Mongoose | Keep the same Population to all functions

Question

I Have this schema for my Crop Model

var CropSchema = new mongoose.Schema({
    name: String,
    zones: [{
        type: Schema.Types.ObjectId,
        ref: 'zone'
    }],
    ...
});

This schema for my Zone Model

var ZoneSchema = new mongoose.Schema({
    name: String,
    poor: [{
        type: Schema.Types.ObjectId,
        ref: 'condition'
    }],
    ...
});

This schema for my Condition Model

var ConditionSchema = new mongoose.Schema({
    name: String,
    action_on_controls: [{
        type: Schema.Types.ObjectId,
        ref: 'control'
    }],
    ...
});

And this schema for my Control Model

var ControlSchema = new mongoose.Schema({
    name: String,
    ...
});

The way I am getting all the Crops in Node is this:

  public index(req: Request, res: Response) {
    return Crop.find().populate('zones').populate({
      path: 'zones',
      populate: [
        {
          path: 'poor', populate: [
            { path: 'action_on_controls' }]
        }
      ]
    }).exec()
      .then(respondWithResult(res, 200))
      .catch(handleError(res, 500));
  }

The way I am getting an individual Crop is this:

  public show(req: Request, res: Response) {
    return Crop.findById(req.params.id).populate({
      path: 'zones',
      populate: [
        {
          path: 'poor', populate: [
            { path: 'action_on_controls' }]
        }
      ]
    }).exec()
      .then(handleEntityNotFound(res))
      .then(respondWithResult(res, 200))
      .catch(handleError(res, 500));
  }

As you can see, the part:

.populate({..})

is repeated twice.

How can I keep the same populate configurations so I don't have to write/update the same thing all the time?

Answer 1

You can save the populate object as a variable and share it:

const zonePopulateObj = {
  path: 'zones',
  populate: [
    {
      path: 'poor', populate: [
        { path: 'action_on_controls' }]
    }
  ]
};

And then in your queries

return Crop.find().populate(zonePopulateObj).exec();

return Crop.findById(req.params.id).populate(zonePopulateObj).exec();

Or you could pull the query logic into a new function and share that

public index(req: Request, res: Response) {
    return findCrop()
      .then(respondWithResult(res, 200))
      .catch(handleError(res, 500));
  }


public show(req: Request, res: Response) {
    return findCrop(req.params.id)
      .then((array)=>array.length ? array[0] : {})
      .then(handleEntityNotFound(res)) // may need to update this function not sure how it checks for not found.
      .then(respondWithResult(res, 200))
      .catch(handleError(res, 500));
  }



  const findCrop = (id)=>{
      let queryObj = {};
      if(id){
          queryObj._id=id
      }
      return Crop.find(queryObj).populate({
        path: 'zones',
        populate: [
          {
            path: 'poor', populate: [
              { path: 'action_on_controls' }]
          }
        ]
      }).exec()
  }

Personally I prefer the first method.