Django - TimeField difference

Question

I would like to compare two time fields to get the difference in hours and minutes.

class Labor(models.Model):
    id = models.AutoField(primary_key=True)
    start_hour = models.TimeField(null=True)
    end_hour = models.TimeField(null=True)

    def hours(self):
        return self.end_hour - self.start_hour 

But, if try to use the hours method, django throws this exception:

unsupported operand type(s) for -: 'datetime.time' and 'datetime.time'

I would like that the difference returns me something like this:

10:00 ~ 11:30 = 1:30

11:30 ~ 11:45 = 0:15

How could I do that?

Answer 1

First make the fields as DateTimeField as @Chiefir mentioned, this gives you a datetime object.

then,

def hours(self):
        c = self.end_time - self.start_time
        print(c.seconds) 
        # Write your logic to convert seconds to hours.

Answer 2

If you don't want to make your fields DateTimeFields, you can just do some quick math (assuming your times are in the same day).

def hours(self):
    end_minutes = self.end_hour.hour*60 + self.end_hour.minute
    start_minutes = self. start_hour.hour*60 + self.start_hour.minute
    return (end_minutes - start_minutes) / 60

That will return a float, but you can always round the value. You may also want to check to make sure self.end_hour is greater than self.start_hour.