From 3f79a9a3d3e7692d90476f8a6907957b47aab821 Mon Sep 17 00:00:00 2001
From: Tom Christie <tom@tomchristie.com>
Date: Fri, 22 Mar 2013 22:39:45 +0000
Subject: [PATCH 01/13] one-one writable nested modelserializers

---
 rest_framework/serializers.py            |  11 +-
 rest_framework/tests/relations_nested.py | 190 ++++++++++++-----------
 2 files changed, 110 insertions(+), 91 deletions(-)

diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 6aca2f574..26c34044c 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -753,7 +753,16 @@ class ModelSerializer(Serializer):
 
         if getattr(obj, '_related_data', None):
             for accessor_name, related in obj._related_data.items():
-                setattr(obj, accessor_name, related)
+                if related is None:
+                    previous = getattr(obj, accessor_name, related)
+                    if previous:
+                        previous.delete()
+                elif isinstance(related, models.Model):
+                    fk_field = obj._meta.get_field_by_name(accessor_name)[0].field.name
+                    setattr(related, fk_field, obj)
+                    self.save_object(related)
+                else:
+                    setattr(obj, accessor_name, related)
             del(obj._related_data)
 
 
diff --git a/rest_framework/tests/relations_nested.py b/rest_framework/tests/relations_nested.py
index a125ba656..4592e5593 100644
--- a/rest_framework/tests/relations_nested.py
+++ b/rest_framework/tests/relations_nested.py
@@ -1,115 +1,125 @@
 from __future__ import unicode_literals
+from django.db import models
 from django.test import TestCase
 from rest_framework import serializers
-from rest_framework.tests.models import ForeignKeyTarget, ForeignKeySource, NullableForeignKeySource, OneToOneTarget, NullableOneToOneSource
 
 
-class ForeignKeySourceSerializer(serializers.ModelSerializer):
+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:
-        depth = 1
-        model = ForeignKeySource
+        model = OneToOneSource
+        exclude = ('target_source', )
 
 
-class FlatForeignKeySourceSerializer(serializers.ModelSerializer):
-    class Meta:
-        model = ForeignKeySource
-
-
-class ForeignKeyTargetSerializer(serializers.ModelSerializer):
-    sources = FlatForeignKeySourceSerializer(many=True)
+class OneToOneTargetSourceSerializer(serializers.ModelSerializer):
+    source = OneToOneSourceSerializer()
 
     class Meta:
-        model = ForeignKeyTarget
+        model = OneToOneTargetSource
+        exclude = ('target', )
 
 
-class NullableForeignKeySourceSerializer(serializers.ModelSerializer):
-    class Meta:
-        depth = 1
-        model = NullableForeignKeySource
-
-
-class NullableOneToOneSourceSerializer(serializers.ModelSerializer):
-    class Meta:
-        model = NullableOneToOneSource
-
-
-class NullableOneToOneTargetSerializer(serializers.ModelSerializer):
-    nullable_source = NullableOneToOneSourceSerializer()
+class OneToOneTargetSerializer(serializers.ModelSerializer):
+    target_source = OneToOneTargetSourceSerializer()
 
     class Meta:
         model = OneToOneTarget
 
 
-class ReverseForeignKeyTests(TestCase):
+class NestedOneToOneTests(TestCase):
     def setUp(self):
-        target = ForeignKeyTarget(name='target-1')
-        target.save()
-        new_target = ForeignKeyTarget(name='target-2')
-        new_target.save()
         for idx in range(1, 4):
-            source = ForeignKeySource(name='source-%d' % idx, target=target)
+            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_foreign_key_retrieve(self):
-        queryset = ForeignKeySource.objects.all()
-        serializer = ForeignKeySourceSerializer(queryset, many=True)
-        expected = [
-            {'id': 1, 'name': 'source-1', 'target': {'id': 1, 'name': 'target-1'}},
-            {'id': 2, 'name': 'source-2', 'target': {'id': 1, 'name': 'target-1'}},
-            {'id': 3, 'name': 'source-3', 'target': {'id': 1, 'name': 'target-1'}},
-        ]
-        self.assertEqual(serializer.data, expected)
-
-    def test_reverse_foreign_key_retrieve(self):
-        queryset = ForeignKeyTarget.objects.all()
-        serializer = ForeignKeyTargetSerializer(queryset, many=True)
-        expected = [
-            {'id': 1, 'name': 'target-1', 'sources': [
-                {'id': 1, 'name': 'source-1', 'target': 1},
-                {'id': 2, 'name': 'source-2', 'target': 1},
-                {'id': 3, 'name': 'source-3', 'target': 1},
-            ]},
-            {'id': 2, 'name': 'target-2', 'sources': [
-            ]}
-        ]
-        self.assertEqual(serializer.data, expected)
-
-
-class NestedNullableForeignKeyTests(TestCase):
-    def setUp(self):
-        target = ForeignKeyTarget(name='target-1')
-        target.save()
-        for idx in range(1, 4):
-            if idx == 3:
-                target = None
-            source = NullableForeignKeySource(name='source-%d' % idx, target=target)
-            source.save()
-
-    def test_foreign_key_retrieve_with_null(self):
-        queryset = NullableForeignKeySource.objects.all()
-        serializer = NullableForeignKeySourceSerializer(queryset, many=True)
-        expected = [
-            {'id': 1, 'name': 'source-1', 'target': {'id': 1, 'name': 'target-1'}},
-            {'id': 2, 'name': 'source-2', 'target': {'id': 1, 'name': 'target-1'}},
-            {'id': 3, 'name': 'source-3', 'target': None},
-        ]
-        self.assertEqual(serializer.data, expected)
-
-
-class NestedNullableOneToOneTests(TestCase):
-    def setUp(self):
-        target = OneToOneTarget(name='target-1')
-        target.save()
-        new_target = OneToOneTarget(name='target-2')
-        new_target.save()
-        source = NullableOneToOneSource(name='source-1', target=target)
-        source.save()
-
-    def test_reverse_foreign_key_retrieve_with_null(self):
+    def test_one_to_one_retrieve(self):
         queryset = OneToOneTarget.objects.all()
-        serializer = NullableOneToOneTargetSerializer(queryset, many=True)
+        serializer = OneToOneTargetSerializer(queryset)
         expected = [
-            {'id': 1, 'name': 'target-1', 'nullable_source': {'id': 1, 'name': 'source-1', 'target': 1}},
-            {'id': 2, 'name': 'target-2', 'nullable_source': None},
+            {'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())
+        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)

From d97e72cdb2f4fcc5aa2c19527a2b2ff11cf784bb Mon Sep 17 00:00:00 2001
From: Tom Christie <tom@tomchristie.com>
Date: Mon, 25 Mar 2013 17:28:23 +0000
Subject: [PATCH 02/13] Cleanup one-one nested tests and implementation

---
 rest_framework/serializers.py            |  37 ++++-
 rest_framework/tests/relations_nested.py | 194 +++++++++++++++--------
 2 files changed, 161 insertions(+), 70 deletions(-)

diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 26c34044c..668bcc49d 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -667,9 +667,12 @@ class ModelSerializer(Serializer):
         cls = self.opts.model
         opts = get_concrete_model(cls)._meta
         exclusions = [field.name for field in opts.fields + opts.many_to_many]
+
         for field_name, field in self.fields.items():
             field_name = field.source or field_name
-            if field_name in exclusions and not field.read_only:
+            if field_name in exclusions \
+                and not field.read_only \
+                and not isinstance(field, Serializer):
                 exclusions.remove(field_name)
         return exclusions
 
