Fix for field to make it easier to access field relationships

rest_framework/fields.py

@@ -83,6 +83,10 @@ class Field(object):
 
         if is_protected_type(value):
             return value
+
+        all_callable = getattr(value, 'all', None)
+        if is_simple_callable(all_callable):
+            return [self.to_native(item) for item in value.all()]
         elif hasattr(value, '__iter__') and not isinstance(value, (dict, basestring)):
             return [self.to_native(item) for item in value]
         return smart_unicode(value)
@@ -197,7 +201,7 @@ class ModelField(WritableField):
         value = self.model_field._get_val_from_obj(obj)
         if is_protected_type(value):
             return value
-        return self.model_field.value_to_string(self.obj)
+        return self.model_field.value_to_string(obj)
 
     def attributes(self):
         return {

rest_framework/tests/genericrelations.py

+from django.test import TestCase
+from rest_framework import serializers
+from rest_framework.tests.models import *
+
+
+class TestGenericRelations(TestCase):
+    def setUp(self):
+        bookmark = Bookmark(url='https://www.djangoproject.com/')
+        bookmark.save()
+        django = Tag(tag_name='django')
+        django.save()
+        python = Tag(tag_name='python')
+        python.save()
+        t1 = TaggedItem(content_object=bookmark, tag=django)
+        t1.save()
+        t2 = TaggedItem(content_object=bookmark, tag=python)
+        t2.save()
+        self.bookmark = bookmark
+
+    def test_reverse_generic_relation(self):
+        class BookmarkSerializer(serializers.ModelSerializer):
+            tags = serializers.Field(source='tags')
+
+            class Meta:
+                model = Bookmark
+                exclude = ('id',)
+
+        serializer = BookmarkSerializer(instance=self.bookmark)
+        expected = {
+            'tags': [u'django', u'python'],
+            'url': u'https://www.djangoproject.com/'
+        }
+        self.assertEquals(serializer.data, expected)

rest_framework/tests/models.py

 from django.db import models
+from django.contrib.contenttypes.models import ContentType
+from django.contrib.contenttypes.generic import GenericForeignKey, GenericRelation
+
 # from django.contrib.auth.models import Group
 
 
@@ -59,3 +62,24 @@ class CallableDefaultValueModel(RESTFrameworkModel):
 
 class ManyToManyModel(RESTFrameworkModel):
     rel = models.ManyToManyField(Anchor)
+
+# Models to test generic relations
+
+
+class Tag(RESTFrameworkModel):
+    tag_name = models.SlugField()
+
+
+class TaggedItem(RESTFrameworkModel):
+    tag = models.ForeignKey(Tag, related_name='items')
+    content_type = models.ForeignKey(ContentType)
+    object_id = models.PositiveIntegerField()
+    content_object = GenericForeignKey('content_type', 'object_id')
+
+    def __unicode__(self):
+        return self.tag.tag_name
+
+
+class Bookmark(RESTFrameworkModel):
+    url = models.URLField()
+    tags = GenericRelation(TaggedItem)