Re: Database inserts with autocommit set to off.

Thanks a lot! I've ended up using `django-transaction-hooks`.

On Monday, July 27, 2015 at 5:49:40 PM UTC+2, Carl Meyer wrote:

Hi Maciej,

On 07/27/2015 07:03 AM, Maciej Gol wrote:
> I've been recently working (porting to Django 1.8) on a project where we
> need to use a few transactions in a single request, and these
> transactions cannot be correctly handled by the `atomic` decorator due
> to functions calls nesting. Basically, we are sending celery tasks at
> the end of some processing, and it requires the results to be visible in
> the database. I'm doing this for each element of a list, thus the celery
> task sending is done right after saving the data to the database. The
> commit should happen between the save and posting the task, and since
> the processing logic is complex, I can't use a decorator here.

I think a better solution to this situation is to use
transaction.atomic, and then use django-transaction-hooks [1] to delay
creation of the Celery task(s) until the transaction is successfully
committed. (Django 1.9 will have transaction-hooks integrated into core.)

 [1] http://django-transaction-hooks.readthedocs.org/en/latest/

> The issue is, when autocommit is set to off, whenever I try to
> `.update()` a `QuerySet` or `.save()` a `Model`, it results in
> `TransactionManagementError: The outermost 'atomic' block cannot use
> savepoint = False when autocommit is off.` error, which is kind of sad
> because I could handle the eventual rollback myself gracefully. Instead,
> django throws me this error in the face.

Yes, this is a known issue in 1.8:
https://code.djangoproject.com/ticket/24921

The ticket describes the needed solution in some detail, it just remains
for someone to code up the patch with a test. Since the issue is a
regression in 1.8, I think such a patch would be backported to the 1.8
branch and appear in the next 1.8.x release.

Carl

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