JsonApi PaginationLinks doesn't work outside of ActionController

[jpaas]

I'm trying to use Grape+Kaminari+AMS 1.0 (head) and I get a stack trace like so...

(NoMethodError)undefined method `query_parameters' for nil:NilClass
/Users/jpaas/.rvm/gems/ruby-2.2.2@imdcloud/bundler/gems/active_model_serializers-da7e6dc795ac/lib/active_model/serializer/adapter/json_api/pagination_links.rb:52:in `query_parameters'
/Users/jpaas/.rvm/gems/ruby-2.2.2@imdcloud/bundler/gems/active_model_serializers-da7e6dc795ac/lib/active_model/serializer/adapter/json_api/pagination_links.rb:17:in `block in serializable_hash'
/Users/jpaas/.rvm/gems/ruby-2.2.2@imdcloud/bundler/gems/active_model_serializers-da7e6dc795ac/lib/active_model/serializer/adapter/json_api/pagination_links.rb:16:in `each'
/Users/jpaas/.rvm/gems/ruby-2.2.2@imdcloud/bundler/gems/active_model_serializers-da7e6dc795ac/lib/active_model/serializer/adapter/json_api/pagination_links.rb:16:in `each_with_object'
/Users/jpaas/.rvm/gems/ruby-2.2.2@imdcloud/bundler/gems/active_model_serializers-da7e6dc795ac/lib/active_model/serializer/adapter/json_api/pagination_links.rb:16:in `serializable_hash'
/Users/jpaas/.rvm/gems/ruby-2.2.2@imdcloud/bundler/gems/active_model_serializers-da7e6dc795ac/lib/active_model/serializer/adapter/json_api.rb:212:in `links_for'
/Users/jpaas/.rvm/gems/ruby-2.2.2@imdcloud/bundler/gems/active_model_serializers-da7e6dc795ac/lib/active_model/serializer/adapter/json_api.rb:103:in `serializable_hash_for_collection'
/Users/jpaas/.rvm/gems/ruby-2.2.2@imdcloud/bundler/gems/active_model_serializers-da7e6dc795ac/lib/active_model/serializer/adapter/json_api.rb:61:in `serializable_hash'
/Users/jpaas/.rvm/gems/ruby-2.2.2@imdcloud/bundler/gems/active_model_serializers-da7e6dc795ac/lib/active_model/serializable_resource.rb:14:in `serializable_hash'

It seems to assume that the context has been set as an ActionDispatch::Request. I would try setting it, but I can't figure out how to get it in Grape.

[jpaas]

Looking at the code, I can't even see how this would work for ActionController. The SerializableResource filters the adapter options, so that they must be one of [:include, :fields, :adapter, :meta, :meta_key, :links]. Which means there's no way the adapter options could contain a :context entry.

[bf4]

@jpaas good bug report. https://github.com/rails-api/active_model_serializers/blob/da7e6dc795ac4f6eb0af63c19c46638b13d0d04e/test/action_controller/json_api/pagination_test.rb should cover that it works

I agree that we are sometime too eager to add foreign objects to the app. It should really be encapsulated. context should maybe be called 'request_context' and has two methods we use: original_url and query_parameters

• How are you integrating see Grape with AMS

[jpaas]

I was using a fork of grape-active_model_serializers https://github.com/Thanx/grape-active_model_serializers.git, but once I started using the jsonapi adapter, I built my own very simple grape json formatter:

module API
  module AmsFormatter
    class << self
      def call(resource, env)
        serializer_options = {}
        serializer_options.merge!(env['ams_serializer_options']) if env['ams_serializer_options']
        # For some reason serializable_hash doesn't include meta in the response, so I have to use as_json
        ActiveModel::SerializableResource.new(resource, serializer_options).as_json.to_json
      end
    end
  end
end

I also had to create this little grape helper to pass my serializer options to the formatter via the env:

        def render(resources, ams_serializer_options = {})
          env['ams_serializer_options'] = ams_serializer_options
          resources
        end

So now I can implement a grape endpoint like this and put metadata into the jsonapi response:

    formatter :json, API::AmsFormatter

     get ':id' do
       render(Resource.find(params[:id]), meta: { foo: 'bar' })
     end

[jpaas]

Oh and BTW, my workaround for this problem at the moment was to subclass the JsonApi adapter to simply skip links for now...

module API
  class AmsJsonapiAdapter < ActiveModel::Serializer::Adapter::JsonApi
    def links_for(serializer, options)
      {}
    end
  end
end

[bf4]

@jpaas would you want to submit the formatter here as a PR?

Also, you should be able to just to_json not as_json.to_json

[jpaas]

Ah yes @bf4 to_json alone works. I thought I tried that at one point but had trouble. I can submit as a PR. Where would you like it in the namespace?

[bf4]

I'm thinking Grape::ActiveModelSerializers in lib/grape/active_model_serializers or something like that and maybe in lib grape-active_model_serializers.rb that requires active_model_serializers and grape/active_model_serializers. Just try something that makes sense to you

[hut8]

I just spent like 6 hours figuring this out. I'm using the same set of tools as @jpaas and I can get the links to work if I pass in the (bastardized) context where I would least expect it ⁉️

So I changed the code at #1268 (comment) to:

# A grape response formatter that can be used as 'formatter :json, Grape::Formatters::ActiveModelSerializers'
#                                                                                                                                                                                # Serializer options can be passed as a hash from your grape endpoint using env[:active_model_serializer_options],
# or better yet user the render helper in Grape::Helpers::ActiveModelSerializers
module Grape
  module Formatters
    module ActiveModelSerializers
      RequestContext = Struct.new(:original_url, :query_parameters)                                                                                                              
      class << self
        def call(resource, env)                                                                                                                                                            serializer_options = {}
          serializer_options.merge!(env[:active_model_serializer_options]) if env[:active_model_serializer_options]

          serializer_options[:context] = RequestContext.new(env['REQUEST_URI'],
                                                            env['rack.request.query_hash'])
          ActiveModel::SerializableResource.new(resource, serializer_options).to_json(serializer_options)
        end
      end
    end
  end
end

Without passing my little context hack into to_json, they don't make their way into PaginationLinks's context constructor parameter. Interestingly, when I pass them to as_json instead, I get Ruby out! 😮