#10450: Savepoint should not assume an opened connection
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Reporter: jdunck | Owner: nobody
Status: new | Milestone:
Component: Database layer (models, ORM) | Version: 1.0
Keywords: | Stage: Unreviewed
Has_patch: 1 |
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Using django transaction.savepoint() without having previously used a
cursor fails if the backend actually supports savepoints.
e.g. Using postgres:
{{{
Python 2.5.2 (r252:60911, Mar 18 2008, 15:01:36)
[GCC 4.0.1 (Apple Inc. build 5465)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from django.db import transaction
>>> transaction.savepoint()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Users/jeremydunck/work/django/g-django/django/db/transaction.py",
line 188, in savepoint
connection._savepoint(sid)
File
"/Users/jeremydunck/work/django/g-django/django/db/backends/__init__.py",
line 43, in _savepoint
self.connection.cursor().execute(self.ops.savepoint_create_sql(sid))
AttributeError: 'NoneType' object has no attribute 'cursor'
}}}
It seems this problem has existed since savepoints were introduced, but I
found it by trying to use the cached_db sessions backend.
In any case, the problem is that the savepoint family of methods on
BaseDatabaseWrapper make the assumption that self.connection has been
initiailized-- this is not a safe assumption. self.connection is
initialized the first time BaseDatabaseWrapper.cursor is called, and that
may not have happened before BaseDatabaseWrapper._savepoint*.
In all cases, ._savepoint* goes on to use connection.cursor, so I think
it's safe to just use self.cursor() directly rather than
self.connection.cursor().
Patch attached.
Unfortunately, I'm not sure how to make a test for this, because django's
test suite itself uses django.db.connection.
At least it is easy to reproduce. :-)
--
Ticket URL: <http://code.djangoproject.com/ticket/10450>
Django <http://code.djangoproject.com/>
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