Transaction management does not catch all exceptions

[jim <jim-django@…>]

Expectation:
When a view is decorated with commit_on_success, any exception raised in that view should cause a rollback of the current transaction. If no exception occurs, the transaction should be committed.

Experience:
There are many exceptions that are not caught by commit_on_success. When one of these is raised, neither a rollback nor a commit is done. This causes a TransactionManagementError in leave_transaction_management().

The only exceptions caught are subclasses of Python's built in Exception class. Since Python allows any object to be raised as an exception, this leaves an unprotected path in the code.

For example (untested, just an illustration):

@commit_on_success
def my_view(request):
   raise "simple debug exception"

The object being raised will not match commit_on_success's handler, and the error condition is triggered.

Note: Yes, string exceptions are deprecated. But they are still possible, and must be guarded against.

Simple patch attached.

[jim <jim-django@…>]

simple patch

[Bernd Schlapsi]

I think #6623 is related to this issue

[jim <jim-django@…>]

Notice that this is not the classic misguided "naked except", as it re-raises immediately after the rollback.

[Malcolm Tredinnick]

(In [8419]) Fixed #7241 -- More robust exception catching in the transaction management
code. As pointed out in the ticket, Python still lets you raise all sorts of
odd things as exceptions (e.g. strings), so even though they're bad form, we
should still handle them. We do that cleanly now. Thanks to jim-django@…
for the patch.

[Jacob]

Milestone 1.0 deleted