Merge pull request #1343 from linovia/hotfix/1129

Fix for #1129

rest_framework/relations.py

@@ -65,16 +65,11 @@ class RelatedField(WritableField):
     def initialize(self, parent, field_name):
         super(RelatedField, self).initialize(parent, field_name)
         if self.queryset is None and not self.read_only:
-            try:
-                manager = getattr(self.parent.opts.model, self.source or field_name)
-                if hasattr(manager, 'related'):  # Forward
-                    self.queryset = manager.related.model._default_manager.all()
-                else:  # Reverse
-                    self.queryset = manager.field.rel.to._default_manager.all()
-            except Exception:
-                msg = ('Serializer related fields must include a `queryset`' +
-                       ' argument or set `read_only=True')
-                raise Exception(msg)
+            manager = getattr(self.parent.opts.model, self.source or field_name)
+            if hasattr(manager, 'related'):  # Forward
+                self.queryset = manager.related.model._default_manager.all()
+            else:  # Reverse
+                self.queryset = manager.field.rel.to._default_manager.all()
 
     ### We need this stuff to make form choices work...
 

rest_framework/tests/test_relations.py

@@ -98,3 +98,23 @@ class RelatedFieldSourceTests(TestCase):
         obj = ClassWithQuerysetMethod()
         value = field.field_to_native(obj, 'field_name')
         self.assertEqual(value, ['BlogPost object'])
+
+    # Regression for #1129
+    def test_exception_for_incorect_fk(self):
+        """
+        Check that the exception message are correct if the source field
+        doesn't exist.
+        """
+        from rest_framework.tests.models import ManyToManySource
+        class Meta:
+            model = ManyToManySource
+        attrs = {
+            'name': serializers.SlugRelatedField(
+                slug_field='name', source='banzai'),
+            'Meta': Meta,
+        }
+
+        TestSerializer = type(str('TestSerializer'),
+            (serializers.ModelSerializer,), attrs)
+        with self.assertRaises(AttributeError):
+            TestSerializer(data={'name': 'foo'})