Re: Ensure an object is saved even when the atomic bock rollsback

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Hi Marc,

On 05/08/2015 07:15 AM, Marc Aymerich wrote:
> I'm using atomic requests, but one of my views needs to save a model
> regardless of wheter the current transaction rolls back or not.
>
> I'm confused about how to proceed with the current autocommit behaviour.
> Do I need to use a different db connection? or perhaps there is some way
> of telling django to ignore autocommit for some particular block ?

You'd need to use a different db connection, since what you're trying to
do violates the very nature of a database transaction. If you were just
trying to run some raw SQL, you could establish the separate connection
yourself manually, but if you're trying to save a Django model, you'll
probably need a second connection defined in your DATABASES setting.

Possible alternatives:

- If you're using a task queuing system (like Celery or rq), queue a
task to perform the save; you can do this without making it conditional
on the transaction committing, as long as your task queue is using a
store other than your primary database (e.g. Redis or RabbitMQ). Usually
when people do this it's unintentional and a bug (they really wanted the
task to execute only if the current transaction committed), but in your
case it could be a feature.

- Switch from ATOMIC_REQUESTS to explicit use of transaction.atomic() in
your views, so that you can place this "no matter what" save in its own
transaction.

Carl

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