How do I respond with only meta data?

[ezekg]

I am using the :json_api adapter and am wanting to render only meta data for a few endpoints, e.g. responding without a top-level data key. As far as I can tell, this is allowable under the JSON API spec. I would expect to be able to do something similar to,

render: json: nil, meta: { ... }, serializer: SomeMetaSerializer

I know I could simply do,

render: json: { meta: { ... } }.to_json

but I'd like to take advantage of active model serializers automatic key transform.

Is there a way to do this that I'm just missing? Am I doing it wrong? I've attempted a few different monkey patches, but there doesn't seem to be a way to get rid of the top-level data key, even though it seems it's not explicitly required if a meta or errors key is present.

If needed, I am using Rails 5.0.0.rc1. with AMS 0.10.0.

[bf4]

I do this in my app a lot. But I just generate my JSON directly when using meta:

render_options = {}
render_options[:status] = :ok
render_options[:location] = nil
render_options[:jsonapi] = { meta: { user_id: user_id } }.to_json
render render_options

You can use the TransformKeys utility function directly:

ActiveModelSerializers::KeyTransform.camel({meta: { user_id: 5} })
=> {:Meta=>{:UserId=>5}}

But looks like this works, though I think the above is better:

ActiveModelSerializers::SerializableResource.new([], {meta: { user_id: 5 } }).as_json.except(nil)
# => { "meta" => {  user_id: 5 } }

[bf4]

If this works, please share back and improve the docs!

[ezekg]

I'm currently doing something similar but got a little frustrated with the repetition. Shouldn't we be able to render json: nil if a meta option is passed? In any case, I was able to get what I wanted by defining a helper in my ApplicationController,

def render_meta(meta)
  render json: ActiveModelSerializers::KeyTransform.camel_lower(meta: meta).to_json
end

[bf4]

json: nil makes less sense than json: {} in this scenario, since json: refers to the JSON renderer. I'm not sure how we should should handle this situation as AMS, but what you've done and what I've done works for me :)

[ezekg]

Fair enough. I'd be happy to add something in the docs about this. Any place in particular I should add that in, just another section under the docs/howto directory?

[remear]

@ezekg Sure, that sounds like a good place to start.