@@ -695,6 +698,7 @@ class ModelSerializer(Serializer):
         """
         m2m_data = {}
         related_data = {}
+        nested_forward_relations = {}
         meta = self.opts.model._meta
 
         # Reverse fk or one-to-one relations
@@ -714,6 +718,12 @@ class ModelSerializer(Serializer):
             if field.name in attrs:
                 m2m_data[field.name] = attrs.pop(field.name)
 
+        # Nested forward relations - These need to be marked so we can save
+        # them before saving the parent model instance.
+        for field_name in attrs.keys():
+            if isinstance(self.fields.get(field_name, None), Serializer):
+                nested_forward_relations[field_name] = attrs[field_name]
+
         # Update an existing instance...
         if instance is not None:
             for key, val in attrs.items():
@@ -729,6 +739,7 @@ class ModelSerializer(Serializer):
         # at the point of save.
         instance._related_data = related_data
         instance._m2m_data = m2m_data
+        instance._nested_forward_relations = nested_forward_relations
 
         return instance
 
@@ -744,6 +755,13 @@ class ModelSerializer(Serializer):
         """
         Save the deserialized object and return it.
         """
+        if getattr(obj, '_nested_forward_relations', None):
+            # Nested relationships need to be saved before we can save the
+            # parent instance.
+            for field_name, sub_object in obj._nested_forward_relations.items():
+                self.save_object(sub_object)
+                setattr(obj, field_name, sub_object)
+
         obj.save(**kwargs)
 
         if getattr(obj, '_m2m_data', None):
@@ -753,15 +771,22 @@ class ModelSerializer(Serializer):
 
         if getattr(obj, '_related_data', None):
             for accessor_name, related in obj._related_data.items():
-                if related is None:
-                    previous = getattr(obj, accessor_name, related)
-                    if previous:
-                        previous.delete()
-                elif isinstance(related, models.Model):
+                field = self.fields.get(accessor_name, None)
+                if isinstance(field, Serializer):
+                    # TODO: Following will be needed for reverse FK
+                    # if field.many:
+                    #     # Nested reverse fk relationship
+                    #     for related_item in related:
+                    #         fk_field = obj._meta.get_field_by_name(accessor_name)[0].field.name
+                    #         setattr(related_item, fk_field, obj)
+                    #         self.save_object(related_item)
+                    # else:
+                    # Nested reverse one-one relationship
                     fk_field = obj._meta.get_field_by_name(accessor_name)[0].field.name
                     setattr(related, fk_field, obj)
                     self.save_object(related)
                 else:
+                    # Reverse FK or reverse one-one
                     setattr(obj, accessor_name, related)
             del(obj._related_data)
 
diff --git a/rest_framework/tests/relations_nested.py b/rest_framework/tests/relations_nested.py
index 4592e5593..e7af65651 100644
--- a/rest_framework/tests/relations_nested.py
+++ b/rest_framework/tests/relations_nested.py
@@ -8,61 +8,46 @@ 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')
+    target = models.OneToOneField(OneToOneTarget, 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):
+class ReverseNestedOneToOneTests(TestCase):
     def setUp(self):
+        class OneToOneSourceSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = OneToOneSource
+                fields = ('id', 'name')
+
+        class OneToOneTargetSerializer(serializers.ModelSerializer):
+            source = OneToOneSourceSerializer()
+
+            class Meta:
+                model = OneToOneTarget
+                fields = ('id', 'name', 'source')
+
+        self.Serializer = OneToOneTargetSerializer
+
         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 = OneToOneSource(name='source-%d' % idx, target=target)
             source.save()
 
     def test_one_to_one_retrieve(self):
         queryset = OneToOneTarget.objects.all()
-        serializer = OneToOneTargetSerializer(queryset)
+        serializer = self.Serializer(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': 1, 'name': 'target-1', 'source': {'id': 1, 'name': 'source-1'}},
+            {'id': 2, 'name': 'target-2', 'source': {'id': 2, 'name': 'source-2'}},
+            {'id': 3, 'name': 'target-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)
+        data = {'id': 4, 'name': 'target-4', 'source': {'id': 4, 'name': 'source-4'}}
+        serializer = self.Serializer(data=data)
         self.assertTrue(serializer.is_valid())
         obj = serializer.save()
         self.assertEqual(serializer.data, data)
@@ -71,25 +56,25 @@ class NestedOneToOneTests(TestCase):
         # Ensure (target 4, target_source 4, source 4) are added, and
         # everything else is as expected.
         queryset = OneToOneTarget.objects.all()
-        serializer = OneToOneTargetSerializer(queryset)
+        serializer = self.Serializer(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'}}}
+            {'id': 1, 'name': 'target-1', 'source': {'id': 1, 'name': 'source-1'}},
+            {'id': 2, 'name': 'target-2', 'source': {'id': 2, 'name': 'source-2'}},
+            {'id': 3, 'name': 'target-3', 'source': {'id': 3, 'name': 'source-3'}},
+            {'id': 4, 'name': 'target-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)
+        data = {'id': 4, 'name': 'target-4', 'source': {'id': 4}}
+        serializer = self.Serializer(data=data)
         self.assertFalse(serializer.is_valid())
-        self.assertEqual(serializer.errors, {'target_source': [{'source': [{'name': ['This field is required.']}]}]})
+        self.assertEqual(serializer.errors, {'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'}}}
+        data = {'id': 3, 'name': 'target-3-updated', 'source': {'id': 3, 'name': 'source-3-updated'}}
         instance = OneToOneTarget.objects.get(pk=3)
-        serializer = OneToOneTargetSerializer(instance, data=data)
+        serializer = self.Serializer(instance, data=data)
         self.assertTrue(serializer.is_valid())
         obj = serializer.save()
         self.assertEqual(serializer.data, data)
@@ -98,28 +83,109 @@ class NestedOneToOneTests(TestCase):
         # Ensure (target 3, target_source 3, source 3) are updated,
         # and everything else is as expected.
         queryset = OneToOneTarget.objects.all()
-        serializer = OneToOneTargetSerializer(queryset)
+        serializer = self.Serializer(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'}}}
+            {'id': 1, 'name': 'target-1', 'source': {'id': 1, 'name': 'source-1'}},
+            {'id': 2, 'name': 'target-2', 'source': {'id': 2, 'name': 'source-2'}},
+            {'id': 3, 'name': 'target-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)
+
+class ForwardNestedOneToOneTests(TestCase):
+    def setUp(self):
+        class OneToOneTargetSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = OneToOneTarget
+                fields = ('id', 'name')
+
+        class OneToOneSourceSerializer(serializers.ModelSerializer):
+            target = OneToOneTargetSerializer()
+
+            class Meta:
+                model = OneToOneSource
+                fields = ('id', 'name', 'target')
+
+        self.Serializer = OneToOneSourceSerializer
+
+        for idx in range(1, 4):
+            target = OneToOneTarget(name='target-%d' % idx)
+            target.save()
+            source = OneToOneSource(name='source-%d' % idx, target=target)
+            source.save()
+
+    def test_one_to_one_retrieve(self):
+        queryset = OneToOneSource.objects.all()
+        serializer = self.Serializer(queryset)
+        expected = [
+            {'id': 1, 'name': 'source-1', 'target': {'id': 1, 'name': 'target-1'}},
+            {'id': 2, 'name': 'source-2', 'target': {'id': 2, 'name': 'target-2'}},
+            {'id': 3, 'name': 'source-3', 'target': {'id': 3, 'name': 'target-3'}}
+        ]
+        self.assertEqual(serializer.data, expected)
+
+    def test_one_to_one_create(self):
+        data = {'id': 4, 'name': 'source-4', 'target': {'id': 4, 'name': 'target-4'}}
+        serializer = self.Serializer(data=data)
         self.assertTrue(serializer.is_valid())
-        serializer.save()
+        obj = serializer.save()
+        self.assertEqual(serializer.data, data)
+        self.assertEqual(obj.name, 'source-4')
 
