ActiveModelSerializers Polymorphic Json

Question

Been wrestling with trying to get polymorphic serializers working and testing data via rspec. Just upgraded to 0.10+

I found this post, which makes a lot of sense, and does give me a entry into generating the serializations, however, when doing it for polymorphs, I never get the type and id properly named (expecting to see asset_id and asset_type nested)

{:id=>1,
  :label=>"Today I feel amazing!",
  :position=>0,
  :status=>"active",
  :media_container_id=>1,
  :asset=>
    {:id=>4

Test ActiveModel::Serializer classes with Rspec

class MediaSerializer < ApplicationSerializer
  attributes :id,
             :label,

  has_one :asset, polymorphic: true
end

I noticed that the tests dont even seem to properly add the polymorphic identifiers either (ie asset_id, asset_type -- or in the test case imageable_id, imageable_type)

https://github.com/rails-api/active_model_serializers/commit/045fa9bc072a04f5a94d23f3d955e49bdaba74a1#diff-c3565d7d6d40da1b2bf75e13eb8e6afbR36

If I go straight up MediaSerialzer.new(media) I can poke at the .associations, but I cant seem to get them to render as if I was generating a full payload

From the docs https://github.com/rails-api/active_model_serializers

serializer_options = {}
serializer = SomeSerializer.new(resource, serializer_options)
serializer.attributes
serializer.associations

Im pretty sure Im missing something/doing something wrong - any guidance would be great.

Thanks

Answer 1

It isn't easy to get the effect you are looking for, but it is possible.

You can access the hash generated by the serializer by overriding the associations method.

class MediaSerializer < ApplicationSerializer
  attributes :id,
             :label,

  has_one :asset, polymorphic: true

  def associations details
    data = super
    data[:asset] = relabel_asset(data[:asset])
    data
  end

  def relabel_asset asset
    labelled_asset = {}
    asset.keys.each do |k|
      labelled_asset["asset_#{k}"] = asset[k];
    end
    labelled_asset
  end
end

I learnt alot about ActiveModelSerializer to get the hang of this! I referred to Ryan Bates' podcast on the topic:

http://railscasts.com/episodes/409-active-model-serializers

In there he describes how you can override the attributes method and call super to get access to the hash generated by the serializer. I guessed I could do the same trick for the associations method mentioned in your post. From there it takes a little bit of Ruby to replace all the keys, but, if I have understood correctly what you require, it is technically possible.

Hope that helps!