From b0c5f9db2f28324d77a841f504a24a5b51935552 Mon Sep 17 00:00:00 2001
From: Juan Gutierrez <juanny.gee@gmail.com>
Date: Fri, 3 Jul 2015 12:28:48 -0400
Subject: [PATCH] allow a non-required nested serializer to validate correctly
 when receiving multipart data

---
 rest_framework/serializers.py   |  2 +-
 tests/test_serializer_nested.py | 43 +++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 7afddfd82..80b7c6d6d 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -367,7 +367,7 @@ class Serializer(BaseSerializer):
         # We override the default field access in order to support
         # nested HTML forms.
         if html.is_html_input(dictionary):
-            return html.parse_html_dict(dictionary, prefix=self.field_name)
+            return html.parse_html_dict(dictionary, prefix=self.field_name) or empty
         return dictionary.get(self.field_name, empty)
 
     def run_validation(self, data=empty):
diff --git a/tests/test_serializer_nested.py b/tests/test_serializer_nested.py
index f5e4b26ad..24415db60 100644
--- a/tests/test_serializer_nested.py
+++ b/tests/test_serializer_nested.py
@@ -38,3 +38,46 @@ class TestNestedSerializer:
         }
         serializer = self.Serializer()
         assert serializer.data == expected_data
+
+
+class TestNotRequiredNestedSerializer:
+    def setup(self):
+        class NestedSerializer(serializers.Serializer):
+            one = serializers.IntegerField(max_value=10)
+
+        class TestSerializer(serializers.Serializer):
+            nested = NestedSerializer(required=False)
+
+        self.Serializer = TestSerializer
+
+        class FakeMultiDict(dict):
+            """
+            Use this to fake a `format="multipart"` request, because
+            `utils.is_html_input()` returns `True` when the dict object has
+            an attribute of "getlist".
+            """
+            def getlist(self, value, default=None):
+                if value in self:
+                    return [self[value]]
+                else:
+                    return [] if default is None else default
+
+        self.FakeMultiDict = FakeMultiDict
+
+    def test_json_validate(self):
+        input_data = {}
+        serializer = self.Serializer(data=input_data)
+        assert serializer.is_valid()
+
+        input_data = {'nested': {'one': '1'}}
+        serializer = self.Serializer(data=input_data)
+        assert serializer.is_valid()
+
+    def test_multipart_validate(self):
+        input_data = self.FakeMultiDict()
+        serializer = self.Serializer(data=input_data)
+        assert serializer.is_valid()
+
+        input_data = self.FakeMultiDict(**{'nested.one': '1'})
+        serializer = self.Serializer(data=input_data)
+        assert serializer.is_valid()