Mongoose: Populating with projection using attribute of scheme

[lmartinez12]

I triying the following population/projection and work fine

  modelBaby.findOne({'userId': req.user.data._id, '_id': req.params.id})
  .populate('categories._categoryId', {
    levels:{
      $elemMatch:{
        name: 'PURPLE'
      }
    }
  })

But i need name as a variable something like:

modelBaby.findOne({'userId': req.user.data._id, '_id': req.params.id})
      .populate('categories._categoryId', {
        levels:{
          $elemMatch:{
            // over heree !!
            name: 'categories._levelName' or this._levelName
          }
        }
      })

the scheme ref is

const babyCategory = new mongoose.Schema(
      {
        answer: {type: String},
        _categoryId: {type: Schema.Types.ObjectId, required: true, ref: 'category'},
        _categoryName: {type: String, required: true},
        _levelName: {type: String, required: true}
      },
      {versionKey: false, _id : false}
    );

This is possible ? or how is the best way to approach this

Thanks btw =D

[sobafuchs]

For now you would have to fetch it manually and match on it. I'll label this a feature request for 4.12