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
15776	Delete Regression in Django 1.3	aaron.l.madison@…	Luke Plant	"I have found a bug the way Django 1.3 carries out its cascade delete using MySQL. (the operation works fine in django 1.2.5)

Here is a stripped example from our production data.

{{{
from django.db import models

class Policy(models.Model):
    policy_number = models.CharField(max_length=10)

class Version(models.Model):
    policy = models.ForeignKey(Policy)

class Location(models.Model):
    version = models.ForeignKey(Version, blank=True, null=True)

class Item(models.Model):
    version = models.ForeignKey(Version)
    location = models.ForeignKey(Location, blank=True, null=True)

class ItemRateCode(models.Model):
    item = models.ForeignKey(Item)

class PropertyItem(models.Model):
    item_rate_code = models.ForeignKey(ItemRateCode)

class Coverage(models.Model):
    version = models.ForeignKey(Version)
    item_rate_code = models.ForeignKey(ItemRateCode)
}}}

After you syncdb, execute the following to load the data and try to delete the policy:

{{{
from myapp.models import Policy, Version, Location, Item
from myapp.models import ItemRateCode, PropertyItem, Coverage

policy = Policy.objects.create(pk=1, policy_number=""1234"")
version = Version.objects.create(policy=policy)
location = Location.objects.create(version=version)

item1 = Item.objects.create(version=version, location=location)
item2 = Item.objects.create(version=version, location=location)

# one for each item
item_rate_code1 = ItemRateCode.objects.create(item=item1)
item_rate_code2 = ItemRateCode.objects.create(item=item2)

# one for each item_rate_code
coverage1 = Coverage.objects.create(version=version, item_rate_code=item_rate_code1)
coverage2 = Coverage.objects.create(version=version, item_rate_code=item_rate_code2)

# one for each item_rate_code
property_item1 = PropertyItem.objects.create(item_rate_code=item_rate_code1)
property_item2 = PropertyItem.objects.create(item_rate_code=item_rate_code2)

policy = Policy.objects.get(pk=1)
policy.delete()
}}}

(I have included a sample project with a failing/blowing up testcase... the test passes on 1.2.5)

For some reason, the delete collector I believe is trying to delete the ""Version"" before it has deleted the ""Item""s


"	Bug	closed	Database layer (models, ORM)	1.3	Release blocker	fixed	db mysql delete	aaron.l.madison@…	Accepted	0	0	1	0	0	0