This initializer patches the Rails bug described in ticket 5674

fix_habtm_join_table_deletion_order.rb

# This initializer patches the bug described in ticket 5674:
# https://rails.lighthouseapp.com/projects/8994/tickets/5674-regression-habtm-deletion-fails-when-join-table-has-foreign-keys

if Rails.version == '3.0.0'
  module ActiveRecord::Associations
    autoload :HasAndBelongsToManyAssociation, 'active_record/associations/has_and_belongs_to_many_association'

    module ClassMethods
      def has_and_belongs_to_many(association_id, options = {}, &extension)
        reflection = create_has_and_belongs_to_many_reflection(association_id, options, &extension)
        collection_accessor_methods(reflection, HasAndBelongsToManyAssociation)

        # Don't use a before_destroy callback since users' before_destroy
        # callbacks will be executed after the association is wiped out.
        include Module.new {
          class_eval <<-RUBY, __FILE__, __LINE__ + 1
            def destroy                     # def destroy
              #{reflection.name}.clear      #   posts.clear
              super                         #   super
            end                             # end
          RUBY
        }

        add_association_callbacks(reflection.name, options)
      end
    end
  end
end