Say I have a class in model
class Post(models.Model): time_posted = models.DateTimeField(auto_now_add=True, blank=True) def get_time_diff(self): timediff = timediff = datetime.datetime.now() - self.time_posted print timediff # this line is never executed return timediff
I defined a get_time_diff to get the time difference from the time when the Post is posted up to now, according to the document, the DateTimeField should be able to be converted to datetime automatically, is that correct? Why the print statement is never being run? How can you extract the time difference?
Beside, if you get a time difference, is there an easy way to convert the time difference to an integer, like the number of seconds of the total time.
Your code is already working; a
datetime.timedelta object is returned.
To get the total number of seconds instead, you need to call the
.total_seconds() method on the resulting
from django.utils.timezone import utc def get_time_diff(self): if self.time_posted: now = datetime.datetime.utcnow().replace(tzinfo=utc) timediff = now - self.time_posted return timediff.total_seconds()
.total_seconds() returns a
float value, including microseconds.
Note that you need to use a timezone aware
datetime object, since the Django
DateTimeField handles timezone aware
datetime objects as well. See Django Timezones documentation.
.total_seconds() (with naive
datetime objects, but the principles are the same):
>>> import datetime >>> time_posted = datetime.datetime(2013, 3, 31, 12, 55, 10) >>> timediff = datetime.datetime.now() - time_posted >>> timediff.total_seconds() 1304529.299168
Because both objects are timezone aware (have a
.tzinfo attribute that is not
None), calculations between them take care of timezones and subtracting one from the other will do the right thing when it comes to taking into account the timezones of either object.