How can I use a where clause with the sum of two fields

Question

I need to sum two fields in each record and then if that sum is greater than 0 select the record. Here's what the model looks like:

    class Location(models.Model):
        day1 = models.IntegerField(default=0)
        day2 = models.IntegerField(default=0)
        day3 = models.IntegerField(default=0)
        day4 = models.IntegerField(default=0)
        day5 = models.IntegerField(default=0)
        day6 = models.IntegerField(default=0)
        day7 = models.IntegerField(default=0)

and this is the query I have built

Location.objects.extra(select={'fieldsum': 'day1 + day2+ day3+ day4+ day5+ day6+ day7'},where=['fieldsum > 0'])

but it throws an error saying

django.db.utils.ProgrammingError: column "fieldsum" does not exist

Answer 1

You dont need add an extra field, just use F() Django built-in function and transform

day1 + day2+ day3+ day4+ day5+ day6+ day7 > 0 to day1 > 0 - day2 - day3 - day4 - day5 - day6 - day7

Then, your query should looks like this:

Location.objects.filter(day1__gt = 0 - F('day2') - F('day3') ..... -F('day7')  )