-        # Ensure (target_source 3, source 3) are deleted,
-        # and everything else is as expected.
-        queryset = OneToOneTarget.objects.all()
-        serializer = OneToOneTargetSerializer(queryset)
+        # Ensure (target 4, target_source 4, source 4) are added, and
+        # everything else is as expected.
+        queryset = OneToOneSource.objects.all()
+        serializer = self.Serializer(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}
+            {'id': 1, 'name': 'source-1', 'target': {'id': 1, 'name': 'target-1'}},
+            {'id': 2, 'name': 'source-2', 'target': {'id': 2, 'name': 'target-2'}},
+            {'id': 3, 'name': 'source-3', 'target': {'id': 3, 'name': 'target-3'}},
+            {'id': 4, 'name': 'source-4', 'target': {'id': 4, 'name': 'target-4'}}
         ]
         self.assertEqual(serializer.data, expected)
+
+    def test_one_to_one_create_with_invalid_data(self):
+        data = {'id': 4, 'name': 'source-4', 'target': {'id': 4}}
+        serializer = self.Serializer(data=data)
+        self.assertFalse(serializer.is_valid())
+        self.assertEqual(serializer.errors, {'target': [{'name': ['This field is required.']}]})
+
+    def test_one_to_one_update(self):
+        data = {'id': 3, 'name': 'source-3-updated', 'target': {'id': 3, 'name': 'target-3-updated'}}
+        instance = OneToOneSource.objects.get(pk=3)
+        serializer = self.Serializer(instance, data=data)
+        self.assertTrue(serializer.is_valid())
+        obj = serializer.save()
+        self.assertEqual(serializer.data, data)
+        self.assertEqual(obj.name, 'source-3-updated')
+
+        # Ensure (target 3, target_source 3, source 3) are updated,
+        # and everything else is as expected.
+        queryset = OneToOneSource.objects.all()
+        serializer = self.Serializer(queryset)
+        expected = [
+            {'id': 1, 'name': 'source-1', 'target': {'id': 1, 'name': 'target-1'}},
+            {'id': 2, 'name': 'source-2', 'target': {'id': 2, 'name': 'target-2'}},
+            {'id': 3, 'name': 'source-3-updated', 'target': {'id': 3, 'name': 'target-3-updated'}}
+        ]
+        self.assertEqual(serializer.data, expected)
+
+
+    # TODO: Nullable 1-1 tests
+    # def test_one_to_one_delete(self):
+    #     data = {'id': 3, 'name': 'target-3', 'target_source': None}
+    #     instance = OneToOneTarget.objects.get(pk=3)
+    #     serializer = self.Serializer(instance, data=data)
+    #     self.assertTrue(serializer.is_valid())
+    #     serializer.save()
+
+    #     # Ensure (target_source 3, source 3) are deleted,
+    #     # and everything else is as expected.
+    #     queryset = OneToOneTarget.objects.all()
+    #     serializer = self.Serializer(queryset)
+    #     expected = [
+    #         {'id': 1, 'name': 'target-1', 'source': {'id': 1, 'name': 'source-1'}},
+    #         {'id': 2, 'name': 'target-2', 'source': {'id': 2, 'name': 'source-2'}},
+    #         {'id': 3, 'name': 'target-3', 'source': None}
+    #     ]
+    #     self.assertEqual(serializer.data, expected)

From 73efa96de983fc644328d2fc498651aa917a2272 Mon Sep 17 00:00:00 2001
From: Mark Aaron Shirley <maspwr@gmail.com>
Date: Sat, 6 Apr 2013 08:43:21 -0700
Subject: [PATCH 03/13] one-many writable nested modelserializer support

---
 rest_framework/serializers.py                 | 56 +++++++----
 rest_framework/tests/relations_nested.py      | 98 +++++++++++++++++++
 .../tests/serializer_bulk_update.py           |  6 +-
 3 files changed, 139 insertions(+), 21 deletions(-)

diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 668bcc49d..73cad00f6 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -130,14 +130,14 @@ class BaseSerializer(WritableField):
 
     def __init__(self, instance=None, data=None, files=None,
                  context=None, partial=False, many=None,
-                 allow_delete=False, **kwargs):
+                 allow_add_remove=False, **kwargs):
         super(BaseSerializer, self).__init__(**kwargs)
         self.opts = self._options_class(self.Meta)
         self.parent = None
         self.root = None
         self.partial = partial
         self.many = many
-        self.allow_delete = allow_delete
+        self.allow_add_remove = allow_add_remove
 
         self.context = context or {}
 
@@ -154,8 +154,8 @@ class BaseSerializer(WritableField):
         if many and instance is not None and not hasattr(instance, '__iter__'):
             raise ValueError('instance should be a queryset or other iterable with many=True')
 
-        if allow_delete and not many:
-            raise ValueError('allow_delete should only be used for bulk updates, but you have not set many=True')
+        if allow_add_remove and not many:
+            raise ValueError('allow_add_remove should only be used for bulk updates, but you have not set many=True')
 
     #####
     # Methods to determine which fields to use when (de)serializing objects.
@@ -288,8 +288,15 @@ class BaseSerializer(WritableField):
         You should override this method to control how deserialized objects
         are instantiated.
         """
+        removed_relations = []
+
+        # Deleted related objects
+        if self._deleted:
+            removed_relations = list(self._deleted)
+
         if instance is not None:
             instance.update(attrs)
+            instance._removed_relations = removed_relations
             return instance
         return attrs
 
@@ -377,6 +384,7 @@ class BaseSerializer(WritableField):
 
         # Set the serializer object if it exists
         obj = getattr(self.parent.object, field_name) if self.parent.object else None
+        obj = obj.all() if is_simple_callable(getattr(obj, 'all', None)) else obj
 
         if value in (None, ''):
             into[(self.source or field_name)] = None
@@ -386,7 +394,8 @@ class BaseSerializer(WritableField):
                 'data': value,
                 'context': self.context,
                 'partial': self.partial,
-                'many': self.many
+                'many': self.many,
+                'allow_add_remove': self.allow_add_remove
             }
             serializer = self.__class__(**kwargs)
 
@@ -496,6 +505,9 @@ class BaseSerializer(WritableField):
     def save_object(self, obj, **kwargs):
         obj.save(**kwargs)
 
+        if self.allow_add_remove and hasattr(obj, '_removed_relations'):
+            [self.delete_object(item) for item in obj._removed_relations]
+
     def delete_object(self, obj):
         obj.delete()
 
