How to put timedelta in django model?

user_80500 0
Viewed 43664

With inspectdb I was able to get a "interval" field from postgres into django. In Django, it was a TextField. The object that I retrieved was indeed a timedelta object!

Now I want to put this timedelta object in a new model. What's the best way to do this? Because putting a timedelta in a TextField results in the str version of the object...

django
8 Answers

You can trivially normalize a timedelta to a single floating-point number in days or seconds.

Here's the "Normalize to Days" version.

float(timedelta.days) + float(timedelta.seconds) / float(86400)

You can trivially turn a floating-point number into a timedelta. 

>>> datetime.timedelta(2.5)
datetime.timedelta(2, 43200)

So, store your timedelta as a float.

Here's the "Normalize to Seconds" version.

timedelta.days*86400+timedelta.seconds

Here's the reverse (using seconds)

datetime.timedelta( someSeconds/86400 )
SLott_106610

There is a workaround explained here. If you're using Postgresql, then multiplying the result of F expression with timedelta solves the problem. For example if you have a start_time and a duration in minutes, you can calculate the end_time like this:

YourModel.objects.annotate(
    end_time=ExpressionWrapper(F('start_time') + timedelta(minutes=1) * F('duration'), output_field=DateTimeField())
)
user_90700160
Related