configure_dependency_for_has_many

# File activerecord/lib/active_record/associations.rb, line 1259
        def configure_dependency_for_has_many(reflection)
          if reflection.options.include?(:dependent)
            # Add polymorphic type if the :as option is present
            dependent_conditions = []
            dependent_conditions << "#{reflection.primary_key_name} = \#{record.quoted_id}"
            dependent_conditions << "#{reflection.options[:as]}_type = '#{base_class.name}'" if reflection.options[:as]
            dependent_conditions << sanitize_sql(reflection.options[:conditions]) if reflection.options[:conditions]
            dependent_conditions = dependent_conditions.collect {|where| "(#{where})" }.join(" AND ")

            case reflection.options[:dependent]
              when :destroy
                method_name = "has_many_dependent_destroy_for_#{reflection.name}".to_sym
                define_method(method_name) do
                  send("#{reflection.name}").each { |o| o.destroy }
                end
                before_destroy method_name
              when :delete_all
                module_eval "before_destroy { |record| #{reflection.class_name}.delete_all(%(#{dependent_conditions})) }"
              when :nullify
                module_eval "before_destroy { |record| #{reflection.class_name}.update_all(%(#{reflection.primary_key_name} = NULL),  %(#{dependent_conditions})) }"
              else
                raise ArgumentError, "The :dependent option expects either :destroy, :delete_all, or :nullify (#{reflection.options[:dependent].inspect})"
            end
          end
        end