Ticket #17653: ticket_17653_v2.diff

django/db/backends/__init__.py

@@ -762 +762 @@
     # need not necessarily be implemented using "LIKE" in the backend.
     prep_for_iexact_query = prep_for_like_query
 
+    def validate_autopk_value(self, value):
+        """
+        Certain backends does not accept certain values for primary key
+        (for example zero in MySQL). It raises ValueError if value is invalid
+        otherwise it returns validated value.
+        """
+        return value
+
     def value_to_db_date(self, value):
         """
         Transform a date value to an object compatible with what is expected

django/db/backends/mysql/base.py

@@ -257 +257 @@
         else:
             return []
 
+    def validate_autopk_value(self, value):
+        if value == 0:
+            raise ValueError('The database backend does not accept %s as a '
+                             'value for primary key field.' % (value,))
+        return value
+
     def value_to_db_datetime(self, value):
         if value is None:
             return None

django/db/models/fields/__init__.py

@@ -531 +531 @@
     def validate(self, value, model_instance):
         pass
 
+    def get_db_prep_value(self, value, connection, prepared=False):
+        if not prepared:
+            value = self.get_prep_value(value)
+            value = connection.ops.validate_autopk_value(value)
+        return value
+
     def get_prep_value(self, value):
         if value is None:
             return None

tests/regressiontests/backends/tests.py

@@ -13 +13 @@
 from django.db.backends.signals import connection_created
 from django.db.backends.postgresql_psycopg2 import version as pg_version
 from django.db.utils import ConnectionHandler, DatabaseError, load_backend
-from django.test import TestCase, skipUnlessDBFeature, TransactionTestCase
+from django.test import (TestCase, skipUnlessDBFeature, skipIfDBFeature,
+    TransactionTestCase)
 from django.test.utils import override_settings
 from django.utils import unittest
-
 from . import models
 
 
@@ -618 +618 @@
         self.assertRaisesRegexp(ImproperlyConfigured,
             "Try using django.db.backends.sqlite3 instead",
             load_backend, 'sqlite3')
+
+
+class MySQLPKZeroTests(TestCase):
+    """
+    Zero as id for autofield should raise exception in MySQL, because MySQL
+    handles zero in a specific way.
+    """
+
+    @skipIfDBFeature('allows_primary_key_0')
+    def test_zero_as_autoval(self):
+        with self.assertRaises(ValueError):
+            models.Square.objects.create(id=0, root=0, square=1)
+ No newline at end of file