@@ -508,7 +520,7 @@ class BaseSerializer(WritableField):
         else:
             self.save_object(self.object, **kwargs)
 
-        if self.allow_delete and self._deleted:
+        if self.allow_add_remove and self._deleted:
             [self.delete_object(item) for item in self._deleted]
 
         return self.object
@@ -699,6 +711,7 @@ class ModelSerializer(Serializer):
         m2m_data = {}
         related_data = {}
         nested_forward_relations = {}
+        removed_relations = []
         meta = self.opts.model._meta
 
         # Reverse fk or one-to-one relations
@@ -724,6 +737,10 @@ class ModelSerializer(Serializer):
             if isinstance(self.fields.get(field_name, None), Serializer):
                 nested_forward_relations[field_name] = attrs[field_name]
 
+        # Deleted related objects
+        if self._deleted:
+            removed_relations = list(self._deleted)
+
         # Update an existing instance...
         if instance is not None:
             for key, val in attrs.items():
@@ -740,6 +757,7 @@ class ModelSerializer(Serializer):
         instance._related_data = related_data
         instance._m2m_data = m2m_data
         instance._nested_forward_relations = nested_forward_relations
+        instance._removed_relations = removed_relations
 
         return instance
 
@@ -764,6 +782,9 @@ class ModelSerializer(Serializer):
 
         obj.save(**kwargs)
 
+        if self.allow_add_remove and hasattr(obj, '_removed_relations'):
+            [self.delete_object(item) for item in obj._removed_relations]
+
         if getattr(obj, '_m2m_data', None):
             for accessor_name, object_list in obj._m2m_data.items():
                 setattr(obj, accessor_name, object_list)
@@ -773,18 +794,17 @@ class ModelSerializer(Serializer):
             for accessor_name, related in obj._related_data.items():
                 field = self.fields.get(accessor_name, None)
                 if isinstance(field, Serializer):
-                    # TODO: Following will be needed for reverse FK
-                    # if field.many:
-                    #     # Nested reverse fk relationship
-                    #     for related_item in related:
-                    #         fk_field = obj._meta.get_field_by_name(accessor_name)[0].field.name
-                    #         setattr(related_item, fk_field, obj)
-                    #         self.save_object(related_item)
-                    # else:
-                    # Nested reverse one-one relationship
-                    fk_field = obj._meta.get_field_by_name(accessor_name)[0].field.name
-                    setattr(related, fk_field, obj)
-                    self.save_object(related)
+                    if field.many:
+                        # Nested reverse fk relationship
+                        for related_item in related:
+                            fk_field = obj._meta.get_field_by_name(accessor_name)[0].field.name
+                            setattr(related_item, fk_field, obj)
+                            self.save_object(related_item)
+                    else:
+                        # Nested reverse one-one relationship
+                        fk_field = obj._meta.get_field_by_name(accessor_name)[0].field.name
+                        setattr(related, fk_field, obj)
+                        self.save_object(related)
                 else:
                     # Reverse FK or reverse one-one
                     setattr(obj, accessor_name, related)
diff --git a/rest_framework/tests/relations_nested.py b/rest_framework/tests/relations_nested.py
index e7af65651..20683d4a6 100644
--- a/rest_framework/tests/relations_nested.py
+++ b/rest_framework/tests/relations_nested.py
@@ -13,6 +13,15 @@ class OneToOneSource(models.Model):
     target = models.OneToOneField(OneToOneTarget, related_name='source')
 
 
+class OneToManyTarget(models.Model):
+    name = models.CharField(max_length=100)
+
+
+class OneToManySource(models.Model):
+    name = models.CharField(max_length=100)
+    target = models.ForeignKey(OneToManyTarget, related_name='sources')
+
+        
 class ReverseNestedOneToOneTests(TestCase):
     def setUp(self):
         class OneToOneSourceSerializer(serializers.ModelSerializer):
@@ -189,3 +198,92 @@ class ForwardNestedOneToOneTests(TestCase):
     #         {'id': 3, 'name': 'target-3', 'source': None}
     #     ]
     #     self.assertEqual(serializer.data, expected)
+
+
+class ReverseNestedOneToManyTests(TestCase):
+    def setUp(self):
+        class OneToManySourceSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = OneToManySource
+                fields = ('id', 'name')
+
+        class OneToManyTargetSerializer(serializers.ModelSerializer):
+            sources = OneToManySourceSerializer(many=True, allow_add_remove=True)
+
+            class Meta:
+                model = OneToManyTarget
+                fields = ('id', 'name', 'sources')
+
+        self.Serializer = OneToManyTargetSerializer
+
+        target = OneToManyTarget(name='target-1')
+        target.save()
+        for idx in range(1, 4):
+            source = OneToManySource(name='source-%d' % idx, target=target)
+            source.save()
+
+    def test_one_to_many_retrieve(self):
+        queryset = OneToManyTarget.objects.all()
+        serializer = self.Serializer(queryset)
+        expected = [
+            {'id': 1, 'name': 'target-1', 'sources': [{'id': 1, 'name': 'source-1'},
+                                                      {'id': 2, 'name': 'source-2'},
+                                                      {'id': 3, 'name': 'source-3'}]},
+        ]
+        self.assertEqual(serializer.data, expected)
+
+    def test_one_to_many_create(self):
+        data = {'id': 1, 'name': 'target-1', 'sources': [{'id': 1, 'name': 'source-1'},
+                                                         {'id': 2, 'name': 'source-2'},
+                                                         {'id': 3, 'name': 'source-3'},
+                                                         {'id': 4, 'name': 'source-4'}]}
+        instance = OneToManyTarget.objects.get(pk=1)
+        serializer = self.Serializer(instance, data=data)
+        self.assertTrue(serializer.is_valid())
+        obj = serializer.save()
+        self.assertEqual(serializer.data, data)
+        self.assertEqual(obj.name, 'target-1')
+
+        # Ensure source 4 is added, and everything else is as
+        # expected.
+        queryset = OneToManyTarget.objects.all()
+        serializer = self.Serializer(queryset)
+        expected = [
+            {'id': 1, 'name': 'target-1', 'sources': [{'id': 1, 'name': 'source-1'},
+                                                      {'id': 2, 'name': 'source-2'},
+                                                      {'id': 3, 'name': 'source-3'},
+                                                      {'id': 4, 'name': 'source-4'}]}
+        ]
+        self.assertEqual(serializer.data, expected)
+
+    def test_one_to_many_create_with_invalid_data(self):
+        data = {'id': 1, 'name': 'target-1', 'sources': [{'id': 1, 'name': 'source-1'},
+                                                         {'id': 2, 'name': 'source-2'},
+                                                         {'id': 3, 'name': 'source-3'},
+                                                         {'id': 4}]}
+        serializer = self.Serializer(data=data)
+        self.assertFalse(serializer.is_valid())
+        self.assertEqual(serializer.errors, {'sources': [{}, {}, {}, {'name': ['This field is required.']}]})
+
+    def test_one_to_many_update(self):
+        data = {'id': 1, 'name': 'target-1-updated', 'sources': [{'id': 1, 'name': 'source-1-updated'},
+                                                                 {'id': 2, 'name': 'source-2'},
+                                                                 {'id': 3, 'name': 'source-3'}]}
+        instance = OneToManyTarget.objects.get(pk=1)
+        serializer = self.Serializer(instance, data=data)
+        self.assertTrue(serializer.is_valid())
+        obj = serializer.save()
+        self.assertEqual(serializer.data, data)
+        self.assertEqual(obj.name, 'target-1-updated')
+
+        # Ensure (target 1, source 1) are updated,
+        # and everything else is as expected.
+        queryset = OneToManyTarget.objects.all()
+        serializer = self.Serializer(queryset)
+        expected = [
+            {'id': 1, 'name': 'target-1-updated', 'sources': [{'id': 1, 'name': 'source-1-updated'},
+                                                              {'id': 2, 'name': 'source-2'},
+                                                              {'id': 3, 'name': 'source-3'}]}
+
+        ]
+        self.assertEqual(serializer.data, expected)
diff --git a/rest_framework/tests/serializer_bulk_update.py b/rest_framework/tests/serializer_bulk_update.py
index afc1a1a9f..5328e7331 100644
--- a/rest_framework/tests/serializer_bulk_update.py
+++ b/rest_framework/tests/serializer_bulk_update.py
@@ -201,7 +201,7 @@ class BulkUpdateSerializerTests(TestCase):
                 'author': 'Haruki Murakami'
             }
         ]
-        serializer = self.BookSerializer(self.books(), data=data, many=True, allow_delete=True)
+        serializer = self.BookSerializer(self.books(), data=data, many=True, allow_add_remove=True)
         self.assertEqual(serializer.is_valid(), True)
         self.assertEqual(serializer.data, data)
         serializer.save()
@@ -223,7 +223,7 @@ class BulkUpdateSerializerTests(TestCase):
                 'author': 'Haruki Murakami'
             }
         ]
-        serializer = self.BookSerializer(self.books(), data=data, many=True, allow_delete=True)
+        serializer = self.BookSerializer(self.books(), data=data, many=True, allow_add_remove=True)
         self.assertEqual(serializer.is_valid(), True)
         self.assertEqual(serializer.data, data)
         serializer.save()
@@ -249,6 +249,6 @@ class BulkUpdateSerializerTests(TestCase):
             {},
             {'id': ['Enter a whole number.']}
         ]
-        serializer = self.BookSerializer(self.books(), data=data, many=True, allow_delete=True)
+        serializer = self.BookSerializer(self.books(), data=data, many=True, allow_add_remove=True)
         self.assertEqual(serializer.is_valid(), False)
         self.assertEqual(serializer.errors, expected_errors)

