Reform ActiveAdmin Extensions

destroyable.rb

module Form
  module Destroyable
    extend ActiveSupport::Concern

    included do
      # This is deprecated, what's the replacement?
      property :_destroy, virtual: true
    end

    def new_record?
      model.new_record?
    end

    def marked_for_destruction?
      true_values.include? _destroy
    end

    def destroy
      model.destroy
    end

    def save_model
      destroy and return if marked_for_destruction?

      super
    end
  end
end

reflections.rb

module Form
  module Reflections
    extend ActiveSupport::Concern

    def initialize(model = nil)
      model ? super : super(model_class.new)
    end

    def model_class
      self.class.model_class
    end

    module ClassMethods
      def reflect_on_association(association)
        # The idea here is to trick `reflect_on_association`
        # to get a form object. The fundamental reason why is
        # that using AA::FormBuilder#has_many hits this method
        # and exposes the underlying model.
        reflection = Reflection.new(model_name, association)

        reflection.association_form
      end

      def klass
        self
      end

      def model_class
        model_name.name.constantize
      end
    end

    class Reflection
      attr_reader :klass, :association

      def initialize(model, association)
        @klass = constantize(model.name)
        @association = association
      end

      def association_form
        return unless association_model

        constantize(association_form_name)
      end

      def association_model
        return unless klass

        reflection = klass.reflect_on_association(association)
        return unless reflection

        reflection.klass
      end

      def association_form_name
        "#{association_model}Form"
      end

      def constantize(name)
        # This is usually bad practice but the whole
        # point of `reflect_on_association` is to return nil
        # when nothing is found, this ensures just that.
        name.constantize rescue nil
      end
    end
  end
end