Merge pull request #3801 from koordinates/fix-nested-validation-error

Fix nested validation error being rendered incorrectly.

rest_framework/serializers.py

@@ -306,7 +306,7 @@ def get_validation_error_detail(exc):
         # If errors may be a dict we use the standard {key: list of values}.
         # Here we ensure that all the values are *lists* of errors.
         return {
-            key: value if isinstance(value, list) else [value]
+            key: value if isinstance(value, (list, dict)) else [value]
             for key, value in exc.detail.items()
         }
     elif isinstance(exc.detail, list):

tests/test_validation.py

@@ -49,6 +49,24 @@ class Meta:
         fields = ('renamed',)
 
 
+class TestNestedValidationError(TestCase):
+    def test_nested_validation_error_detail(self):
+        """
+        Ensure nested validation error detail is rendered correctly.
+        """
+        e = serializers.ValidationError({
+            'nested': {
+                'field': ['error'],
+            }
+        })
+
+        self.assertEqual(serializers.get_validation_error_detail(e), {
+            'nested': {
+                'field': ['error'],
+            }
+        })
+
+
 class TestPreSaveValidationExclusionsSerializer(TestCase):
     def test_renamed_fields_are_model_validated(self):
         """