My project is based on standard SQLAlchemy scaffold, ZTE, using ORM.
Pyramid 1.5.8.
I'm trying to catch an IntegrityError (unique key constraint), I've made a
very minimal example
@view_config(route_name='exception_test', renderer='json')
def exception_test(request):
user = DBSession.query(User).filter(User.id == 1).first()
user.tutorial_done = True
DBSession.query(Map).first()
map_obj = Map(user=request.user)
map_obj.name = u'a'
map_obj.slug = 'a'
try:
DBSession.add(map_obj)
DBSession.flush()
except Exception:
return {'success': False}
return {
'id': map_obj.id,
'success': True
}
This results in a InvalidRequestError, which cannot be catched, even with
an except Exception.
04:34:25,180 ERROR [waitress] Exception when serving /exception_test
Traceback (most recent call last):
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/waitress/channel.py",
line 336, in service
task.service()
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/waitress/task.py",
line 169, in service
self.execute()
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/waitress/task.py",
line 388, in execute
app_iter = self.channel.server.application(env, start_response)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/paste/translogger.py",
line 69, in __call__
return self.application(environ, replacement_start_response)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/pyramid/router.py",
line 242, in __call__
response = self.invoke_subrequest(request, use_tweens=True)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/pyramid/router.py",
line 217, in invoke_subrequest
response = handle_request(request)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/pyramid/tweens.py",
line 21, in excview_tween
response = handler(request)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/pyramid_tm/__init__.py",
line 101, in tm_tween
reraise(*exc_info)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/pyramid_tm/__init__.py",
line 90, in tm_tween
manager.commit()
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/transaction/_manager.py",
line 111, in commit
return self.get().commit()
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/transaction/_transaction.py",
line 280, in commit
reraise(t, v, tb)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/transaction/_transaction.py",
line 271, in commit
self._commitResources()
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/transaction/_transaction.py",
line 417, in _commitResources
reraise(t, v, tb)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/transaction/_transaction.py",
line 394, in _commitResources
rm.tpc_vote(self)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/zope/sqlalchemy/datamanager.py",
line 103, in tpc_vote
self.tx.commit()
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/sqlalchemy/orm/session.py",
line 390, in commit
self._assert_active(prepared_ok=True)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/sqlalchemy/orm/session.py",
line 214, in _assert_active
% self._rollback_exception
InvalidRequestError: This Session's transaction has been rolled back due to
a previous exception during flush. To begin a new transaction with this
Session, first issue Session.rollback(). Original exception was:
(psycopg2.IntegrityError) duplicate key value violates unique constraint
"uq_maps_user_id"
DETAIL: Key (user_id, slug)=(1, a) already exists.
If I put a DBSession.rollback() in the exception block, it results in:
04:37:58,625 ERROR [waitress] Exception when serving /exception_test
Traceback (most recent call last):
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/waitress/channel.py",
line 336, in service
task.service()
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/waitress/task.py",
line 169, in service
self.execute()
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/waitress/task.py",
line 388, in execute
app_iter = self.channel.server.application(env, start_response)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/paste/translogger.py",
line 69, in __call__
return self.application(environ, replacement_start_response)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/pyramid/router.py",
line 242, in __call__
response = self.invoke_subrequest(request, use_tweens=True)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/pyramid/router.py",
line 217, in invoke_subrequest
response = handle_request(request)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/pyramid/tweens.py",
line 21, in excview_tween
response = handler(request)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/pyramid_tm/__init__.py",
line 101, in tm_tween
reraise(*exc_info)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/pyramid_tm/__init__.py",
line 90, in tm_tween
manager.commit()
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/transaction/_manager.py",
line 111, in commit
return self.get().commit()
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/transaction/_transaction.py",
line 280, in commit
reraise(t, v, tb)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/transaction/_transaction.py",
line 271, in commit
self._commitResources()
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/transaction/_transaction.py",
line 417, in _commitResources
reraise(t, v, tb)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/transaction/_transaction.py",
line 394, in _commitResources
rm.tpc_vote(self)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/zope/sqlalchemy/datamanager.py",
line 103, in tpc_vote
self.tx.commit()
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/sqlalchemy/orm/session.py",
line 390, in commit
self._assert_active(prepared_ok=True)
File
"/Users/user/.virtualenvs/maphub_web/lib/python2.7/site-packages/sqlalchemy/orm/session.py",
line 223, in _assert_active
raise sa_exc.ResourceClosedError(closed_msg)
ResourceClosedError: This transaction is closed
Moreover, the weird part is that it all seems to depend on seemingly
meaningless (to me at least) order of the queries:
Moving the query(Map) to be before user.tutorial_done
user = DBSession.query(User).filter(User.id == 1).first()
DBSession.query(Map).first()
user.tutorial_done = True
Results in the correct, catchable IntegrityError.
However, removing the .filter() part makes it broken again:
user = DBSession.query(User).first()
DBSession.query(Map).first()
user.tutorial_done = True
What is happening here? I'm totally confused. Is this a bug in ZTE or
SQLAlchemy? How can I possibly run into an uncatchable exception in a view,
and if I do, what am I supposed to do?
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