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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