On 20 août, 00:32, widoyo <wid...@gmail.com> wrote:
> Try to add function 'quota_ore' below.
>
> On Aug 19, 3:03 am, djnubbio <giuseppe.nati...@gmail.com> wrote:> Sorry for
> wasting your preciuose time. I'm very newby in django.
>
> > I have de following
>
> > class Commessa(models.Model):
> > commessa = models.CharField(max_length=20)
> > quota_oraria=models.DecimalField(max_digits=5, decimal_places=2)
> > ...
>
> def quota_ore(self):
> self.quota_oraria * sum([d.ore for d in self.diario_set.all()])
Actually,
def quota_ore(self):
return self.quota_oraria * sum([d.ore for d in
self.diario_set.all()])
would work better... At least it would return something instead of
None !-)
Then you could avoid useless model instances creation, as well as the
temporary list:
def quota_ore(self):
return self.quota_oraria *
sum(self.diario_set.values_list('ore', flat=True))
But still : sum() is a standard SQL aggregation function, so it
probably (yes, that's an understatement) would be faster and cheaper
to just let the SQL engine do the hard work:
from django.db.models import Sum
def quota_ora(self):
return self.quota_oraria * self.diario_set.aggregate(Sum('ore'))
['sum__ore']
NB : not tested but according to the FineManual and my it should
JustWork(tm).
HTH
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