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
17112	`ManyRelatedManager.add()` doesn't commit to database	Tai Lee	nobody	"Execute the following in order in two different interactive shells (two processes) to trigger the bug. The problem is that the call to `.add()` is not committed to the database until a second call to `.create()`. If the first process happens to be a management command (for example) and there are no subsequent database writes, the relations are never committed. You can also confirm this by inspecting the database after executing each command.

{{{
# shell 1
>>> from django.contrib.auth.models import *
>>> u = User.objects.create(username='test')
>>> u.groups.add(Group.objects.latest('pk'))
>>> User.objects.get(username='test').groups.all()
[<Group: motivate | members>]

# shell 2
>>> from django.contrib.auth.models import *
>>> User.objects.get(username='test').groups.all()
[]

# shell 1
>>> u2 = User.objects.create(username='test2')

# shell 2
>>> User.objects.get(username='test').groups.all()
[<Group: motivate | members>]

# sql command to check if group has been linked to user
select * from auth_user_groups where user_id = (select id from auth_user where username = 'test');
}}}

I've tested this against trunk, and it was confirmed by ptone who also confirmed that it is a regression from 1.3. I tested on PostgreSQL and SQLite.

I'm not sure how to create an automated test for this, because the problem only exhibits when reading from the database from a different process or transaction.
"	Bug	closed	Database layer (models, ORM)	dev	Release blocker	duplicate	add reverse m2m relation not committed		Accepted	0	0	0	0	0	0