Django default=timezone.now() saves records using "old" time

python django django-timezone
Lucas Ou-Yang picture Lucas Ou-Yang · Nov 5, 2012 · Viewed 20.1k times · Source

This issue has been occurring on and off for a few weeks now, and it's unlike any that has come up with my project.

Two of the models that are used have a timestamp field, which is by default set to timezone.now().

This is the sequence that raises error flags:

  • Model one is created at time 7:30 PM

  • Model two is created at time 10:00 PM, but in the MySQL database it's stored as 7:30 PM!

Every model that is created has its time stamp saved under 7:30 PM, not the actual time, until a certain duration passes. Then a new time is set and all the following models have that new time... Bizzare

Some extra details which may help in discovering the issue:

I have a bunch of methods that I use to strip my timezones of their tzinfo's and replace them with UTC.

This is because I'm doing a timezone.now() - creationTime calculation to create a: "model was posted this long ago" feature in the project. However, this really should not be the cause of the problem.

I don't think using datetime.datetime.now() will make any difference either.

Anyway, thanks for the help!

Answer

Jamey Sharp picture Jamey Sharp · Nov 5, 2012

Just ran into this last week for a field that had default=date.today(). If you remove the parentheses (in this case, try default=timezone.now) then you're passing a callable to the model and it will be called each time a new instance is saved. With the parentheses, it's only being called once when models.py loads.

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