Merge pull request #438 from maspwr/partial-update

Add support for partial serializer updates

docs/api-guide/serializers.md

@@ -77,6 +77,10 @@ When deserializing data, we can either create a new instance, or update an exist
     serializer = CommentSerializer(data=data)           # Create new instance
     serializer = CommentSerializer(comment, data=data)  # Update `instance`
 
+By default, serializers must be passed values for all required fields or they will throw validation errors.  You can use the `partial` argument in order to allow partial updates.
+
+    serializer = CommentSerializer(comment, data={'content': u'foo bar'}, partial=True)  # Update `instance` with partial data
+
 ## Validation
 
 When deserializing data, you always need to call `is_valid()` before attempting to access the deserialized object.  If any validation errors occur, the `.errors` and `.non_field_errors` properties will contain the resulting error messages.

rest_framework/fields.py

@@ -54,6 +54,8 @@ class Field(object):
         self.parent = parent
         self.root = parent.root or parent
         self.context = self.root.context
+        if self.root.partial:
+            self.required = False 
 
     def field_from_native(self, data, files, field_name, into):
         """

rest_framework/serializers.py

@@ -91,12 +91,13 @@ class BaseSerializer(Field):
     _options_class = SerializerOptions
     _dict_class = SortedDictWithMetadata  # Set to unsorted dict for backwards compatibility with unsorted implementations.
 
-    def __init__(self, instance=None, data=None, files=None, context=None, **kwargs):
+    def __init__(self, instance=None, data=None, files=None, context=None, partial=False, **kwargs):
         super(BaseSerializer, self).__init__(**kwargs)
         self.opts = self._options_class(self.Meta)
         self.fields = copy.deepcopy(self.base_fields)
         self.parent = None
         self.root = None
+        self.partial = partial
 
         self.context = context or {}
 

rest_framework/tests/serializer.py

@@ -115,6 +115,18 @@ class BasicTests(TestCase):
         self.assertTrue(serializer.object is expected)
         self.assertEquals(serializer.data['sub_comment'], 'And Merry Christmas!')
 
+    def test_partial_update(self):
+        msg = 'Merry New Year!'
+        partial_data = {'content': msg}
+        serializer = CommentSerializer(self.comment, data=partial_data)
+        self.assertEquals(serializer.is_valid(), False)
+        serializer = CommentSerializer(self.comment, data=partial_data, partial=True)
+        expected = self.comment
+        self.assertEqual(serializer.is_valid(), True)
+        self.assertEquals(serializer.object, expected)
+        self.assertTrue(serializer.object is expected)
+        self.assertEquals(serializer.data['content'], msg)
+
     def test_model_fields_as_expected(self):
         """
         Make sure that the fields returned are the same as defined