From bda25479aa7e73c90bc77b7c7219eaa411af138e Mon Sep 17 00:00:00 2001
From: Mark Aaron Shirley <maspwr@gmail.com>
Date: Wed, 10 Apr 2013 08:44:54 -0700
Subject: [PATCH 04/13] Update docs with allow_add_remove

---
 docs/api-guide/serializers.md | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/docs/api-guide/serializers.md b/docs/api-guide/serializers.md
index 42e81cad5..aeb33916e 100644
--- a/docs/api-guide/serializers.md
+++ b/docs/api-guide/serializers.md
@@ -244,15 +244,15 @@ This allows you to write views that update or create multiple items when a `PUT`
 
 Bulk updates will update any instances that already exist, and create new instances for data items that do not have a corresponding instance.
 
-When performing a bulk update you may want any items that are not present in the incoming data to be deleted.  To do so, pass `allow_delete=True` to the serializer.
+When performing a bulk update you may want any items that are not present in the incoming data to be deleted.  To do so, pass `allow_add_remove=True` to the serializer.
 
-    serializer = BookSerializer(queryset, data=data, many=True, allow_delete=True)
+    serializer = BookSerializer(queryset, data=data, many=True, allow_add_remove=True)
     serializer.is_valid()
     # True
     serializer.save()  # `.save()` will be called on each updated or newly created instance.
                        # `.delete()` will be called on any other items in the `queryset`.
 
-Passing `allow_delete=True` ensures that any update operations will completely overwrite the existing queryset, rather than simply updating any objects found in the incoming data. 
+Passing `allow_add_remove=True` ensures that any update operations will completely overwrite the existing queryset, rather than simply updating any objects found in the incoming data. 
 
 #### How identity is determined when performing bulk updates
 

From fdc5cc3d81679d30cd20acf063dc7dc74ad17d7a Mon Sep 17 00:00:00 2001
From: Mark Aaron Shirley <maspwr@gmail.com>
Date: Thu, 18 Apr 2013 10:28:20 -0700
Subject: [PATCH 05/13] Fix model serializer nestesd delete behavior

---
 rest_framework/serializers.py            | 40 +++++++++---------------
 rest_framework/tests/relations_nested.py | 19 +++++++++++
 2 files changed, 33 insertions(+), 26 deletions(-)

diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 0f0f11a4c..78c455481 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -20,6 +20,9 @@ from rest_framework.relations import *
 from rest_framework.fields import *
 
 
+class RelationsList(list):
+    _deleted = []
+
 class NestedValidationError(ValidationError):
     """
     The default ValidationError behavior is to stringify each item in the list
@@ -149,7 +152,6 @@ class BaseSerializer(WritableField):
         self._data = None
         self._files = None
         self._errors = None
-        self._deleted = None
 
         if many and instance is not None and not hasattr(instance, '__iter__'):
             raise ValueError('instance should be a queryset or other iterable with many=True')
@@ -288,15 +290,8 @@ class BaseSerializer(WritableField):
         You should override this method to control how deserialized objects
         are instantiated.
         """
-        removed_relations = []
-
-        # Deleted related objects
-        if self._deleted:
-            removed_relations = list(self._deleted)
-
         if instance is not None:
             instance.update(attrs)
-            instance._removed_relations = removed_relations
             return instance
         return attrs
 
@@ -438,7 +433,7 @@ class BaseSerializer(WritableField):
                                   PendingDeprecationWarning, stacklevel=3)
 
             if many:
-                ret = []
+                ret = RelationsList()
                 errors = []
                 update = self.object is not None
 
@@ -466,7 +461,7 @@ class BaseSerializer(WritableField):
                         errors.append(self._errors)
 
                     if update:
-                        self._deleted = identity_to_objects.values()
+                        ret._deleted = identity_to_objects.values()
 
                     self._errors = any(errors) and errors or []
                 else:
@@ -509,9 +504,6 @@ class BaseSerializer(WritableField):
     def save_object(self, obj, **kwargs):
         obj.save(**kwargs)
 
-        if self.allow_add_remove and hasattr(obj, '_removed_relations'):
-            [self.delete_object(item) for item in obj._removed_relations]
-
     def delete_object(self, obj):
         obj.delete()
 
@@ -521,11 +513,11 @@ class BaseSerializer(WritableField):
         """
         if isinstance(self.object, list):
             [self.save_object(item, **kwargs) for item in self.object]
-        else:
-            self.save_object(self.object, **kwargs)
 
-        if self.allow_add_remove and self._deleted:
-            [self.delete_object(item) for item in self._deleted]
+            if self.allow_add_remove and self.object._deleted:
+                [self.delete_object(item) for item in self.object._deleted]
+        else:
+            self.save_object(self.object, **kwargs)        
 
         return self.object
 
@@ -715,7 +707,6 @@ class ModelSerializer(Serializer):
         m2m_data = {}
         related_data = {}
         nested_forward_relations = {}
-        removed_relations = []
         meta = self.opts.model._meta
 
