From b4199704316bd2d67281cbc3cf946eab9bded407 Mon Sep 17 00:00:00 2001
From: Tom Christie <tom@tomchristie.com>
Date: Wed, 12 Oct 2016 10:47:17 +0100
Subject: [PATCH] Handle empty data with serializer (#4564)

---
 rest_framework/serializers.py   | 10 ++++++++++
 tests/test_serializer.py        |  6 ++++++
 tests/test_serializer_nested.py |  6 ++++++
 3 files changed, 22 insertions(+)

diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index a6ed7d87e..02c21da15 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -507,6 +507,11 @@ class Serializer(BaseSerializer):
     @property
     def errors(self):
         ret = super(Serializer, self).errors
+        if isinstance(ret, list) and len(ret) == 1 and ret[0].code == 'null':
+            # Edge case. Provide a more descriptive error than
+            # "this field may not be null", when no data is passed.
+            detail = ErrorDetail('No data provided', code='null')
+            ret = {api_settings.NON_FIELD_ERRORS_KEY: [detail]}
         return ReturnDict(ret, serializer=self)
 
 
@@ -700,6 +705,11 @@ class ListSerializer(BaseSerializer):
     @property
     def errors(self):
         ret = super(ListSerializer, self).errors
+        if isinstance(ret, list) and len(ret) == 1 and ret[0].code == 'null':
+            # Edge case. Provide a more descriptive error than
+            # "this field may not be null", when no data is passed.
+            detail = ErrorDetail('No data provided', code='null')
+            ret = {api_settings.NON_FIELD_ERRORS_KEY: [detail]}
         if isinstance(ret, dict):
             return ReturnDict(ret, serializer=self)
         return ReturnList(ret, serializer=self)
diff --git a/tests/test_serializer.py b/tests/test_serializer.py
index bd9ef9500..a2817f6a4 100644
--- a/tests/test_serializer.py
+++ b/tests/test_serializer.py
@@ -62,6 +62,12 @@ class TestSerializer:
         with pytest.raises(AssertionError):
             serializer.save()
 
+    def test_validate_none_data(self):
+        data = None
+        serializer = self.Serializer(data=data)
+        assert not serializer.is_valid()
+        assert serializer.errors == {'non_field_errors': ['No data provided']}
+
 
 class TestValidateMethod:
     def test_non_field_error_validate_method(self):
diff --git a/tests/test_serializer_nested.py b/tests/test_serializer_nested.py
index 133600399..efb671918 100644
--- a/tests/test_serializer_nested.py
+++ b/tests/test_serializer_nested.py
@@ -41,6 +41,12 @@ class TestNestedSerializer:
         serializer = self.Serializer()
         assert serializer.data == expected_data
 
+    def test_nested_serialize_no_data(self):
+        data = None
+        serializer = self.Serializer(data=data)
+        assert not serializer.is_valid()
+        assert serializer.errors == {'non_field_errors': ['No data provided']}
+
 
 class TestNotRequiredNestedSerializer:
     def setup(self):