Refactored nested attributes a bit around :reject_if => :all_blank.

activerecord/lib/active_record/nested_attributes.rb

@@ -188,6 +188,8 @@ class TooManyRecords < ActiveRecordError
     # the parent model is saved. This happens inside the transaction initiated
     # by the parents save method. See ActiveRecord::AutosaveAssociation.
     module ClassMethods
+      REJECT_ALL_BLANK_PROC = proc { |attributes| attributes.all? { |_, value| value.blank? } }
+
       # Defines an attributes writer for the specified association(s). If you
       # are using <tt>attr_protected</tt> or <tt>attr_accessible</tt>, then you
       # will need to add the attribute writer to the allowed list.
@@ -229,6 +231,7 @@ def accepts_nested_attributes_for(*attr_names)
         options = { :allow_destroy => false, :update_only => false }
         options.update(attr_names.extract_options!)
         options.assert_valid_keys(:allow_destroy, :reject_if, :limit, :update_only)
+        options[:reject_if] = REJECT_ALL_BLANK_PROC if options[:reject_if] == :all_blank
 
         attr_names.each do |association_name|
           if reflection = reflect_on_association(association_name)
@@ -241,11 +244,7 @@ def accepts_nested_attributes_for(*attr_names)
 
             reflection.options[:autosave] = true
             add_autosave_association_callbacks(reflection)
-            self.nested_attributes_options[association_name.to_sym] = options
-
-            if options[:reject_if] == :all_blank
-              self.nested_attributes_options[association_name.to_sym][:reject_if] = proc { |attributes| attributes.all? {|k,v| v.blank?} }
-            end
+            nested_attributes_options[association_name.to_sym] = options
 
             # def pirate_attributes=(attributes)
             #   assign_nested_attributes_for_one_to_one_association(:pirate, attributes)

activerecord/test/cases/nested_attributes_test.rb

@@ -34,7 +34,10 @@ def test_base_should_have_an_empty_nested_attributes_options
   end
 
   def test_should_add_a_proc_to_nested_attributes_options
-    [:parrots, :birds, :birds_with_reject_all_blank].each do |name|
+    assert_equal ActiveRecord::NestedAttributes::ClassMethods::REJECT_ALL_BLANK_PROC,
+                 Pirate.nested_attributes_options[:birds_with_reject_all_blank][:reject_if]
+    
+    [:parrots, :birds].each do |name|
       assert_instance_of Proc, Pirate.nested_attributes_options[name][:reject_if]
     end
   end