         # Reverse fk or one-to-one relations
@@ -741,10 +732,6 @@ class ModelSerializer(Serializer):
             if isinstance(self.fields.get(field_name, None), Serializer):
                 nested_forward_relations[field_name] = attrs[field_name]
 
-        # Deleted related objects
-        if self._deleted:
-            removed_relations = list(self._deleted)
-
         # Update an existing instance...
         if instance is not None:
             for key, val in attrs.items():
@@ -761,7 +748,6 @@ class ModelSerializer(Serializer):
         instance._related_data = related_data
         instance._m2m_data = m2m_data
         instance._nested_forward_relations = nested_forward_relations
-        instance._removed_relations = removed_relations
 
         return instance
 
@@ -786,9 +772,6 @@ class ModelSerializer(Serializer):
 
         obj.save(**kwargs)
 
-        if self.allow_add_remove and hasattr(obj, '_removed_relations'):
-            [self.delete_object(item) for item in obj._removed_relations]
-
         if getattr(obj, '_m2m_data', None):
             for accessor_name, object_list in obj._m2m_data.items():
                 setattr(obj, accessor_name, object_list)
@@ -804,6 +787,11 @@ class ModelSerializer(Serializer):
                             fk_field = obj._meta.get_field_by_name(accessor_name)[0].field.name
                             setattr(related_item, fk_field, obj)
                             self.save_object(related_item)
+
+                        # Delete any removed objects
+                        if field.allow_add_remove and related._deleted:
+                            [self.delete_object(item) for item in related._deleted]
+
                     else:
                         # Nested reverse one-one relationship
                         fk_field = obj._meta.get_field_by_name(accessor_name)[0].field.name
diff --git a/rest_framework/tests/relations_nested.py b/rest_framework/tests/relations_nested.py
index 20683d4a6..22c98e7ff 100644
--- a/rest_framework/tests/relations_nested.py
+++ b/rest_framework/tests/relations_nested.py
@@ -287,3 +287,22 @@ class ReverseNestedOneToManyTests(TestCase):
 
         ]
         self.assertEqual(serializer.data, expected)
+
+    def test_one_to_many_delete(self):
+        data = {'id': 1, 'name': 'target-1', 'sources': [{'id': 1, 'name': 'source-1'},
+                                                         {'id': 3, 'name': 'source-3'}]}
+        instance = OneToManyTarget.objects.get(pk=1)
+        serializer = self.Serializer(instance, data=data)
+        self.assertTrue(serializer.is_valid())
+        serializer.save()
+
+        # Ensure source 2 is deleted, and everything else is as
+        # expected.
+        queryset = OneToManyTarget.objects.all()
+        serializer = self.Serializer(queryset)
+        expected = [
+            {'id': 1, 'name': 'target-1', 'sources': [{'id': 1, 'name': 'source-1'},
+                                                      {'id': 3, 'name': 'source-3'}]}
+
+        ]
+        self.assertEqual(serializer.data, expected)

From 7e0a93f0eefead25f0e9b6615675f394af3a4ba0 Mon Sep 17 00:00:00 2001
From: Mark Aaron Shirley <maspwr@gmail.com>
Date: Fri, 19 Apr 2013 10:46:57 -0700
Subject: [PATCH 06/13] Don't use field when saving related data

---
 rest_framework/serializers.py | 36 +++++++++++++++++------------------
 1 file changed, 17 insertions(+), 19 deletions(-)

diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 78c455481..b39cb8105 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -460,7 +460,7 @@ class BaseSerializer(WritableField):
                         ret.append(self.from_native(item, None))
                         errors.append(self._errors)
 
-                    if update:
+                    if update and self.allow_add_remove:
                         ret._deleted = identity_to_objects.values()
 
                     self._errors = any(errors) and errors or []
@@ -514,7 +514,7 @@ class BaseSerializer(WritableField):
         if isinstance(self.object, list):
             [self.save_object(item, **kwargs) for item in self.object]
 
-            if self.allow_add_remove and self.object._deleted:
+            if self.object._deleted:
                 [self.delete_object(item) for item in self.object._deleted]
         else:
             self.save_object(self.object, **kwargs)        
@@ -779,24 +779,22 @@ class ModelSerializer(Serializer):
 
         if getattr(obj, '_related_data', None):
             for accessor_name, related in obj._related_data.items():
-                field = self.fields.get(accessor_name, None)
-                if isinstance(field, Serializer):
-                    if field.many:
-                        # Nested reverse fk relationship
-                        for related_item in related:
-                            fk_field = obj._meta.get_field_by_name(accessor_name)[0].field.name
-                            setattr(related_item, fk_field, obj)
-                            self.save_object(related_item)
-
-                        # Delete any removed objects
-                        if field.allow_add_remove and related._deleted:
-                            [self.delete_object(item) for item in related._deleted]
-
-                    else:
-                        # Nested reverse one-one relationship
+                if isinstance(related, RelationsList):
+                    # Nested reverse fk relationship
+                    for related_item in related:
                         fk_field = obj._meta.get_field_by_name(accessor_name)[0].field.name
-                        setattr(related, fk_field, obj)
-                        self.save_object(related)
+                        setattr(related_item, fk_field, obj)
+                        self.save_object(related_item)
+
+                    # Delete any removed objects
+                    if related._deleted:
+                        [self.delete_object(item) for item in related._deleted]
+
+                elif isinstance(related, models.Model):
+                    # Nested reverse one-one relationship
+                    fk_field = obj._meta.get_field_by_name(accessor_name)[0].field.name
+                    setattr(related, fk_field, obj)
+                    self.save_object(related)
                 else:
                     # Reverse FK or reverse one-one
                     setattr(obj, accessor_name, related)

From 14482a966168a98d43099d00c163d1c8c3b6471b Mon Sep 17 00:00:00 2001
From: Mark Aaron Shirley <maspwr@gmail.com>
Date: Wed, 8 May 2013 22:44:23 -0700
Subject: [PATCH 07/13] Fix deprecation warnings in relations_nested tests

---
 rest_framework/tests/relations_nested.py | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/rest_framework/tests/relations_nested.py b/rest_framework/tests/relations_nested.py
index 22c98e7ff..8325580f6 100644
--- a/rest_framework/tests/relations_nested.py
+++ b/rest_framework/tests/relations_nested.py
@@ -46,7 +46,7 @@ class ReverseNestedOneToOneTests(TestCase):
 
     def test_one_to_one_retrieve(self):
         queryset = OneToOneTarget.objects.all()
-        serializer = self.Serializer(queryset)
+        serializer = self.Serializer(queryset, many=True)
         expected = [
             {'id': 1, 'name': 'target-1', 'source': {'id': 1, 'name': 'source-1'}},
             {'id': 2, 'name': 'target-2', 'source': {'id': 2, 'name': 'source-2'}},
@@ -65,7 +65,7 @@ class ReverseNestedOneToOneTests(TestCase):
         # Ensure (target 4, target_source 4, source 4) are added, and
         # everything else is as expected.
         queryset = OneToOneTarget.objects.all()
-        serializer = self.Serializer(queryset)
+        serializer = self.Serializer(queryset, many=True)
         expected = [
             {'id': 1, 'name': 'target-1', 'source': {'id': 1, 'name': 'source-1'}},
             {'id': 2, 'name': 'target-2', 'source': {'id': 2, 'name': 'source-2'}},
@@ -92,7 +92,7 @@ class ReverseNestedOneToOneTests(TestCase):
         # Ensure (target 3, target_source 3, source 3) are updated,
         # and everything else is as expected.
         queryset = OneToOneTarget.objects.all()
-        serializer = self.Serializer(queryset)
+        serializer = self.Serializer(queryset, many=True)
         expected = [
             {'id': 1, 'name': 'target-1', 'source': {'id': 1, 'name': 'source-1'}},
             {'id': 2, 'name': 'target-2', 'source': {'id': 2, 'name': 'source-2'}},
@@ -125,7 +125,7 @@ class ForwardNestedOneToOneTests(TestCase):
 
