One-to-one writable, nested serializer support

3 files changed, 160 insertions, 13 deletions

diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index f83451d3..893db2ec 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -26,13 +26,17 @@ class NestedValidationError(ValidationError):
     if the messages are a list of error messages.
 
     In the case of nested serializers, where the parent has many children,
-    then the child's `serializer.errors` will be a list of dicts.
+    then the child's `serializer.errors` will be a list of dicts.  In the case
+    of a single child, the `serializer.errors` will be a dict.
 
     We need to override the default behavior to get properly nested error dicts.
     """
 
     def __init__(self, message):
-        self.messages = message
+        if isinstance(message, dict):
+            self.messages = [message]
+        else:
+            self.messages = message
 
 
 class DictWithMetadata(dict):
@@ -143,6 +147,7 @@ class BaseSerializer(WritableField):
         self._data = None
         self._files = None
         self._errors = None
+        self._delete = False
 
     #####
     # Methods to determine which fields to use when (de)serializing objects.
@@ -354,15 +359,19 @@ class BaseSerializer(WritableField):
                 raise ValidationError(self.error_messages['required'])
             return
 
-        if self.parent.object:
-            # Set the serializer object if it exists
-            obj = getattr(self.parent.object, field_name)
-            self.object = obj
+        # Set the serializer object if it exists
+        obj = getattr(self.parent.object, field_name) if self.parent.object else None
 
         if value in (None, ''):
-            into[(self.source or field_name)] = None
+            if isinstance(self, ModelSerializer):
+                self._delete = True
+                self.object = obj
+                into[(self.source or field_name)] = self
+            else:
+                into[(self.source or field_name)] = None
         else:
             kwargs = {
+                'instance': obj,
                 'data': value,
                 'context': self.context,
                 'partial': self.partial,
@@ -371,8 +380,10 @@ class BaseSerializer(WritableField):
             serializer = self.__class__(**kwargs)
 
             if serializer.is_valid():
-                self.object = serializer.object
-                into[self.source or field_name] = serializer.object
+                if isinstance(serializer, ModelSerializer):
+                    into[self.source or field_name] = serializer
+                else:
+                    into[self.source or field_name] = serializer.object
             else:
                 # Propagate errors up to our parent
                 raise NestedValidationError(serializer.errors)
@@ -664,10 +675,17 @@ class ModelSerializer(Serializer):
         if instance:
             return self.full_clean(instance)
 
-    def save_object(self, obj):
+    def save_object(self, obj, parent=None, fk_field=None):
         """
         Save the deserialized object and return it.
         """
+        if self._delete:
+            obj.delete()
+            return
+
+        if parent and fk_field:
+            setattr(self.object, fk_field, parent)
+
         obj.save()
 
         if getattr(self, 'm2m_data', None):
@@ -677,7 +695,11 @@ class ModelSerializer(Serializer):
 
         if getattr(self, 'related_data', None):
             for accessor_name, object_list in self.related_data.items():
-                setattr(self.object, accessor_name, object_list)
+                if isinstance(object_list, ModelSerializer):
+                    fk_field = self.object._meta.get_field_by_name(accessor_name)[0].field.name
+                    object_list.save_object(object_list.object, parent=self.object, fk_field=fk_field)
+                else:
+                    setattr(self.object, accessor_name, object_list)
             self.related_data = {}
 
