Fix serialization of reverse relationships

rest_framework/serializers.py

@@ -247,6 +247,19 @@ class BaseSerializer(Field):
         if not self._errors:
             return self.restore_object(attrs, instance=getattr(self, 'object', None))
 
+    def field_to_native(self, obj, field_name):
+        """
+        Override default so that we can apply ModelSerializer as a nested
+        field to relationships.
+        """
+        obj = getattr(obj, self.source or field_name)
+
+        # If the object has an "all" method, assume it's a relationship
+        if is_simple_callable(getattr(obj, 'all', None)):
+            return [self.to_native(item) for item in obj.all()]
+
+        return self.to_native(obj)
+
     @property
     def errors(self):
         """
@@ -295,16 +308,6 @@ class ModelSerializer(Serializer):
     """
     _options_class = ModelSerializerOptions
 
-    def field_to_native(self, obj, field_name):
-        """
-        Override default so that we can apply ModelSerializer as a nested
-        field to relationships.
-        """
-        obj = getattr(obj, self.source or field_name)
-        if obj.__class__.__name__ in ('RelatedManager', 'ManyRelatedManager'):
-            return [self.to_native(item) for item in obj.all()]
-        return self.to_native(obj)
-
     def default_fields(self, serialize, obj=None, data=None, nested=False):
         """
         Return all the fields that should be serialized for the model.

rest_framework/tests/models.py

@@ -92,6 +92,17 @@ class Comment(RESTFrameworkModel):
     content = models.CharField(max_length=200)
     created = models.DateTimeField(auto_now_add=True)
 
+
 class ActionItem(RESTFrameworkModel):
     title = models.CharField(max_length=200)
     done = models.BooleanField(default=False)
+
+
+# Models for reverse relations
+class BlogPost(RESTFrameworkModel):
+    title = models.CharField(max_length=100)
+
+
+class BlogPostComment(RESTFrameworkModel):
+    text = models.TextField()
+    blog_post = models.ForeignKey(BlogPost)

rest_framework/tests/serializer.py

@@ -302,3 +302,32 @@ class CallableDefaultValueTests(TestCase):
         self.assertEquals(len(self.objects.all()), 1)
         self.assertEquals(instance.pk, 1)
         self.assertEquals(instance.text, 'overridden')
+
+
+class ManyRelatedTests(TestCase):
+    def setUp(self):
+
+        class BlogPostCommentSerializer(serializers.Serializer):
+            text = serializers.CharField()
+
+        class BlogPostSerializer(serializers.Serializer):
+            title = serializers.CharField()
+            comments = BlogPostCommentSerializer(source='blogpostcomment_set')
+
+        self.serializer_class = BlogPostSerializer
+
+    def test_reverse_relations(self):
+        post = BlogPost.objects.create(title="Test blog post")
+        post.blogpostcomment_set.create(text="I hate this blog post")
+        post.blogpostcomment_set.create(text="I love this blog post")
+
+        serializer = self.serializer_class(instance=post)
+        expected = {
+            'title': 'Test blog post',
+            'comments': [
+                {'text': 'I hate this blog post'},
+                {'text': 'I love this blog post'}
+            ]
+        }
+
+        self.assertEqual(serializer.data, expected)