Allow has_one nil association

[jeremyjung]

Attempt to fix issue #35 .

Any feedback or suggestions on where to add a test would be appreciated. I created a sample rails app to verify functionality.

[grossadamm]

Thanks @jeremyjung! If you could, could you add some tests? For guidance, I would suggest at least adding a test to object_serializer_spec

[jeremyjung]

The existing movie context (Movie, Actor, etc.) doesn’t have any has_one relations in it. I wasn’t sure if I should modify the existing models in there or create new models specifically to test has_one.

[shishirmk]

@jeremyjung @grossadamm This issue could be fixed by doing a nil check in line 12 of this file https://github.com/Netflix/fast_jsonapi/blob/master/lib/extensions/has_one.rb

Something like this

association(:#{name}).reader&.id

[jeremyjung]

@shishirmk Good call with the dig method. I'm having a little trouble figuring out the appropriate tests for this.

Putting this test in object_serializer_spec.rb doesn't interact with ActiveRecord and so it never touches the has_one extension method.

    it 'returns correct json when has_one returns nil' do
      supplier.account_id = nil
      json = SupplierSerializer.new(supplier).serialized_json
      serializable_hash = JSON.parse(json)
      expect(serializable_hash['data']['relationships']['account']['data']).to be nil
    end

Another possibility could be just testing the extension method in the active_record_spec.rb to make sure it returns nil instead of raising an exception:

    it 'has account_id method return nil if not present' do
      expect(Supplier.find(@supplier_id_without_account).account_id).to eq nil
    end

In addition, any thoughts on removing the has_one extension method completely? Without the extension method I think we could still get similar behavior by using:

    public_send(:object_method_name)&.id

[shishirmk]

@jeremyjung I think the test can go to active_record_spec.rb. The test you have in the comment looks good.

Throughout the gem we try to support serialization with just the id_method_name so that we dont have to create an object unnecessarily when we call object_method_name. It is also really helpful when we just have the id in our database and the record is in another micro service. In such cases we can serialize the record by avoiding a network call. Hope that explains why we have chosen to use this approach.

[shishirmk]

The &. Operator is available only ruby 2.3 onwards. That's why the builds are failing on 2.2.* version.

Do you mind using something more verbose?

[shishirmk]

@jeremyjung Thank you for making all the necessary changes