     def test_one_to_one_retrieve(self):
         queryset = OneToOneSource.objects.all()
-        serializer = self.Serializer(queryset)
+        serializer = self.Serializer(queryset, many=True)
         expected = [
             {'id': 1, 'name': 'source-1', 'target': {'id': 1, 'name': 'target-1'}},
             {'id': 2, 'name': 'source-2', 'target': {'id': 2, 'name': 'target-2'}},
@@ -144,7 +144,7 @@ class ForwardNestedOneToOneTests(TestCase):
         # Ensure (target 4, target_source 4, source 4) are added, and
         # everything else is as expected.
         queryset = OneToOneSource.objects.all()
-        serializer = self.Serializer(queryset)
+        serializer = self.Serializer(queryset, many=True)
         expected = [
             {'id': 1, 'name': 'source-1', 'target': {'id': 1, 'name': 'target-1'}},
             {'id': 2, 'name': 'source-2', 'target': {'id': 2, 'name': 'target-2'}},
@@ -171,7 +171,7 @@ class ForwardNestedOneToOneTests(TestCase):
         # Ensure (target 3, target_source 3, source 3) are updated,
         # and everything else is as expected.
         queryset = OneToOneSource.objects.all()
-        serializer = self.Serializer(queryset)
+        serializer = self.Serializer(queryset, many=True)
         expected = [
             {'id': 1, 'name': 'source-1', 'target': {'id': 1, 'name': 'target-1'}},
             {'id': 2, 'name': 'source-2', 'target': {'id': 2, 'name': 'target-2'}},
@@ -224,7 +224,7 @@ class ReverseNestedOneToManyTests(TestCase):
 
     def test_one_to_many_retrieve(self):
         queryset = OneToManyTarget.objects.all()
-        serializer = self.Serializer(queryset)
+        serializer = self.Serializer(queryset, many=True)
         expected = [
             {'id': 1, 'name': 'target-1', 'sources': [{'id': 1, 'name': 'source-1'},
                                                       {'id': 2, 'name': 'source-2'},
@@ -247,7 +247,7 @@ class ReverseNestedOneToManyTests(TestCase):
         # Ensure source 4 is added, and everything else is as
         # expected.
         queryset = OneToManyTarget.objects.all()
-        serializer = self.Serializer(queryset)
+        serializer = self.Serializer(queryset, many=True)
         expected = [
             {'id': 1, 'name': 'target-1', 'sources': [{'id': 1, 'name': 'source-1'},
                                                       {'id': 2, 'name': 'source-2'},
@@ -279,7 +279,7 @@ class ReverseNestedOneToManyTests(TestCase):
         # Ensure (target 1, source 1) are updated,
         # and everything else is as expected.
         queryset = OneToManyTarget.objects.all()
-        serializer = self.Serializer(queryset)
+        serializer = self.Serializer(queryset, many=True)
         expected = [
             {'id': 1, 'name': 'target-1-updated', 'sources': [{'id': 1, 'name': 'source-1-updated'},
                                                               {'id': 2, 'name': 'source-2'},
@@ -299,7 +299,7 @@ class ReverseNestedOneToManyTests(TestCase):
         # Ensure source 2 is deleted, and everything else is as
         # expected.
         queryset = OneToManyTarget.objects.all()
-        serializer = self.Serializer(queryset)
+        serializer = self.Serializer(queryset, many=True)
         expected = [
             {'id': 1, 'name': 'target-1', 'sources': [{'id': 1, 'name': 'source-1'},
                                                       {'id': 3, 'name': 'source-3'}]}

From 7815811fe3047b5110e6993ecd72349f6f232232 Mon Sep 17 00:00:00 2001
From: Mark Aaron Shirley <maspwr@gmail.com>
Date: Sun, 14 Jul 2013 18:13:37 -0700
Subject: [PATCH 08/13] Update nested serialization docs

---
 docs/api-guide/relations.md   |  2 --
 docs/api-guide/serializers.md | 17 ++++++++++-------
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/docs/api-guide/relations.md b/docs/api-guide/relations.md
index 50c9bc546..21942eeff 100644
--- a/docs/api-guide/relations.md
+++ b/docs/api-guide/relations.md
@@ -213,8 +213,6 @@ Nested relationships can be expressed by using serializers as fields.
 
 If the field is used to represent a to-many relationship, you should add the `many=True` flag to the serializer field.
 
-Note that nested relationships are currently read-only.  For read-write relationships, you should use a flat relational style.
-
 ## Example
 
 For example, the following serializer:
diff --git a/docs/api-guide/serializers.md b/docs/api-guide/serializers.md
index d9c23580c..23c999429 100644
--- a/docs/api-guide/serializers.md
+++ b/docs/api-guide/serializers.md
@@ -177,7 +177,7 @@ If a nested representation may optionally accept the `None` value you should pas
         content = serializers.CharField(max_length=200)
         created = serializers.DateTimeField()
 
-Similarly if a nested representation should be a list of items, you should the `many=True` flag to the nested serialized.
+Similarly if a nested representation should be a list of items, you should pass the `many=True` flag to the nested serialized.
 
     class CommentSerializer(serializers.Serializer):
         user = UserSerializer(required=False)
@@ -185,11 +185,13 @@ Similarly if a nested representation should be a list of items, you should the `
         content = serializers.CharField(max_length=200)
         created = serializers.DateTimeField()
 
----
+Validation of nested objects will work the same as before.  Errors with nested objects will be nested under the field name of the nested object.
 
-**Note**: Nested serializers are only suitable for read-only representations, as there are cases where they would have ambiguous or non-obvious behavior if used when updating instances.  For read-write representations you should always use a flat representation, by using one of the `RelatedField` subclasses.
-
----
+    serializer = CommentSerializer(comment, data={'user': {'email': 'foobar', 'user': 'doe'}, 'content': 'baz'})
+    serializer.is_valid()
+    # False
+    serializer.errors
+    # {'user': {'email': [u'Enter a valid e-mail address.']}, 'created': [u'This field is required.']}
 
 ## Dealing with multiple objects
 
@@ -293,8 +295,7 @@ You can provide arbitrary additional context by passing a `context` argument whe
 
 The context dictionary can be used within any serializer field logic, such as a custom `.to_native()` method, by accessing the `self.context` attribute.
 
----
-
+-
 # ModelSerializer
 
 Often you'll want serializer classes that map closely to model definitions.
@@ -331,6 +332,8 @@ The default `ModelSerializer` uses primary keys for relationships, but you can a
 
 The `depth` option should be set to an integer value that indicates the depth of relationships that should be traversed before reverting to a flat representation.
 
