Collection representor not using property constraints of representer

[ianks]

After some digging trying to find the best way to respond_with a collection of landers... in my app I have:

module LanderRepresenter
  include Roar::Representer::JSON
  include Roar::Representer::Feature::Hypermedia

  property :name
  property :location

  link :self do
    v1_lander_url self
  end
end

module LanderCollectionRepresenter
  include Representable::JSON::Collection

  items extend: LanderRepresenter, class: Lander
end

module Api
  module V1
    class LandersController < ApplicationController
      include Roar::Rails::ControllerAdditions
      before_action :set_lander, only: [:show, :edit, :update, :destroy]
      respond_to :json

      def index
        @landers = Lander.all
        respond_with @landers, :represent_with => LanderCollectionRepresenter
      end

      def show
        respond_with @lander, :represent_with => LanderRepresenter
      end


      private

      def set_lander
        @lander = Lander.find params[:id]
      end
    end
  end
end

Is this the proper way to respond_with a collection? Rendering the LanderRepresenter works perfectly; however, when I render the collection, it spits out the entire object (without limiting the response to the property constraints on :name, :location, :link). i.e:

[{"id":1,"name":"Dr. Jeffery Skiles1","location":"http://schusterbeahan.com/eddie/1","default_offer_id":null,"created_at":"2014-09-22T20:06:26.296Z","updated_at":"2014-09-22T20:06:26.296Z"},{...},{...}]

[apotonick]

That collection document you're getting is because your collection representer is not used at all, it's Rails #to_json (hooray to Rails' magic!).

It looks as if the represent_with: option is not picked up in your respond_with call.

Can you add this, please?

module LanderCollectionRepresenter
  include Representable::JSON::Collection

  def to_json
    raise "hey, i am called!"
  end
end

[ianks]

Looks like the error was indeed raised.

wrong number of arguments (1 for 0)

def create_response(model)
  render_method = "to_#{format}"
  media_format  = Mime[format]

  # stuck on this line
  Response.new(model.send(render_method, options), media_format)
end

[apotonick]

That's great, so :represent_with works! 😄

Can you please convert LanderRepresenter into a decorator and see if that helps?

class LanderRepresenter < Roar::Decorator
  include Roar::Representer::JSON
  include Roar::Representer::Feature::Hypermedia

  property :name
  property :location

  link :self do
    v1_lander_url self
  end
end

[ianks]

Thanks for the quick response! Just tried to make it a decorator. Same issue.

I am on Rails 4.1.5 and Ruby 2.1.3 if that helps 😄

[apotonick]

Is 2.1.3 already out? 😁 I'll have a look in a couple of hours, not sure what's going on.

[ianks]

@apotonick I forgot to mention, my Lander model is not namespaced in Api::V1 like my controller. Just thought I would let you know in case that could be a source of complication.

[apotonick]

Hm, since you define it explicitely in :represent_with, it shouldn't matter where it sits.

What representable version? And what roar version?

[summera]

We are using

representable (1.8.5)
roar (0.12.9)

[ianks]

Update: confirmed this behavior on another Rails 4.1.5 app.

[summera]

@apotonick
Any word on this? @ianks and I would like to help to debug this issue.

[summera]

Turns out the issue disappeared when we namespaced our representers.

[ianks]

** namespaced our representers AND used the decorator class pattern.

[apotonick]

Does the LandersRepresenter constant exist multiple times in your app, in different namespaces?

[ianks]

No it does not.

[Danielpk]

+1

I got same issue here.

[apotonick]

I don't really know what to do here! This seems to be an autoloading/constant-referencing problem, and I still don't understand why Rails doesn't crash but uses the internal to_json instead.

Do we have any way to provoke that problem in a minimal Rails app?