On Monday, 10 October 2011 19:14:51 UTC+1, eyscooby wrote:
>
>
>
> On Oct 5, 3:11 am, Daniel Roseman <dan...@roseman.org.uk> wrote:
> > On Wednesday, 5 October 2011 01:27:54 UTC+1, eyscooby wrote:
> >
> > > new to django/python developement, can't get this one figured out.
> >
> > > I have a model that has a couple DateFields (issued_date &
> > > completion_date), and I'm trying to return a value with the difference
> > > of the two on each entry that is complete, and then if it isn't
> > > completed yet, show the amount of days since it was issued.
> > > I am using the Admin interface and what I have in the model is
> > > this....
> >
> > > models.py
> > > class RequestTicket(models.Model):
> > > . . .
> > > issued_date = DateField()
> > > completed_date = DateField(blank=True, null=True)
> >
> > > def days_old(self):
> > > complete = RequestTicket.object.filter(completion_date__isnull=False)
> > > for ticket in complete:
> > > return ticket.completion_date - ticket.issued_date
> > > return date.today() - self.issued.date
> > > days_old.short_discription = 'Days Old'
> >
> > > what i get returned is if the first entry was completed within 2 days
> > > (issued=9/14, completed=9/16), all entries after that get 2 days, even
> > > if there is no completion date.
> > > If i use 'self.object.filter(completion_date__isnull=False)', I get a
> > > NONE answer on all entries
> > > If I don't filter for just completed entries I get an error trying to
> > > subtract NoneType field with DateField, i guess that might be from the
> > > NULL setting.
> > > Any help, advice would be great, or if i need to post in another area.
> >
> > > Django version 1.2
> >
> > > thanks
> > > Kenney
> >
> > OK, there are a few things wrong with your `days_old` function.
> >
> > Firstly, it operates on a queryset, not an instance, so it should be a
> > method of the Manager, not the Model.
> >
> > Secondly, you can't return multiple times like that. You can only return
> > once from a function. You need to build up a list of values, and return
> that
> > - or set the attribute on each element of the queryset.
> > --
> > DR.- Hide quoted text -
> >
> > - Show quoted text -
>
> DR.
> would creating a manager something like this work with a list??
>
> class RequestTicketManager(models.Manager):
> def datecalc(self):
> complete_list =
> list(self.objects.filter(competion_date__isnull=False))
> for day in complete_list:
> return day.competion_date - day.issued_date
>
> I then put "objects = RequestTicketManager()" in my model
>
> thanks for you help,
You're almost there, but you're still trying to return multiple times. The
last few lines should be:
for day in complete_list:
day.days_old = day.completion_date - day.issued_date
return complete_list
Actually, since that calculation is fairly trivial, you could probably do it
as an instance method on the model class:
class RequestTicket(models.Model):
...
def days_old(self):
return self.completion_date - self.issued_date
The difference between this and the method you first proposed is that this
only acts on a single instance at a time - so you'll need to get the
queryset of completed items in your view in the normal way, then when you
iterate through in the template you can just do {{ ticket.days_old }}.
--
DR.
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