Fix for case of ListSerializer with single item (encode#4609)

Author: lovelydinosaur

rest_framework/serializers.py

@@ -507,7 +507,7 @@ def data(self):
     @property
     def errors(self):
         ret = super(Serializer, self).errors
-        if isinstance(ret, list) and len(ret) == 1 and ret[0].code == 'null':
+        if isinstance(ret, list) and len(ret) == 1 and getattr(ret[0], 'code', None) == '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')
@@ -705,7 +705,7 @@ def data(self):
     @property
     def errors(self):
         ret = super(ListSerializer, self).errors
-        if isinstance(ret, list) and len(ret) == 1 and ret[0].code == 'null':
+        if isinstance(ret, list) and len(ret) == 1 and getattr(ret[0], 'code', None) == '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')

tests/test_serializer.py

@@ -357,3 +357,16 @@ def test_validation_success(self):
         assert serializer.is_valid()
         assert serializer.validated_data == {'name': '2'}
         assert serializer.errors == {}
+
+
+class Test4606Regression:
+    def setup(self):
+        class ExampleSerializer(serializers.Serializer):
+            name = serializers.CharField(required=True)
+            choices = serializers.CharField(required=True)
+        self.Serializer = ExampleSerializer
+
+    def test_4606_regression(self):
+        serializer = self.Serializer(data=[{"name": "liz"}], many=True)
+        with pytest.raises(serializers.ValidationError):
+            serializer.is_valid(raise_exception=True)