Sparse fields don't work with non-single-word types

[kitsuneyo]

Expected Behavior

Requests for a sparse fieldset to a resource with a type that includes two words, e.g. personAlias, should only return the specified fields.

Example request:

GET /person-aliases?fields[personAlias]=myField

Expected response:

{
    "data": [
        {
            "id": "1",
            "type": "personAlias",
            "attributes": {
                "myField": "foo"
            }
       }
    ]
}

Note that:

• I'm using jsonapi.rb alongside jsonapi-serializer
• My serializers have the option set_key_transform :camel_lower
• I've manually set the the type in my serializers e.g. set_type :person_alias
• A request with the type given in snake_case, e.g. GET /person-aliases?fields[person_alias]=myField or GET /person-aliases?fields[person_alias]=my_field, does not work either

If I manually set a one-word type, e.g. set_type :foo, things work as expected.

Actual Behavior

The response includes all fields, not the sparse fieldset requested, for example:

{
    "data": [
        {
            "id": "1",
            "type": "personAlias",
            "attributes": {
                "myField": "foo",
                "myOtherField": "foo",
                "anotherOne": "foo",
            }
       }
    ]
}

Steps to Reproduce the Problem

1. In the serializer, add options set_type :foo_bar and set_key_transform :camel_lower
2. In the controller, include JSONAPI::Fetching etc. and render with render jsonapi: result, status: :ok

Specifications

• Version: 1.7.0
• Ruby version: 2.7.1

[stas]

Hey @kitsuneyo

Before we dig in to this, the set_key_transform :camel_lower doesn't affect the values, just the keys!

Another thing here is that this doesn't look like a jsonapi.rb issue, since the library barely calls the jsonapi-serializer based on the params it extracts from the request. In which case, I suggest you file an issue at https://github.com/jsonapi-serializer/jsonapi-serializer (here's the related test-case if you want to give it a try: https://github.com/jsonapi-serializer/jsonapi-serializer/blob/master/spec/integration/attributes_fields_spec.rb#L43 )

Second, the request in your example doesn't seem correct.

GET /person-aliases?fields[personAlias]=myField
                               ^- this should be the value you set with `set_type`, eg. `person_alias`
                                       

Consider this updated example:

GET /person-aliases?fields[person_alias]=myField

Alternatively, as the library doesn't have a lot of tests with custom key transformation support, I suggest to give it a try without changing the key transformation method and see if it works.

Let me know how did it go. Thanks!

[kitsuneyo]

Thanks for the quick reply.

Before we dig in to this, the set_key_transform :camel_lower doesn't affect the values, just the keys!

In the case of type, I promise you it does! If I comment out set_key_transform :camel_lower, then my type value personAlias becomes person_alias. But that is a jsonapi-serializer thing.

Consider this updated example: GET /person-aliases?fields[person_alias]=myField

It doesn't work, I had already tried it :(

Alternatively, as the library doesn't have a lot of tests with custom key transformation support, I suggest to give it a try without changing the key transformation method and see if it works.

It does work! I'll investigate more, thanks for the hints.

[kitsuneyo]

I think this is actually a duplicate of jsonapi-serializer/jsonapi-serializer#119.