I got it, thanks all!
It was a lack of space between property name and operator in filter()
method. It led to empty result (but not an exception???)
-Dmitry
On Apr 21, 11:52 am, Mark Wolgemuth <fuma...@gmail.com> wrote:
> I think your second one may be "working" because using the string
> substitution is causing an unexpected value to appear in the query
> that still is accepted by the engine. You should generate a log entry
> before the query to see what passing the id to %s is actually giving
> you.
>
> On Apr 21, 8:10 am, Dmitry Kachaev <dmitry.kach...@gmail.com> wrote:
>
> > Yes, Checkpoint class is defined in models package.
>
> > bus.checkpoint_id has value (in both cases, I can see it in debug
> > messages)
>
> > -Dmitry
>
> > On Apr 21, 8:04 am, 风笑雪 <kea...@gmail.com> wrote:
>
> > > Why you use models.Checkpoint?
> > > Is the Checkpoint class defines in models package/module?
>
> > > If not, use this:
> > > point_old = Checkpoint.all().filter("checkpoint_id=",
> > > bus.checkpoint_id).get()
>
> > > And for the "'NoneType' object has no attribute 'checkpoint_id'", you
> > > should
> > > check bus.checkpoint_id to ensure it's not None.
>
> > > 2009/4/21 Dmitry Kachaev <dmitry.kach...@gmail.com>
>
> > > > I use following construction to lookup records from datastore:
>
> > > > point_old=models.Checkpoint.all().filter("checkpoint_id
> > > > =", bus.checkpoint_id).get()
>
> > > > It works fine in most scenarios, but sometime I'm getting error like
> > > > this:
>
> > > > 'NoneType' object has no attribute 'checkpoint_id'
> > > > Traceback (most recent call last):
> > > > File "/base/python_lib/versions/1/google/appengine/ext/webapp/
> > > > __init__.py", line 501, in __call__
> > > > handler.get(*groups)
> > > > File "/base/data/home/apps/xxx/1.332943763447248076/tasks/
> > > > busupdate.py", line 22, in get
> > > > self.update(bus)
> > > > File "/base/data/home/apps/xxx/1.332943763447248076/tasks/
> > > > busupdate.py", line 45, in update
> > > > self.check_points(bus)
> > > > File "/base/data/home/apps/xxx/1.332943763447248076/tasks/
> > > > busupdate.py", line 86, in check_points
> > > > logging.debug("found old checkpoint: %s" %
> > > > (point_old.checkpoint_id))
> > > > AttributeError: 'NoneType' object has no attribute 'checkpoint_id'
>
> > > > Basically, get() returns None, but record I looked up is definitely in
> > > > datastore.
>
> > > > I figured out and replaced this look up call with equivalent GQL call:
>
> > > > point_old = db.GqlQuery("SELECT * FROM Checkpoint WHERE
> > > > checkpoint_id = %s" % (bus.checkpoint_id)).get()
> > > > #point_old=models.Checkpoint.all().filter("checkpoint_id
> > > > =", bus.checkpoint_id).get()
>
> > > > What is wrong? Those constructs should behave the same way, but they
> > > > don't. Commented one is not returning a record, when GQL is returning
> > > > single record, just fine.
>
> > > > Thanks,
> > > > Dmitry
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