Include type and id for relationship, without full resource include

[camjackson]

In my response, I want to include relationship information in the main resource, but I don't want to include the whole resource in the "included" section, mostly because the other resource has no attributes, so it's redundant.

I.e., I want to generate a response that looks like the following:

{
    "data": {
        "id": "5",
        "type": "things",
        "attributes": {
            "name": "A Thing",
        },
        "links": {
            "self": "/things/5"
        },
        "relationships": {
            "otherThing": {
                "data": {
                    "type": "otherThings",
                    "id": "123"
                }
            }
        }
    }
}

When I serialize without any :include, then I get:

    "relationships": {
        "otherThing": {
        }
    }

When I serialize with include: 'otherThing', then I get:

    "relationships": {
        "otherThing": {
            "type": "otherThings",   <--- I want this information
            "id": "123"              <--- and also this
        }
    }
"included": [    <--- But I don't need any of this
    {
        "type": "otherThings",
        "id": "123",
        "attributes": {},
        "links": {
            "self": "/otherThings/123"
        }
    }
]

Is there a way to get this middleground?

[hspazio]

@camjackson I've opened a PR here that might be the middleground you are asking. It supports custom serializers for 'has_one' and 'has_many' relationships (rather than including the full list of attributes).

Perhaps something like this would work for you?

# serializers/thing_serializer.rb
class ThingSerializer
  include JSONAPI::Serializer

  attribute :name

  has_many :other_things, serializer: OtherThingMinifiedSerializer
end

# serializers/other_thing_minified_serializer.rb
# this should not include any attributes BUT the resource will
# still appear in the 'included' section.
class OtherThingMinifiedSerializer
  include JSONAPI::Serializer
end

It's been queued for @fotinakis for review.

[camjackson]

@hspazio Ideally I'd like to exclude the resource from the included block altogether, as my primary reason for requesting this is for a particular resource type that has no attributes (just an id).

I can think of four different levels of detail:

1. Don't even mention that the relationship is there at all
2. Mention that the relationship exists, but provide no further information about it
3. Provide the reference data for the relationship (i.e. id & type), so that it can be fetched later
4. As above, but also provide the full resource in the included section (along

To me, options 3 & 4 seem the most useful, but I could also see an argument for option 1 if you really don't care about the relationship, and it doesn't make sense to include it at all.

However, I can't see how option 2 (which is the behaviour you currently get with no :include argument) would ever be useful? It's quite possible that I'm totally missing something though :)

But yeah, option 3 is what I really want, but I don't think it's possible at the moment.

All of that said, with a very general library like this if you give builtin options for every single possible use case, it can become a bit of a monster. So perhaps the custom serializer approach is a better one. Writing my own custom implementations for things like base_url has been working very well for me so far.

[lucasm-iRonin]

Maybe some options provided to has_one / has_many could allow to enable / disable data for relationships no matter whether it's included or not?

[fotinakis]

@camjackson FYI, this is being worked on in #62