 
diff --git a/rest_framework/tests/nesting.py b/rest_framework/tests/nesting.py
new file mode 100644
index 00000000..35b7a365
--- /dev/null
+++ b/rest_framework/tests/nesting.py
@@ -0,0 +1,125 @@
+from __future__ import unicode_literals
+from django.db import models
+from django.test import TestCase
+from rest_framework import serializers
+
+
+class OneToOneTarget(models.Model):
+    name = models.CharField(max_length=100)
+
+
+class OneToOneTargetSource(models.Model):
+    name = models.CharField(max_length=100)
+    target = models.OneToOneField(OneToOneTarget, null=True, blank=True,
+                                  related_name='target_source')
+
+
+class OneToOneSource(models.Model):
+    name = models.CharField(max_length=100)
+    target_source = models.OneToOneField(OneToOneTargetSource, related_name='source')
+
+
+class OneToOneSourceSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = OneToOneSource
+        exclude = ('target_source', )
+
+
+class OneToOneTargetSourceSerializer(serializers.ModelSerializer):
+    source = OneToOneSourceSerializer()
+
+    class Meta:
+        model = OneToOneTargetSource
+        exclude = ('target', )
+
+class OneToOneTargetSerializer(serializers.ModelSerializer):
+    target_source = OneToOneTargetSourceSerializer()
+
+    class Meta:
+        model = OneToOneTarget
+
+
+class NestedOneToOneTests(TestCase):
+    def setUp(self):
+        for idx in range(1, 4):
+            target = OneToOneTarget(name='target-%d' % idx)
+            target.save()
+            target_source = OneToOneTargetSource(name='target-source-%d' % idx, target=target)
+            target_source.save()
+            source = OneToOneSource(name='source-%d' % idx, target_source=target_source)
+            source.save()
+
+    def test_one_to_one_retrieve(self):
+        queryset = OneToOneTarget.objects.all()
+        serializer = OneToOneTargetSerializer(queryset)
+        expected = [
+            {'id': 1, 'name': 'target-1', 'target_source': {'id': 1, 'name': 'target-source-1', 'source': {'id': 1, 'name': 'source-1'}}},
+            {'id': 2, 'name': 'target-2', 'target_source': {'id': 2, 'name': 'target-source-2', 'source': {'id': 2, 'name': 'source-2'}}},
+            {'id': 3, 'name': 'target-3', 'target_source': {'id': 3, 'name': 'target-source-3', 'source': {'id': 3, 'name': 'source-3'}}}            
+        ]
+        self.assertEqual(serializer.data, expected)
+        
+
+    def test_one_to_one_create(self):
+        data = {'id': 4, 'name': 'target-4', 'target_source': {'id': 4, 'name': 'target-source-4', 'source': {'id': 4, 'name': 'source-4'}}}
+        serializer = OneToOneTargetSerializer(data=data)
+        self.assertTrue(serializer.is_valid())
+        obj = serializer.save()
+        self.assertEqual(serializer.data, data)
+        self.assertEqual(obj.name, 'target-4')
+
+        # Ensure (target 4, target_source 4, source 4) are added, and
+        # everything else is as expected.
+        queryset = OneToOneTarget.objects.all()
+        serializer = OneToOneTargetSerializer(queryset)
+        expected = [
+            {'id': 1, 'name': 'target-1', 'target_source': {'id': 1, 'name': 'target-source-1', 'source': {'id': 1, 'name': 'source-1'}}},
+            {'id': 2, 'name': 'target-2', 'target_source': {'id': 2, 'name': 'target-source-2', 'source': {'id': 2, 'name': 'source-2'}}},
+            {'id': 3, 'name': 'target-3', 'target_source': {'id': 3, 'name': 'target-source-3', 'source': {'id': 3, 'name': 'source-3'}}},
+            {'id': 4, 'name': 'target-4', 'target_source': {'id': 4, 'name': 'target-source-4', 'source': {'id': 4, 'name': 'source-4'}}}
+        ]
+        self.assertEqual(serializer.data, expected)
+
+    def test_one_to_one_create_with_invalid_data(self):
+        data = {'id': 4, 'name': 'target-4', 'target_source': {'id': 4, 'name': 'target-source-4', 'source': {'id': 4}}}
+        serializer = OneToOneTargetSerializer(data=data)
+        self.assertFalse(serializer.is_valid())
+        self.assertEqual(serializer.errors, {'target_source': [{'source': [{'name': ['This field is required.']}]}]})
+
+    def test_one_to_one_update(self):
+        data = {'id': 3, 'name': 'target-3-updated', 'target_source': {'id': 3, 'name': 'target-source-3-updated', 'source': {'id': 3, 'name': 'source-3-updated'}}}
+        instance = OneToOneTarget.objects.get(pk=3)
+        serializer = OneToOneTargetSerializer(instance, data=data)
+        self.assertTrue(serializer.is_valid())
+        obj = serializer.save()
+        self.assertEqual(serializer.data, data)
+        self.assertEqual(obj.name, 'target-3-updated')
+
+        # Ensure (target 3, target_source 3, source 3) are updated,
+        # and everything else is as expected.
+        queryset = OneToOneTarget.objects.all()
+        serializer = OneToOneTargetSerializer(queryset)
+        expected = [
+            {'id': 1, 'name': 'target-1', 'target_source': {'id': 1, 'name': 'target-source-1', 'source': {'id': 1, 'name': 'source-1'}}},
+            {'id': 2, 'name': 'target-2', 'target_source': {'id': 2, 'name': 'target-source-2', 'source': {'id': 2, 'name': 'source-2'}}},
+            {'id': 3, 'name': 'target-3-updated', 'target_source': {'id': 3, 'name': 'target-source-3-updated', 'source': {'id': 3, 'name': 'source-3-updated'}}}
+        ]
+        self.assertEqual(serializer.data, expected)
+
+    def test_one_to_one_delete(self):
+        data = {'id': 3, 'name': 'target-3', 'target_source': None}
+        instance = OneToOneTarget.objects.get(pk=3)
+        serializer = OneToOneTargetSerializer(instance, data=data)
+        self.assertTrue(serializer.is_valid())
+        obj = serializer.save()
+
+        # Ensure (target_source 3, source 3) are deleted,
+        # and everything else is as expected.
+        queryset = OneToOneTarget.objects.all()
+        serializer = OneToOneTargetSerializer(queryset)
+        expected = [
+            {'id': 1, 'name': 'target-1', 'target_source': {'id': 1, 'name': 'target-source-1', 'source': {'id': 1, 'name': 'source-1'}}},
+            {'id': 2, 'name': 'target-2', 'target_source': {'id': 2, 'name': 'target-source-2', 'source': {'id': 2, 'name': 'source-2'}}},
+            {'id': 3, 'name': 'target-3', 'target_source': None}
+        ]
+        self.assertEqual(serializer.data, expected)
diff --git a/rest_framework/tests/serializer_nested.py b/rest_framework/tests/serializer_nested.py
index fcf644c7..299c3bc5 100644
--- a/rest_framework/tests/serializer_nested.py
+++ b/rest_framework/tests/serializer_nested.py
@@ -124,7 +124,7 @@ class WritableNestedSerializerObjectTests(TestCase):
             def __init__(self, order, title, duration):
                 self.order, self.title, self.duration = order, title, duration
 
-            def __cmp__(self, other):
+            def __eq__(self, other):
                 return (
                     self.order == other.order and
                     self.title == other.title and
@@ -135,7 +135,7 @@ class WritableNestedSerializerObjectTests(TestCase):
             def __init__(self, album_name, artist, tracks):
                 self.album_name, self.artist, self.tracks = album_name, artist, tracks
 
-            def __cmp__(self, other):
+            def __eq__(self, other):
                 return (
                     self.album_name == other.album_name and
                     self.artist == other.artist and