Cannot Memoize Methods

[richmolj]

attribute :foo do
  memo_method
end

def memo_method
  @memo ||= 'adsf'
end

Will raise error RuntimeError: can't modify frozen ..., due to this #freeze call. Is there a downside to removing the freeze?

[Startouf]

Hey, any news on this ? What's the recommended way to perform memoisation in serializers ?

Right now our solution is to memoize on the model but this feels dirty.

[ClayShentrup]

Yeah this is frustrating. I just do a presenter.

class SerializablePortalFile < JSONAPI::Serializable::Resource
  type('portal_files')

  attributes(:kind)

  attribute(:current_version) do
    @object.version
  end

  attribute(:fields) do
    @object.rows.each_with_index.map do |row, i|
      key = row.fetch('0')
      {
        name: key,
        value: row.fetch('1'),
        masked?: @object.masks.fetch(i)
      }
    end
  end

  def initialize(object:, **args)
    super(object: Presenter.new(object), **args)
  end

  # Adds helper methods to the PortalFile.
  class Presenter < SimpleDelegator
    def rows
      rows_including_empty_last_row.tap(&:pop)
    end

    def rows_including_empty_last_row
      contents_as_json.fetch(:rows)
    end

    def masks
      @masks ||= meta_data.fetch('masks')
    end
  end
end

[wuarmin]

You could implement a decorator/presenter pattern, which is responsible for memoizing and used as model of the serializer. With that you keep your model clean and independent of jsonapi.

[ClayShentrup]

You could implement a decorator/presenter pattern

Indeed that is exactly what my code does there. The presenter class is called Presenter.

[wuarmin]

You could implement a decorator/presenter pattern

Indeed that is exactly what my code does there. The presenter class is called Presenter.

Oh sorry, I overlooked that. I had an experience with another json-api-serializing-gem with the same problem. In the meantime I don't see it as a disadvantage to implement presenters between the models and the view-serializers.