[Answered ]-Django custom methods in templates and DB queries

Add a method to Company:

import datetime

...

class Company(Model):

    ...

    def is_open(self):
        today_hours = self.opening_times.filter(weekday=datetime.datetime.today().weekday())[0] # you may want to add code to make sure that there is an entry for this weekday
        if datetime.datetime.now().time() > today_hours.fromHour and datetime.datetime.now().time() < today_hours.toHour:
            return True
        else:
            return False

You will then be able to call this using {{ company.is_open }} in your templates.

Unfortunately, you will not be able to query on this or order by it in your database calls. However, you can sort it after the query is done:

companies = sorted(Company.objects.all(), key=lambda c: c.is_open(), reverse=True)