id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
30408	CheckConstraint with lookup using LIKE & % crash on Oracle and PostgreSQL.	David Sanders	Simon Charette	"Given the following model:

{{{
class Foo(models.Model):
    bar = models.CharField(max_length=255)

    class Meta:
        constraints = (
            models.CheckConstraint(
                check=models.Q(bar__startswith='BAR'),
                name='check_bar_starts_with_BAR',
            ),
        )
}}}

Running migrate with PostgreSQL will result in an exception:

{{{
davids ~/projects/test_startswith_constraint $ ./manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, sample, sessions
Running migrations:
  Applying contenttypes.0001_initial... OK
  Applying auth.0001_initial... OK
  Applying admin.0001_initial... OK
  Applying admin.0002_logentry_remove_auto_add... OK
  Applying admin.0003_logentry_add_action_flag_choices... OK
  Applying contenttypes.0002_remove_content_type_name... OK
  Applying auth.0002_alter_permission_name_max_length... OK
  Applying auth.0003_alter_user_email_max_length... OK
  Applying auth.0004_alter_user_username_opts... OK
  Applying auth.0005_alter_user_last_login_null... OK
  Applying auth.0006_require_contenttypes_0002... OK
  Applying auth.0007_alter_validators_add_error_messages... OK
  Applying auth.0008_alter_user_username_max_length... OK
  Applying auth.0009_alter_user_last_name_max_length... OK
  Applying auth.0010_alter_group_name_max_length... OK
  Applying auth.0011_update_proxy_permissions... OK
  Applying sample.0001_initial...Traceback (most recent call last):
  File ""./manage.py"", line 21, in <module>
    main()
  File ""./manage.py"", line 17, in main
    execute_from_command_line(sys.argv)
  File ""/Users/davids/src/django/django/core/management/__init__.py"", line 381, in execute_from_command_line
    utility.execute()
  File ""/Users/davids/src/django/django/core/management/__init__.py"", line 375, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File ""/Users/davids/src/django/django/core/management/base.py"", line 323, in run_from_argv
    self.execute(*args, **cmd_options)
  File ""/Users/davids/src/django/django/core/management/base.py"", line 364, in execute
    output = self.handle(*args, **options)
  File ""/Users/davids/src/django/django/core/management/base.py"", line 83, in wrapped
    res = handle_func(*args, **kwargs)
  File ""/Users/davids/src/django/django/core/management/commands/migrate.py"", line 233, in handle
    fake_initial=fake_initial,
  File ""/Users/davids/src/django/django/db/migrations/executor.py"", line 117, in migrate
    state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
  File ""/Users/davids/src/django/django/db/migrations/executor.py"", line 147, in _migrate_all_forwards
    state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
  File ""/Users/davids/src/django/django/db/migrations/executor.py"", line 245, in apply_migration
    state = migration.apply(state, schema_editor)
  File ""/Users/davids/src/django/django/db/migrations/migration.py"", line 124, in apply
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
  File ""/Users/davids/src/django/django/db/migrations/operations/models.py"", line 827, in database_forwards
    schema_editor.add_constraint(model, self.constraint)
  File ""/Users/davids/src/django/django/db/backends/base/schema.py"", line 346, in add_constraint
    self.execute(sql)
  File ""/Users/davids/src/django/django/db/backends/base/schema.py"", line 138, in execute
    cursor.execute(sql, params)
  File ""/Users/davids/src/django/django/db/backends/utils.py"", line 99, in execute
    return super().execute(sql, params)
  File ""/Users/davids/src/django/django/db/backends/utils.py"", line 67, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File ""/Users/davids/src/django/django/db/backends/utils.py"", line 76, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File ""/Users/davids/src/django/django/db/backends/utils.py"", line 84, in _execute
    return self.cursor.execute(sql, params)
IndexError: tuple index out of range
}}}

This is due to the SQL being passed to `execute()` has an unescaped `%`:

{{{
> /Users/davids/src/django/django/db/backends/utils.py(85)_execute()
     84                 import ipdb; ipdb.set_trace()
---> 85                 return self.cursor.execute(sql, params)
     86

ipdb> sql
'ALTER TABLE ""sample_foo"" ADD CONSTRAINT ""check_bar_starts_with_BAR"" CHECK (""bar""::text LIKE \'BAR%\')'
}}}

Note that this runs fine with SQLite but is problematic for PostgreSQL."	Bug	closed	Database layer (models, ORM)	2.2	Release blocker	fixed		Ian Foote	Ready for checkin	1	0	0	0	0	0