From 85ab68c69dd7e172b2c74d2c4e3d6f268ca1b9fa Mon Sep 17 00:00:00 2001
From: Tanel Suurhans <tanel.suurhans@perfectline.ee>
Date: Fri, 30 Apr 2010 12:10:21 +0300
Subject: [PATCH] Fix issues with polymorphic belongs_to blank parameters [#4503:resolved]

---
 .../belongs_to_polymorphic_association.rb          |    4 +-
 .../associations/belongs_to_associations_test.rb   |   21 +++++++++++++++++++-
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb b/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
index f6edd63..b8c68fe 100644
--- a/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
+++ b/activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb
@@ -2,7 +2,7 @@ module ActiveRecord
   module Associations
     class BelongsToPolymorphicAssociation < AssociationProxy #:nodoc:
       def replace(record)
-        if record.nil?
+        if record.blank?
           @target = @owner[@reflection.primary_key_name] = @owner[@reflection.options[:foreign_type]] = nil
         else
           @target = (AssociationProxy === record ? record.target : record)
@@ -70,7 +70,7 @@ module ActiveRecord
         end
 
         def association_class
-          @owner[@reflection.options[:foreign_type]] ? @owner[@reflection.options[:foreign_type]].constantize : nil
+          @owner[@reflection.options[:foreign_type]].present? ? @owner[@reflection.options[:foreign_type]].constantize : nil
         end
     end
   end
diff --git a/activerecord/test/cases/associations/belongs_to_associations_test.rb b/activerecord/test/cases/associations/belongs_to_associations_test.rb
index ab0edee..60ef05d 100644
--- a/activerecord/test/cases/associations/belongs_to_associations_test.rb
+++ b/activerecord/test/cases/associations/belongs_to_associations_test.rb
@@ -357,7 +357,7 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     assert_raise(ActiveRecord::ReadOnlyRecord) { companies(:first_client).readonly_firm.save! }
     assert companies(:first_client).readonly_firm.readonly?
   end
-  
+
   def test_polymorphic_assignment_foreign_type_field_updating
     # should update when assigning a saved record
     sponsor = Sponsor.new
@@ -410,6 +410,25 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     assert_equal nil, essay.writer_id
   end
 
+  def test_polymorphic_assigment_with_blank_object_and_attributes
+    sponsor = Sponsor.new
+
+    assert_nothing_raised do
+      sponsor.sponsorable = ""
+    end
+
+    assert_equal nil, sponsor.sponsorable
+
+    sponsor.sponsorable_id = ""
+    sponsor.sponsorable_type = ""
+    sponsor.save
+    sponsor.reload
+
+    assert_nothing_raised do
+      sponsor.sponsorable
+    end
+  end
+
   def test_belongs_to_proxy_should_not_respond_to_private_methods
     assert_raise(NoMethodError) { companies(:first_firm).private_method }
     assert_raise(NoMethodError) { companies(:second_client).firm.private_method }
-- 
1.7.0.5