+If you want to customize the way the serialization is done (e.g. using `allow_add_remove`) you'll need to define the field yourself.
+
 ## Specifying which fields should be read-only 
 
 You may wish to specify multiple fields as read-only.  Instead of adding each field explicitly with the `read_only=True` attribute, you may use the `read_only_fields` Meta option, like so:

From b5dc6b61131cc36b0540133a28613c06e7f4e26a Mon Sep 17 00:00:00 2001
From: Mark Aaron Shirley <maspwr@gmail.com>
Date: Sun, 14 Jul 2013 18:18:39 -0700
Subject: [PATCH 09/13] Fix docs typo

---
 docs/api-guide/serializers.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/api-guide/serializers.md b/docs/api-guide/serializers.md
index 23c999429..022853caa 100644
--- a/docs/api-guide/serializers.md
+++ b/docs/api-guide/serializers.md
@@ -187,7 +187,7 @@ Similarly if a nested representation should be a list of items, you should pass
 
 Validation of nested objects will work the same as before.  Errors with nested objects will be nested under the field name of the nested object.
 
-    serializer = CommentSerializer(comment, data={'user': {'email': 'foobar', 'user': 'doe'}, 'content': 'baz'})
+    serializer = CommentSerializer(comment, data={'user': {'email': 'foobar', 'username': 'doe'}, 'content': 'baz'})
     serializer.is_valid()
     # False
     serializer.errors

From abe655e061871a568cccf473414e350f3eb61d8b Mon Sep 17 00:00:00 2001
From: Yuri Prezument <y@yprez.com>
Date: Mon, 12 Aug 2013 21:01:37 +0300
Subject: [PATCH 10/13] Make OneToOneSource.target nullable

---
 rest_framework/tests/test_relations_nested.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/rest_framework/tests/test_relations_nested.py b/rest_framework/tests/test_relations_nested.py
index 8325580f6..30229687c 100644
--- a/rest_framework/tests/test_relations_nested.py
+++ b/rest_framework/tests/test_relations_nested.py
@@ -10,7 +10,8 @@ class OneToOneTarget(models.Model):
 
 class OneToOneSource(models.Model):
     name = models.CharField(max_length=100)
-    target = models.OneToOneField(OneToOneTarget, related_name='source')
+    target = models.OneToOneField(OneToOneTarget, related_name='source',
+                                  null=True, blank=True)
 
 
 class OneToManyTarget(models.Model):
@@ -21,7 +22,7 @@ class OneToManySource(models.Model):
     name = models.CharField(max_length=100)
     target = models.ForeignKey(OneToManyTarget, related_name='sources')
 
-        
+
 class ReverseNestedOneToOneTests(TestCase):
     def setUp(self):
         class OneToOneSourceSerializer(serializers.ModelSerializer):

From 901d2b0eb8270befa051510e190f3d5679086c7f Mon Sep 17 00:00:00 2001
From: Yuri Prezument <y@yprez.com>
Date: Mon, 12 Aug 2013 21:02:59 +0300
Subject: [PATCH 11/13] Failing test case for nullifying nested object

---
 rest_framework/tests/test_relations_nested.py | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/rest_framework/tests/test_relations_nested.py b/rest_framework/tests/test_relations_nested.py
index 30229687c..d393b0c35 100644
--- a/rest_framework/tests/test_relations_nested.py
+++ b/rest_framework/tests/test_relations_nested.py
@@ -180,6 +180,25 @@ class ForwardNestedOneToOneTests(TestCase):
         ]
         self.assertEqual(serializer.data, expected)
 
+    def test_one_to_one_update_to_null(self):
+        data = {'id': 3, 'name': 'source-3-updated', 'target': None}
+        instance = OneToOneSource.objects.get(pk=3)
+        serializer = self.Serializer(instance, data=data)
+        self.assertTrue(serializer.is_valid())
+        obj = serializer.save()
+
+        self.assertEqual(serializer.data, data)
+        self.assertEqual(obj.name, 'source-3-updated')
+        self.assertEqual(obj.target, None)
+
+        queryset = OneToOneSource.objects.all()
+        serializer = self.Serializer(queryset, many=True)
+        expected = [
+            {'id': 1, 'name': 'source-1', 'target': {'id': 1, 'name': 'target-1'}},
+            {'id': 2, 'name': 'source-2', 'target': {'id': 2, 'name': 'target-2'}},
+            {'id': 3, 'name': 'source-3-updated', 'target': None}
+        ]
+        self.assertEqual(serializer.data, expected)
 
     # TODO: Nullable 1-1 tests
     # def test_one_to_one_delete(self):

From ff1efcf60f0a9b66cdb736f8c0b2cfe2fc84cdf5 Mon Sep 17 00:00:00 2001
From: Yuri Prezument <y@yprez.com>
Date: Mon, 12 Aug 2013 18:08:23 +0300
Subject: [PATCH 12/13] If null or blank - don't save the nested object

---
 rest_framework/serializers.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index d8f9145ec..2b260c256 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -522,7 +522,7 @@ class BaseSerializer(WritableField):
             if self.object._deleted:
                 [self.delete_object(item) for item in self.object._deleted]
         else:
-            self.save_object(self.object, **kwargs)        
+            self.save_object(self.object, **kwargs)
 
         return self.object
 
@@ -891,7 +891,8 @@ class ModelSerializer(Serializer):
             # Nested relationships need to be saved before we can save the
             # parent instance.
             for field_name, sub_object in obj._nested_forward_relations.items():
-                self.save_object(sub_object)
+                if sub_object:
+                    self.save_object(sub_object)
                 setattr(obj, field_name, sub_object)
 
         obj.save(**kwargs)

From e03854ba6a74428675c40d469a7768cc5131035f Mon Sep 17 00:00:00 2001
From: Tom Christie <tom@tomchristie.com>
Date: Fri, 23 Aug 2013 14:06:14 +0100
Subject: [PATCH 13/13] Tweaks to display nested data in empty serializers

---
 rest_framework/relations.py   | 9 +++++++--
 rest_framework/serializers.py | 4 ++--
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/rest_framework/relations.py b/rest_framework/relations.py
index edaf76d6e..7408758e6 100644
--- a/rest_framework/relations.py
+++ b/rest_framework/relations.py
@@ -134,9 +134,9 @@ class RelatedField(WritableField):
             value = obj
 
             for component in source.split('.'):
-                value = get_component(value, component)
                 if value is None:
                     break
+                value = get_component(value, component)
         except ObjectDoesNotExist:
             return None
 
@@ -567,8 +567,13 @@ class HyperlinkedIdentityField(Field):
         May raise a `NoReverseMatch` if the `view_name` and `lookup_field`
         attributes are not configured to correctly match the URL conf.
         """
-        lookup_field = getattr(obj, self.lookup_field)
+        lookup_field = getattr(obj, self.lookup_field, None)
         kwargs = {self.lookup_field: lookup_field}
+
+        # Handle unsaved object case
+        if lookup_field is None:
+            return None
+
         try:
             return reverse(view_name, kwargs=kwargs, request=request, format=format)
         except NoReverseMatch:
diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 2b260c256..22525964c 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -338,9 +338,9 @@ class BaseSerializer(WritableField):
             value = obj
 
             for component in source.split('.'):
-                value = get_component(value, component)
                 if value is None:
-                    break
+                    return self.to_native(None)
+                value = get_component(value, component)
         except ObjectDoesNotExist:
             return None