Fixed #17653 -- Allowed using zero as AutoFields value on MySQL if NO_AUTO_VALUE_ON_ZERO SQL mode is enabled.

1 files changed, 6 insertions, 2 deletions

diff --git a/django/db/backends/mysql/operations.py b/django/db/backends/mysql/operations.py
index ffddb64e3c..05523fcdbe 100644
--- a/django/db/backends/mysql/operations.py
+++ b/django/db/backends/mysql/operations.py
@@ -227,8 +227,9 @@ class DatabaseOperations(BaseDatabaseOperations):
         ]
 
     def validate_autopk_value(self, value):
-        # MySQLism: zero in AUTO_INCREMENT field does not work. Refs #17653.
-        if value == 0:
+        # Zero in AUTO_INCREMENT field does not work without the
+        # NO_AUTO_VALUE_ON_ZERO SQL mode.
+        if value == 0 and not self.connection.features.allows_auto_pk_0:
             raise ValueError('The database backend does not accept 0 as a '
                              'value for AutoField.')
         return value
@@ -266,6 +267,9 @@ class DatabaseOperations(BaseDatabaseOperations):
     def max_name_length(self):
         return 64
 
+    def pk_default_value(self):
+        return 'NULL'
+
     def bulk_insert_sql(self, fields, placeholder_rows):
         placeholder_rows_sql = (", ".join(row) for row in placeholder_rows)
         values_sql = ", ".join("(%s)" % sql for sql in placeholder_rows_sql)