1 files changed, 63 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/associations/builder/has_many.rb b/activerecord/lib/active_record/associations/builder/has_many.rb
new file mode 100644
index 0000000000..77bb66228d
--- /dev/null
+++ b/activerecord/lib/active_record/associations/builder/has_many.rb
@@ -0,0 +1,63 @@
+module ActiveRecord::Associations::Builder
+  class HasMany < CollectionAssociation #:nodoc:
+    self.macro = :has_many
+
+    self.valid_options += [:primary_key, :dependent, :as, :through, :source, :source_type, :inverse_of]
+
+    def build
+      reflection = super
+      configure_dependency
+      reflection
+    end
+
+    private
+
+      def configure_dependency
+        if options[:dependent]
+          unless [:destroy, :delete_all, :nullify, :restrict].include?(options[:dependent])
+            raise ArgumentError, "The :dependent option expects either :destroy, :delete_all, " \
+                                 ":nullify or :restrict (#{options[:dependent].inspect})"
+          end
+
+          send("define_#{options[:dependent]}_dependency_method")
+          model.before_destroy dependency_method_name
+        end
+      end
+
+      def define_destroy_dependency_method
+        name = self.name
+        model.send(:define_method, dependency_method_name) do
+          send(name).each do |o|
+            # No point in executing the counter update since we're going to destroy the parent anyway
+            counter_method = ('belongs_to_counter_cache_before_destroy_for_' + self.class.name.downcase).to_sym
+            if o.respond_to?(counter_method)
+              class << o
+                self
+              end.send(:define_method, counter_method, Proc.new {})
+            end
+          end
+
+          send(name).delete_all
+        end
+      end
+
+      def define_delete_all_dependency_method
+        name = self.name
+        model.send(:define_method, dependency_method_name) do
+          send(name).delete_all
+        end
+      end
+      alias :define_nullify_dependency_method :define_delete_all_dependency_method
+
+      def define_restrict_dependency_method
+        name = self.name
+        model.send(:define_method, dependency_method_name) do
+          raise ActiveRecord::DeleteRestrictionError.new(name) unless send(name).empty?
+        end
+      end
+
+      def dependency_method_name
+        "has_many_dependent_for_#{name}"
+      end
+  end
+end