From 82c5a9de750f3657a2bde5fa7eaffd7fa0279a5a Mon Sep 17 00:00:00 2001
From: Tom Christie <tom@tomchristie.com>
Date: Mon, 18 Mar 2013 22:24:46 +0000
Subject: [PATCH] Added bulk update functionality and test

---
 rest_framework/serializers.py                 | 34 ++++++++
 .../tests/serializer_bulk_update.py           | 78 +++++++++++++++++++
 2 files changed, 112 insertions(+)

diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index a81cbc291..a39bdee76 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -147,6 +147,7 @@ class BaseSerializer(WritableField):
         self._data = None
         self._files = None
         self._errors = None
+        self._deleted = None
 
     #####
     # Methods to determine which fields to use when (de)serializing objects.
@@ -387,6 +388,13 @@ class BaseSerializer(WritableField):
                 # Propagate errors up to our parent
                 raise NestedValidationError(serializer.errors)
 
+    def get_identity(self, data):
+        """
+        This hook is required for bulk update.
+        It is used to determine the canonical identity of a given object.
+        """
+        return data['id']
+
     @property
     def errors(self):
         """
@@ -408,9 +416,28 @@ class BaseSerializer(WritableField):
             if many:
                 ret = []
                 errors = []
+                update = self.object is not None
+
+                if update:
+                    # If this is a bulk update we need to map all the objects
+                    # to a canonical identity so we can determine which
+                    # individual object is being updated for each item in the
+                    # incoming data
+                    objects = self.object
+                    identities = [self.get_identity(self.to_native(obj)) for obj in objects]
+                    identity_to_objects = dict(zip(identities, objects))
+
                 for item in data:
+                    if update:
+                        # Determine which object we're updating
+                        identity = self.get_identity(item)
+                        self.object = identity_to_objects.pop(identity, None)
+
                     ret.append(self.from_native(item, None))
                     errors.append(self._errors)
+
+                if update:
+                    self._deleted = identity_to_objects.values()
                 self._errors = any(errors) and errors or []
             else:
                 ret = self.from_native(data, files)
@@ -450,6 +477,9 @@ class BaseSerializer(WritableField):
     def save_object(self, obj, **kwargs):
         obj.save(**kwargs)
 
+    def delete_object(self, obj):
+        obj.delete()
+
     def save(self, **kwargs):
         """
         Save the deserialized object and return it.
@@ -458,6 +488,10 @@ class BaseSerializer(WritableField):
             [self.save_object(item, **kwargs) for item in self.object]
         else:
             self.save_object(self.object, **kwargs)
+
+        if self._deleted:
+            [self.delete_object(item) for item in self._deleted]
+
         return self.object
 
 
diff --git a/rest_framework/tests/serializer_bulk_update.py b/rest_framework/tests/serializer_bulk_update.py
index 3ecb23edd..6ed8741c8 100644
--- a/rest_framework/tests/serializer_bulk_update.py
+++ b/rest_framework/tests/serializer_bulk_update.py
@@ -71,3 +71,81 @@ class BulkCreateSerializerTests(TestCase):
         self.assertEqual(serializer.is_valid(), False)
         self.assertEqual(serializer.errors, expected_errors)
 
+
+class BulkUpdateSerializerTests(TestCase):
+
+    def setUp(self):
+        class Book(object):
+            object_map = {}
+
+            def __init__(self, id, title, author):
+                self.id = id
+                self.title = title
+                self.author = author
+
+            def save(self):
+                Book.object_map[self.id] = self
+
+            def delete(self):
+                del Book.object_map[self.id]
+
+        class BookSerializer(serializers.Serializer):
+            id = serializers.IntegerField()
+            title = serializers.CharField(max_length=100)
+            author = serializers.CharField(max_length=100)
+
+            def restore_object(self, attrs, instance=None):
+                if instance:
+                    instance.id = attrs['id']
+                    instance.title = attrs['title']
+                    instance.author = attrs['author']
+                    return instance
+                return Book(**attrs)
+
+        self.Book = Book
+        self.BookSerializer = BookSerializer
+
+        data = [
+            {
+                'id': 0,
+                'title': 'The electric kool-aid acid test',
+                'author': 'Tom Wolfe'
+            }, {
+                'id': 1,
+                'title': 'If this is a man',
+                'author': 'Primo Levi'
+            }, {
+                'id': 2,
+                'title': 'The wind-up bird chronicle',
+                'author': 'Haruki Murakami'
+            }
+        ]
+
+        for item in data:
+            book = Book(item['id'], item['title'], item['author'])
+            book.save()
+
+    def books(self):
+        return self.Book.object_map.values()
+
+    def test_bulk_update_success(self):
+        """
+        Correct bulk update serialization should return the input data.
+        """
+        data = [
+            {
+                'id': 0,
+                'title': 'The electric kool-aid acid test',
+                'author': 'Tom Wolfe'
+            }, {
+                'id': 2,
+                'title': 'Kafka on the shore',
+                'author': 'Haruki Murakami'
+            }
+        ]
+        serializer = self.BookSerializer(self.books(), data=data, many=True)
+        self.assertEqual(serializer.is_valid(), True)
+        self.assertEqual(serializer.data, data)
+        serializer.save()
+        new_data = self.BookSerializer(self.books(), many=True).data
+        self.assertEqual(data, new_data)