Apply method to all attributes using active_model_serializers

Question

Using rails-api/active_model_serializers, could one apply a method to all attributes?

Basically, I wish to apply

object.zeroed_value(:symbol) 

to each attribute without having to write a separate method for each. See example:

class NutritionalSerializer < ActiveModel::Serializer
  attributes :calories,
             :sodium

  def calories
    object.zeroed_value(:calories)
  end

  def sodium
    object.zeroed_value(:sodium)
  end

  # many, many more attributes...

end

Answer 1

I think you can use metaprogramming to generate all methods you need with something like:

class NutritionalSerializer < ActiveModel::Serializer
  attributes :calories,
             :sodium

  %i{attr1 attr2 attr3}.each do |attr|
    define_method attr do
      object.zeroed_value(attr)
    end
  end
end

Also you can override the attributes method of serializer and then do something like:

class NutritionalSerializer < ActiveModel::Serializer
  def attributes
    data = super
    %i{attr1 attr2 attr3}.each do |attr|
      data[attr] = object.zeroed_value(attr)
    end
    data
  end
end