Fix polymorphic belongs_to associationproxy raising errors when loading target.

activerecord/lib/active_record/associations/belongs_to_polymorphic_association.rb

@@ -4,6 +4,11 @@ module ActiveRecord
     class BelongsToPolymorphicAssociation < BelongsToAssociation #:nodoc:
       private
 
+        def conditions
+          @conditions ||= interpolate_sql(target_klass.send(:sanitize_sql, @reflection.options[:conditions])) if @reflection.options[:conditions]
+        end
+        alias :sql_conditions :conditions
+
         def replace_keys(record)
           super
           @owner[@reflection.foreign_type] = record && record.class.base_class.name

activerecord/test/cases/associations/belongs_to_associations_test.rb

@@ -146,6 +146,15 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     assert_not_nil Company.find(3).firm_with_condition, "Microsoft should have a firm"
   end
 
+  def test_with_polymorphic_and_condition
+    sponsor = Sponsor.create
+    member = Member.create :name => "Bert"
+    sponsor.sponsorable = member
+
+    assert_equal member, sponsor.sponsorable
+    assert_nil sponsor.sponsorable_with_conditions
+  end
+
   def test_with_select
     assert_equal Company.find(2).firm_with_select.attributes.size, 1
     assert_equal Company.find(2, :include => :firm_with_select ).firm_with_select.attributes.size, 1

activerecord/test/models/sponsor.rb

@@ -2,4 +2,6 @@ class Sponsor < ActiveRecord::Base
   belongs_to :sponsor_club, :class_name => "Club", :foreign_key => "club_id"
   belongs_to :sponsorable, :polymorphic => true
   belongs_to :thing, :polymorphic => true, :foreign_type => :sponsorable_type, :foreign_key => :sponsorable_id
+  belongs_to :sponsorable_with_conditions, :polymorphic => true,
+             :foreign_type => 'sponsorable_type', :foreign_key => 'sponsorable_id', :conditions => {:name => 'Ernie'}
 end