active_model_serializers

ActiveModel::Serializer#to_hash

associations, similar to how ActiveModel::Serializers::JSON is used
in ActiveRecord::Base.

TODO: Move to here the Attributes adapter logic for
+serializable_hash_for_single_resource(options)+
and include <tt>ActiveModel::Serializers::JSON</tt>.
So that the below is true:
  @param options [nil, Hash] The same valid options passed to `serializable_hash`
     (:only, :except, :methods, and :include).

    See
    https://github.com/rails/rails/blob/v5.0.0.beta2/activemodel/lib/active_model/serializers/json.rb#L17-L101
    https://github.com/rails/rails/blob/v5.0.0.beta2/activemodel/lib/active_model/serialization.rb#L85-L123
    https://github.com/rails/rails/blob/v5.0.0.beta2/activerecord/lib/active_record/serialization.rb#L11-L17
    https://github.com/rails/rails/blob/v5.0.0.beta2/activesupport/lib/active_support/core_ext/object/json.rb#L147-L162

  @example
    # The :only and :except options can be used to limit the attributes included, and work
    # similar to the attributes method.
    serializer.as_json(only: [:id, :name])
    serializer.as_json(except: [:id, :created_at, :age])

    # To include the result of some method calls on the model use :methods:
    serializer.as_json(methods: :permalink)

    # To include associations use :include:
    serializer.as_json(include: :posts)
    # Second level and higher order associations work as well:
    serializer.as_json(include: { posts: { include: { comments: { only: :body } }, only: :title } })

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