While exploring the Django transaction stuff (in 1.4rc1), I ran across the
following behavior. I use commit_on_success as the example here, but the other
transaction decorators/context managers have the same issue.
It seems to me to be a bug, but I wanted to confirm this before I opened an
issue.
The configuration is running Django using the psycopg2 backend, with 'OPTIONS':
{ 'autocommit': True, }
Consider the following code:
from django.db import transaction, DEFAULT_DB_ALIAS, connections
from myapp.mymodels import X
x = X.objects.get(id=1)
print connections[DEFAULT_DB_ALIAS].isolation_level # As expected, it's 0
here.
x.myfield = 'Foo'
with commit_on_success():
x.save()
print connections[DEFAULT_DB_ALIAS].isolation_level # As expected, it's
1 here.
print connections[DEFAULT_DB_ALIAS].isolation_level # It's now 1 here, but
shouldn't it be back to 0?
The bug seems to be that the isolation level does not get reset back to 0, even
when leaving connection management. This means that any further operations on
the database will open a new transaction (since psycopg2 will automatically
open), but this transaction won't be managed in any way.
The bug appears to be in
django.db.backends.BaseDatabaseWrapper.leave_transaction_management; it calls
the _leave_transaction_management hook first thing, but this means that
is_managed() will return true (since the decorators call managed(True)), which
means that _leave_transaction_management in the psycopg2 backend will not reset
the transaction isolation level; the code in the psycopg2 backend seems to
assume that it will be run in the new transaction context, not the previous one.
Or am I missing something?
--
-- Christophe Pettus
x...@thebuild.com
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