1 files changed, 32 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/associations/builder/singular_association.rb b/activerecord/lib/active_record/associations/builder/singular_association.rb
new file mode 100644
index 0000000000..06a414b874
--- /dev/null
+++ b/activerecord/lib/active_record/associations/builder/singular_association.rb
@@ -0,0 +1,32 @@
+module ActiveRecord::Associations::Builder
+  class SingularAssociation < Association #:nodoc:
+    self.valid_options += [:remote, :dependent, :counter_cache, :primary_key, :inverse_of]
+
+    def constructable?
+      true
+    end
+
+    def define_accessors
+      super
+      define_constructors if constructable?
+    end
+
+    private
+
+      def define_constructors
+        name = self.name
+
+        model.redefine_method("build_#{name}") do |*params|
+          association(name).build(*params)
+        end
+
+        model.redefine_method("create_#{name}") do |*params|
+          association(name).create(*params)
+        end
+
+        model.redefine_method("create_#{name}!") do |*params|
+          association(name).create!(*params)
+        end
+      end
+  end
+end