Fix broken nested fields

4 files changed, 55 insertions, 31 deletions

diff --git a/rest_framework/compat.py b/rest_framework/compat.py
index 09b76368..d4901437 100644
--- a/rest_framework/compat.py
+++ b/rest_framework/compat.py
@@ -19,6 +19,16 @@ except ImportError:
     import StringIO
 
 
+# Try to import PIL in either of the two ways it can end up installed.
+try:
+    from PIL import Image
+except ImportError:
+    try:
+        import Image
+    except ImportError:
+        Image = None
+
+
 def get_concrete_model(model_cls):
     try:
         return model_cls._meta.concrete_model
diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index 82745973..75ce1b9f 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -1056,11 +1056,8 @@ class ImageField(FileField):
         if f is None:
             return None
 
-        # Try to import PIL in either of the two ways it can end up installed.
-        try:
-            from PIL import Image
-        except ImportError:
-            import Image
+        from compat import Image
+        assert Image is not None, 'PIL must be installed for ImageField support'
 
         # We need to get a file object for PIL. We might have a path or we might
         # have to read the data into memory.
diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index c3f260c7..ebeb43e8 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -237,7 +237,8 @@ class BaseSerializer(Field):
             except ValidationError as err:
                 self._errors[field_name] = self._errors.get(field_name, []) + list(err.messages)
 
-        # We don't run .validate() because field-validation failed and thus `attrs` may not be complete.
+        # If there are already errors, we don't run .validate() because
+        # field-validation failed and thus `attrs` may not be complete.
         # which in turn can cause inconsistent validation errors.
         if not self._errors:
             try:
@@ -299,17 +300,14 @@ class BaseSerializer(Field):
         Override default so that we can apply ModelSerializer as a nested
         field to relationships.
         """
-
         if self.source:
-            value = obj
             for component in self.source.split('.'):
-                value = getattr(value, component)
-                if is_simple_callable(value):
-                    value = value()
-            obj = value
+                obj = getattr(obj, component)
+                if is_simple_callable(obj):
+                    obj = obj()
         else:
-            value = getattr(obj, field_name)
-            if is_simple_callable(value):
+            obj = getattr(obj, field_name)
+            if is_simple_callable(obj):
                 obj = value()
 
         # If the object has an "all" method, assume it's a relationship
@@ -486,15 +484,10 @@ class ModelSerializer(Serializer):
         except KeyError:
             return ModelField(model_field=model_field, **kwargs)
 
-    def validate(self, attrs):
-        copied_attrs = copy.deepcopy(attrs)
-        restored_object = self.restore_object(copied_attrs, instance=getattr(self, 'object', None))
-        self.perform_model_validation(restored_object)
-        return attrs
-
-    def perform_model_validation(self, restored_object):
-        # Call Django's full_clean() which in turn calls: Model.clean_fields(), Model.clean(), Model.validat_unique()
-        restored_object.full_clean(exclude=list(self.get_excluded_fieldnames()))
+    # def validate(self, attrs):
+    #     restored_object = self.restore_object(attrs, instance=getattr(self, 'object', None))
+    #     restored_object.full_clean(exclude=list(self.get_excluded_fieldnames()))
+    #     return attrs
 
     def restore_object(self, attrs, instance=None):
         """
@@ -517,7 +510,14 @@ class ModelSerializer(Serializer):
         for field in self.opts.model._meta.many_to_many:
             if field.name in attrs:
                 self.m2m_data[field.name] = attrs.pop(field.name)
-        return self.opts.model(**attrs)
+
+        instance = self.opts.model(**attrs)
+        try:
+            instance.full_clean(exclude=list(self.get_excluded_fieldnames()))
+        except ValidationError, err:
+            self._errors = err.message_dict
+            return None
+        return instance
 
     def save(self, save_m2m=True):
         """
diff --git a/rest_framework/tests/serializer.py b/rest_framework/tests/serializer.py
index f80762f0..50a5f5a4 100644
--- a/rest_framework/tests/serializer.py
+++ b/rest_framework/tests/serializer.py
@@ -1,4 +1,5 @@
-import datetime, pickle
+import datetime
+import pickle
 from django.test import TestCase
 from rest_framework import serializers
 from rest_framework.tests.models import (Album, ActionItem, Anchor, BasicModel,
@@ -727,23 +728,39 @@ class SerializerPickleTests(TestCase):
                 fields = ('name', 'age')
         pickle.dumps(InnerPersonSerializer(Person(name="Noah", age=950)).data)
 
+
 class DepthTest(TestCase):
-    def test_depth(self):
-        user = Person.objects.create(name="django",age=1)
-        post = BlogPost.objects.create(title="Test blog post", writer=user)
+    def test_implicit_nesting(self):
+        writer = Person.objects.create(name="django", age=1)
+        post = BlogPost.objects.create(title="Test blog post", writer=writer)
+
+        class BlogPostSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = BlogPost
+                depth = 1
+
+        serializer = BlogPostSerializer(instance=post)
+        expected = {'id': 1, 'title': u'Test blog post',
+                    'writer': {'id': 1, 'name': u'django', 'age': 1}}
+
+        self.assertEqual(serializer.data, expected)
+
+    def test_explicit_nesting(self):
+        writer = Person.objects.create(name="django", age=1)
+        post = BlogPost.objects.create(title="Test blog post", writer=writer)
 
         class PersonSerializer(serializers.ModelSerializer):
             class Meta:
                 model = Person
-                fields = ("name", "age")
 
         class BlogPostSerializer(serializers.ModelSerializer):
+            writer = PersonSerializer()
+
             class Meta:
                 model = BlogPost
-                depth = 1
 
         serializer = BlogPostSerializer(instance=post)
         expected = {'id': 1, 'title': u'Test blog post',
-                    'writer': {'id': 1, 'name': u'django', 'age':1}}
+                    'writer': {'id': 1, 'name': u'django', 'age': 1}}
 
         self.assertEqual(serializer.data, expected)