Fixed bug in active_record/nested_attributes where an empty string id caused an ActiveRecord::RecordNotFound error. Found by [Ben Tillman]

[#5638 state:committed]

Signed-off-by: Santiago Pastorino <santiago@wyeworks.com>

activerecord/lib/active_record/nested_attributes.rb

@@ -323,7 +323,7 @@ module ActiveRecord
           (options[:update_only] || record.id.to_s == attributes['id'].to_s)
         assign_to_or_mark_for_destruction(record, attributes, options[:allow_destroy]) unless call_reject_if(association_name, attributes)
 
-      elsif attributes['id']
+      elsif not attributes['id'].blank?
         raise_nested_attributes_record_not_found(association_name, attributes['id'])
 
       elsif !reject_new_record?(association_name, attributes)

activerecord/test/cases/nested_attributes_test.rb

@@ -139,6 +139,14 @@ class TestNestedAttributesInGeneral < ActiveRecord::TestCase
     assert_equal 'gardening', interest.reload.topic
   end
 
+  def test_reject_if_with_blank_nested_attributes_id
+    # When using a select list to choose an existing 'ship' id, with :include_blank => true
+    Pirate.accepts_nested_attributes_for :ship, :reject_if => proc {|attributes| attributes[:id].blank? }
+
+    pirate = Pirate.new(:catchphrase => "Stop wastin' me time")
+    pirate.ship_attributes = { :id => "" }
+    assert_nothing_raised(ActiveRecord::RecordNotFound) { pirate.save! }
+  end
 end
 
 class TestNestedAttributesOnAHasOneAssociation < ActiveRecord::TestCase