'data.relationships.data' has all attributes of relationship by default when it shouldn't

[kurko]

Expected behavior vs actual behavior

I created 2 models and added has_one to the serializer, by default, it returns the relationship object:

{
  "data": {
    "id": "1", 
    "type": "posts", 
    "attributes": { "title": "my title" }, 
    "relationships": {
      "comment": { "data": { "id": "2", "name": "John", "text": "whatever" } }
    }
  }
}

However, I was expecting it to be

{
  "data": {
    "id": "1", 
    "type": "posts", 
    "attributes": {
       "title": "my title"
    }, 
    "relationships": {
      "comment": { "data": { "id": "2", "type": "comment" } }
    }
  }
}

JSONAPI specifies that

The value of the relationships key MUST be an object (a “relationships object”).

See what this means here: http://jsonapi.org/format/#document-resource-object-linkage

Basically, if I passed included, then I'd expect to see the actual objects. Otherwise it only makes sense to return the Object Linkage (which is what JSONAPI specifies anyway).

Steps to reproduce

Just create 2 serializers and add a has_one to one of them.

Environment

ActiveModelSerializers Version: 0.10.4

Integrated application and version (e.g., Rails, Grape, etc): Rails

[kurko]

Ok, found the bug. The behavior above happens when there are 2 models, 1 serializer. When I add a serializer for the second model, it shows an object linkage. Buggy nonetheless.

[bf4]

@kurko I have an idea why that's happening.. the reflection -> association -> relationship -> resourceidentifier has some dependencies on the serializer.. for a 'virtual value' it does object.as_json || object. The JSONAPI adapter shouldn't allow raw objects as associations unless it's going to try to figure it out like { type: object.class.name, object.id }

[bf4]

@kurko what do you think the expected behavior to be? JSON API associations require a serializer?

[kurko]

I don't think we should require serializers. Instead, we should just always whitelist type, id, links etc (the fields that are acceptable according to the standard). That would wipe out keys that shouldn't be there.

[bf4]

@kurko

type, id, links

where would 'type', 'id', come from, though? In #1857 (which is being superseded by #2026) I did

 if belongs_to_with_foreign_key?(association)
   id = parent_serializer.object.send(association.reflection.foreign_key)
   type = association.reflection.type.to_s

I guess, if you're ok instantiating the association object, you can do something like id = association.object.id