback(null, null);
  }

  const model = this.model;
  const projection = utils.clone(this._fields);
  const userProvidedFields = this._userProvidedFields || {};
  // `populate`, `lean`
  const mongooseOptions = this._mongooseOptions;
  // `rawResult`
  const options = this.options;

  if (options.explain) {
    return callback(null, doc);
  }

  if (!mongooseOptions.populate) {
    return mongooseOptions.lean ?
      _completeOneLean(doc, res, options, callback) :
      completeOne(model, doc, res, options, projection, userProvidedFields,
        null, callback);
  }
  console.log(this._mongooseOptions);
  const pop = helpers.preparePopulationOptionsMQ(this, this._mongooseOptions);
  console.log(this._mongooseOptions);
  console.log(pop);
  model.populate(doc, pop, (err, doc) => {
    if (err) {
      return callback(err);
    }
    console.log(this._mongooseOptions);
    console.log(pop);
    
    return mongooseOptions.lean ?
      _completeOneLean(doc, res, options, callback) :
      completeOne(model, doc, res, options, projection, userProvidedFields,
        pop, callback);
  });
};

gives the following data on a successful run:

{
  populate: {
    'supportChat.emiterId': PopulateOptions { _docs: {}, path: 'supportChat.emiterId' }
  }
}
{
  populate: {
    'supportChat.emiterId': PopulateOptions {
      _docs: {},
      path: 'supportChat.emiterId',
      _queryProjection: {}
    }
  }
}
[
  PopulateOptions {
    _docs: {},
    path: 'supportChat.emiterId',
    _queryProjection: {}
  }
]
{
  populate: {
    'supportChat.emiterId': PopulateOptions {
      _docs: [Object],
      path: 'supportChat.emiterId',
      _queryProjection: {},
      isVirtual: false,
      virtual: null,
      [Symbol(mongoose.PopulateOptions#Model)]: Model { Client }
    }
  }
}
[
  PopulateOptions {
    _docs: { '5db2fb1193e1ed2878b97291': [Array] },
    path: 'supportChat.emiterId',
    _queryProjection: {},
    isVirtual: false,
    virtual: null,
    [Symbol(mongoose.PopulateOptions#Model)]: Model { Client }
  }
]

and the following on a failed one:

{
  populate: {
    'supportChat.emiterId': PopulateOptions { _docs: {}, path: 'supportChat.emiterId' }
  }
}
{
  populate: {
    'supportChat.emiterId': PopulateOptions {
      _docs: {},
      path: 'supportChat.emiterId',
      _queryProjection: {}
    }
  }
}
[
  PopulateOptions {
    _docs: {},
    path: 'supportChat.emiterId',
    _queryProjection: {}
  }
]
{
  populate: {
    'supportChat.emiterId': PopulateOptions {
      _docs: {},
      path: 'supportChat.emiterId',
      _queryProjection: {}
    }
  }
}
[
  PopulateOptions {
    _docs: {},
    path: 'supportChat.emiterId',
    _queryProjection: {}
  }
]

I'm not able to understand how the last two ones have different values on the successful one when being used inside the callback.

[VictorGaiva]

On model.js line 4091, const modelsMap = getModelsMapForPopulate(model, docs, options); has an empty list when the crash happens, but has the following when it doesn't:

[
  {
    model: Model { Client },
    options: {
      model: Model { Client },
      _docs: [Object],
      path: 'supportChat.emiterId',
      _queryProjection: {},
      isVirtual: false,
      virtual: null
    },
    match: null,
    docs: [ [Object] ],
    ids: [ [Array] ],
    allIds: [ [Array] ],
    localField: Set { 'supportChat.emiterId' },
    foreignField: Set { '_id' },
    justOne: true,
    isVirtual: false,
    virtual: null,
    count: false,
    [Symbol(mongoose.PopulateOptions#Model)]: Model { Client }
  }
]

I'm pretty sure the bug can be isolated to mongoose/lib/helpers/populate/getModelsMapForPopulate.js.

[VictorGaiva]

The issue seems to be here:

mongoose/lib/helpers/populate/getModelsMapForPopulate.js

Line 272 in 7dbf96c

const normalizedRefPath = normalizeRefPath(refPath, doc, options.path);

Given the following data:

normalizeRefPath(
  "emiterType",
  {
    _id: "5db2fb1193e1ed2878b97291",
    activeAgents: [],
    isActive: true,
    hasAgent: false,
    creationTimeStamp: "2019-10-25T13:29:41.344Z",
    clientRef: "5daf1403d5412851d02be2dc",
    supportChat: [
      {
        _id: "5db2fb1193e1ed2878b97290",
        data: 'Teste',
        emiterId: "5daf1403d5412851d02be2dc",
        emiterType: 'Client',
        originalMessage: "5db2fb1193e1ed2878b9728e'
      }
    ],
    __v: 1
  },
  "supportChat.emiterId"
);

it should've returned ['supportChat', 'emiterType'] but it returns 'emiterType' instead.

[VictorGaiva]

Oh I see now. When there are nested schemes and the child scheme has a refPath, it transverses the document starting at the parent. So refPath should contain the full path to do so, but it doesn't by default.

A temporary workaround is to set the full path on child's refPath. Like this:

emiterId: { type: Schema.Types.ObjectId, refPath: 'supportChat.emiterType', required: true }

This issue should be fixed as soon as possible since the child document doesn't always knows how it is contained inside its parent component.

[vkarpov15]

@yeegr yes you should be able to do this:

MemberSchema.virtual('user', {
  ref: (doc) => doc.userRef,
  localField: 'userId',
  foreignField: '_id',
  justOne: true
})

@VictorGaiva glad you found your issue. You could also just do ref: doc => doc.emiterType