Separate accessor for referenced object from foreign key accessor

[lackac]

I like the new populate functionality. It makes our code so much more readable. Our schema doesn't map well to how it works though.

Consider this schema:

var BrandSchema = new Schema({ name: String });
var ProductSchema = new Schema({
    brand_id: { type: Schema.ObjectId, ref: 'Brand' }
  , name: String
  , description: String
});

Now if I use populate with this schema, it starts to look really weird:

Product.findOne().populate('brand_id').run(function(err, product) {

  console.log(product.brand_id); // <-- this is now a brand object

  var brand = new Brand({_id: 'levis', name: "Levi's"});
  product.brand_id = brand;      // <-- I'm assigning a brand object to the brand_id property

  console.log(product.brand_id); // <-- this is now a brand id

  product.save(function() {});
});

I've created a monkey patch to resolve this situation. It restores populated references to their 'id state' and creates an accessor for the populated object. It only supports references which end in _id (e.g. brand_id).

I would be happy to integrate this into core or create a plugin for it. Whichever is more appropriate.

Some limitations of my current approach:

• it only supports references the names of which end in _id
• it's not clear how this should handle collections
• probably doesn't handle many cases

Further ideas for a more complete implementation:

• ref accessors could be declared in the schema definition with something like this: brand: { refProp: 'brand_id' }
• if the query wasn't run with populate the accessor could do an implicit fetch on first get and return a promise for the object
• alternatively it could return null and a separate fetch method would be available for populating references on an initialized object

[lackac]

this is related to #570

[trungpham]

what is the status of this? i am running into the same problem too. thanks.

[wookets]

I have the same issue. What is the solution? It seems like this is a pretty common use case when using populate. ID -> populated object, go to save and it says, "Error: Invalid ObjectID"

Is everyone just rolling a custom solution to get around this?

[aheckmann]

In 3.6, setting a populated path to a document will no longer cast to its _id.