Transaction middleware only creates transaction for default database

[david.winterbottom@…]

The current implementation of django.middleware.TransactionMiddleware does not create a transaction for each database defined in the DATABASES setting, only the one defined by DEFAULT_DB_ALIAS. You can see this quite clearly by reading the source of: -
https://code.djangoproject.com/browser/django/trunk/django/db/utils.py.

Shouldn't the middleware manage a transaction for each database defined in the DATABASES setting?

Happy to provide tests and patch if this makes sense - I just wanted to check this wasn't a design decision first. I did email the mailing list with this question but no responses received:

​https://groups.google.com/group/django-developers/browse_thread/thread/bba4ee95676086e3/e76c7885db4c77f8?hl=en&lnk=gst&q=middleware+transaction#e76c7885db4c77f8

[anonymous]

Source link should be https://code.djangoproject.com/browser/django/trunk/django/middleware/transaction.py

[Aymeric Augustin]

Since we can't enforce transactional behavior across databases, it's more reasonable for the transaction middleware to manage only the default database. Otherwise, we'd risk creating unreasonable expectations.

Therefore, and in order to avoid a backwards incompatible change, I propose to document the current behavior (in topics/db/transactions.txt).

[David Winterbottom]

That seems like the right solution to me. Would you like me to make the appropriate edits to the docs and send a patch? Or is there a different process for documentation writing?

[Aymeric Augustin]

Replying to codeinthehole:

Would you like me to make the appropriate edits to the docs and send a patch?

Yes, that's the next step.

You can assign the ticket to yourself when you start working on it.

[David Winterbottom]

First draft of doc update

[Karen Tracey]

It's not fixed until a code or doc change has been checked into the repo.

[anonymous]

Should the docs also clarify whether this transaction applies to the test database?

[Tim Graham <timograham@…>]

In [5d81ad1af14ee3127b53f923687ed5c4e00329ee]:

Fixed #17168 - Noted TransactionMiddleware only works with "default" database alias.

Thanks codeinthehole for the draft patch.

[Tim Graham <timograham@…>]

In [a89e76d15149c0758e6459d695ce60722cad7101]:

[1.4.X] Fixed #17168 - Noted TransactionMiddleware only works with "default" database alias.

Thanks codeinthehole for the draft patch.

Backport of 5d81ad1af1 from master