Question

This is a very noobish question, so I apologize in advance!

I have two time stamps for start and end of the event. They are stored in as datetime.datetime in UTC. What I need to do is figure out the duration of the event.

I tried subtracting one from the other, but receive error:

Traceback (most recent call last):
02.
File '/base/python_lib/versions/1/google/appengine/ext/webapp/__init__.py', line 509, in __call__
03.
handler.post(*groups)
04.
File '/base/data/home/apps/.../3.340324527833140591/main.py', line 441, in post
05.
call_record.Duration = call_record.CallStartTime - call_record.CallEndTime
06.
File '/base/python_lib/versions/1/google/appengine/ext/db/__init__.py', line 472, in __set__
07.
value = self.validate(value)
08.
File '/base/python_lib/versions/1/google/appengine/ext/db/__init__.py', line 2322, in validate
09.
(self.name, self.data_type.__name__))
10.
BadValueError: Property Duration must be a datetime
11.

CallStartTime, CallEndTime and Duration are all db.DateTimeProperty() types in GAE.

I had previously used django timesince to display the duration, but I need to do some additional calculations to figure out avg. duration of the events.

Any suggestions or pointers at what additional info might help are greatly appreciated!

Answer 1

Subtracting one datetime from another will give you a timedelta. You can use that to create another datetime if you need to by adding it to or subtracting it from another datetime object.

How can you represent a duration with a single datetime object, though?