Fixed django#17653 -- Changed MySQL backend to raise a ValueError if zero is used as an AutoField value.

Thanks to Sylvain Lebon for the report, krzysiumed for the patch and charettes and claudep for reviews. git-svn-id: http://code.djangoproject.com/svn/django/trunk@17933 bcc190cf-cafb-0310-a4f2-bffc1f526a37

Author: akaariai

django/db/backends/__init__.py

@@ -770,6 +770,14 @@ def prep_for_like_query(self, x):
  # 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 do not accept some values for "serial" fields
+ (for example zero in MySQL). This method will raise a ValueError
+ if the value is invalid, otherwise 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

@@ -276,6 +276,13 @@ def sql_flush(self, style, tables, sequences):
  else:
  return []
 
+ def validate_autopk_value(self, value):
+ # MySQLism: zero in AUTO_INCREMENT field does not work. Refs #17653.
+ if value == 0:
+ raise ValueError('The database backend does not accept 0 as a '
+ 'value for AutoField.')
+ return value
+
  def value_to_db_datetime(self, value):
  if value is None:
  return None

django/db/models/fields/__init__.py

@@ -531,6 +531,12 @@ def to_python(self, value):
  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

@@ -13,7 +13,8 @@
 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
 
@@ -642,3 +643,15 @@ def test_old_style_backends_raise_useful_exception(self):
  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
+ does not allow zero for automatic primary key.
+ """
+
+ @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)

tests/regressiontests/bulk_create/tests.py

@@ -2,7 +2,7 @@
 
 from operator import attrgetter
 
-from django.test import TestCase, skipUnlessDBFeature
+from django.test import TestCase, skipIfDBFeature, skipUnlessDBFeature
 
 from .models import Country, Restaurant, Pizzeria, State
 
@@ -56,4 +56,16 @@ def test_non_auto_increment_pk(self):
  ])
  self.assertQuerysetEqual(State.objects.order_by("two_letter_code"), [
  "CA", "IL", "ME", "NY",
- ], attrgetter("two_letter_code"))
+ ], attrgetter("two_letter_code"))
+
+ @skipIfDBFeature('allows_primary_key_0')
+ def test_zero_as_autoval(self):
+ """
+ Zero as id for AutoField should raise exception in MySQL, because MySQL
+ does not allow zero for automatic primary key.
+ """
+
+ valid_country = Country(name='Germany', iso_two_letter='DE')
+ invalid_country = Country(id=0, name='Poland', iso_two_letter='PL')
+ with self.assertRaises(ValueError):
+ Country.objects.bulk_create([valid_country, invalid_country])