#13974: saving object with multi-table inheritance is not transactional by
default
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Reporter: ccurvey | Owner: nobody
Status: new | Milestone:
Component: Database layer (models, ORM) | Version: 1.2
Keywords: | Stage: Unreviewed
Has_patch: 0 |
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if you are using multi-table inheritance, and there is some problem
writing to one of the tables, some tables are updated, and some are not.
(MySQL 5.x on Ubuntu, Django 1.2rc 1 on Windows)
1) Set up a new project with database settings like so:
{{{
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.mysql',
'NAME': 'mydb',
'USER': 'myuser',
'PASSWORD': 'mypassword'
'HOST': 'myhost',
'PORT': '',
'OPTIONS' : {
'init_command' : 'set storage_engine=INNODB',
},
}
}
}}}
2) Now set up some models that use inheritance:
{{{
from django.db import models
# Create your models here.
class Foo(models.Model):
a = models.IntegerField()
class Bar(Foo):
b = models.IntegerField()
}}}
3) Now create a script that does something obviously wrong.
{{{
import sys
sys.path.append(r"C:\users\ccurvey")
sys.path.append(r"C:\users\ccurvey\testme")
sys.path.append(r"C:\users\ccurvey\testme\foobar")
import os
os.environ["DJANGO_SETTINGS_MODULE"] = 'settings'
from foobar.models import Bar
# try testing something that is clearly wrong.
bar = Bar(a=1, b="A")
# this is going to throw a ValueError
bar.save()
}}}
4) Now go look at the underlying tables in MySQL:
{{{
mysql> select * from foobar_foo;
+----+---+
| id | a |
+----+---+
| 1 | 1 |
+----+---+
1 row in set (0.00 sec)
mysql> select * from foobar_bar;
Empty set (0.00 sec)
}}}
The workaround is to add @commit_on_success and a save() method to Bar,
like so, but it seems (to me) like this should be unncessary.
{{{
from django.db.transaction import commit_on_success
class Bar(Foo):
b = models.IntegerField()
@commit_on_success
def save(self):
super(Bar, self).save()
}}}
--
Ticket URL: <http://code.djangoproject.com/ticket/13974>
Django <http://code.djangoproject.com/>
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