Fixed #26743 -- Fixed UnboundLocalError crash when deserializing m2m fields and value isn't iterable.

1 files changed, 14 insertions, 0 deletions

diff --git a/tests/serializers/test_json.py b/tests/serializers/test_json.py
index a804aa1f3a..93e51e124c 100644
--- a/tests/serializers/test_json.py
+++ b/tests/serializers/test_json.py
@@ -252,6 +252,20 @@ class JsonSerializerTestCase(SerializersTestBase, TestCase):
             for obj in serializers.deserialize('json', test_string, ignore=False):
                 obj.save()
 
+    def test_helpful_error_message_for_many2many_not_iterable(self):
+        """
+        Not iterable many-to-many field value throws a helpful error message.
+        """
+        test_string = """[{
+            "pk": 1,
+            "model": "serializers.m2mdata",
+            "fields": {"data": null}
+        }]"""
+
+        expected = "(serializers.m2mdata:pk=1) field_value was 'None'"
+        with self.assertRaisesMessage(DeserializationError, expected):
+            next(serializers.deserialize('json', test_string, ignore=False))
+
 
 class JsonSerializerTransactionTestCase(SerializersTransactionTestBase, TransactionTestCase):
     serializer_name = "json"