Ticket #17879: ticket17439.patch

django/core/serializers/python.py

@@ -47 +47 @@
     def handle_fk_field(self, obj, field):
         if self.use_natural_keys and hasattr(field.rel.to, 'natural_key'):
             related = getattr(obj, field.name)
-            value = related.natural_key()
+            if related:
+                value = related.natural_key()
+            else:
+                value = None
         else:
             value = getattr(obj, field.get_attname())
         self._current[field.name] = value

tests/regressiontests/serializers_regress/models.py

@@ -272 +272 @@
 
     def __len__(self):
         return self.data
+
+class PersonManager(models.Manager):
+    def get_by_natural_key(self, first_name, last_name):
+        return self.get(first_name=first_name, last_name=last_name)
+
+class Person(models.Model):
+    objects = PersonManager()
+
+    first_name = models.CharField(max_length=100)
+    last_name = models.CharField(max_length=100)
+
+    class Meta:
+        unique_together = (('first_name', 'last_name'),)
+
+    def natural_key(self):
+        return (self.first_name, self.last_name)
+
+class Car(models.Model):
+    owner = models.ForeignKey(Person, null=True)
+

tests/regressiontests/serializers_regress/tests.py

@@ -42 +42 @@
     PositiveSmallIntegerPKData, SlugPKData, SmallPKData, USStatePKData,
     AutoNowDateTimeData, ModifyingSaveData, InheritAbstractModel, BaseModel,
     ExplicitInheritBaseModel, InheritBaseModel, ProxyBaseModel,
-    ProxyProxyBaseModel, BigIntegerData, LengthModel, Tag, ComplexModel)
+    ProxyProxyBaseModel, BigIntegerData, LengthModel, Tag, ComplexModel, Person, Car)
 
 # A set of functions that can be used to recreate
 # test data objects of various kinds.
@@ -485 +485 @@
     setattr(SerializerTests, 'test_' + format + '_serializer_fields', curry(fieldsTest, format))
     if format != 'python':
         setattr(SerializerTests, 'test_' + format + '_serializer_stream', curry(streamTest, format))
+
+
+class NaturalKeyTest(TestCase):
+    def setUp(self):
+        self.person = Person.objects.create(first_name='John', last_name='Doe')
+
+    def test_fk_to_natural_key_model(self):
+        """This is included just for posterity"""
+        obj = Car.objects.create(owner=self.person)
+        string_data = serializers.serialize(format, [obj], use_natural_keys=True)
+        self.assertEqual(string_data, '[{"pk": 1, "model": "serializers_regress.car", "fields": {"owner": ["John", "Doe"]}}]')
+
+    def test_null_fk_to_natural_key_model(self):
+        obj = Car.objects.create()
+        string_data = serializers.serialize(format, [obj], use_natural_keys=True)
+        self.assertEqual(string_data, '[{"pk": 1, "model": "serializers_regress.car", "fields": {"owner": null}}]')
+