use quoted id of single AR::Base objects in predicates

2 files changed, 8 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/relation/predicate_builder.rb b/activerecord/lib/active_record/relation/predicate_builder.rb
index c5428dccd6..2eda404490 100644
--- a/activerecord/lib/active_record/relation/predicate_builder.rb
+++ b/activerecord/lib/active_record/relation/predicate_builder.rb
@@ -25,6 +25,8 @@ module ActiveRecord
             attribute.in(values)
           when Range, Arel::Relation
             attribute.in(value)
+          when ActiveRecord::Base
+            attribute.eq(value.quoted_id)
           else
             attribute.eq(value)
           end
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index b44c716db8..13c26a0c15 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -426,6 +426,12 @@ class RelationTest < ActiveRecord::TestCase
     assert_blank authors.all
   end
 
+  def test_where_with_ar_object
+    author = Author.first
+    authors = Author.scoped.where(:id => author)
+    assert_equal 1, authors.all.length
+  end
+
   def test_exists
     davids = Author.where(:name => 'David')
     assert davids.exists?