Allow a belonging to object to be created from a new record

If a 'has one' object is created from a new record, an ActiveRecord::RecordNotSaved error is raised but this behavior was also applied to the reverse scenario.

activerecord/lib/active_record/associations/has_one_association.rb

@@ -107,6 +107,14 @@ def transaction_if(value)
             yield
           end
         end
+
+        def _create_record(attributes, raise_error = false)
+          unless owner.persisted?
+            raise ActiveRecord::RecordNotSaved, "You cannot call create unless the parent is saved"
+          end
+
+          super
+        end
     end
   end
 end

activerecord/lib/active_record/associations/singular_association.rb

@@ -63,10 +63,6 @@ def set_new_record(record)
         end
 
         def _create_record(attributes, raise_error = false)
-          unless owner.persisted?
-            raise ActiveRecord::RecordNotSaved, "You cannot call create unless the parent is saved"
-          end
-
           record = build_record(attributes)
           yield(record) if block_given?
           saved = record.save

activerecord/test/cases/associations/belongs_to_associations_test.rb

@@ -272,6 +272,15 @@ def test_creating_the_belonging_object
     assert_equal apple, citibank.firm
   end
 
+  def test_creating_the_belonging_object_from_new_record
+    citibank = Account.new("credit_limit" => 10)
+    apple    = citibank.create_firm("name" => "Apple")
+    assert_equal apple, citibank.firm
+    citibank.save
+    citibank.reload
+    assert_equal apple, citibank.firm
+  end
+
   def test_creating_the_belonging_object_with_primary_key
     client = Client.create(name: "Primary key client")
     apple  = client.create_firm_with_primary_key("name" => "Apple")