On Mon, Nov 12, 2012 at 10:06 AM, ozgur yilmaz <yelb...@gmail.com> wrote:
> Hi all,
>
> I have 4 classes and i want to build a get_absolute_url() for a class,
> querying other 3 classes. But i get "list index out of range" error
> for the FILTER row. Any ideas?
>
> class Aaa( models.Model ):
> ...
> ...
>
> class City( models.Model ):
> ...
> ...
>
> class Bbb( models.Model ):
> aaa = models.ForeignKey( Aaa )
> city = models.ForeignKey( City )
> ...
> ...
>
> class Ccc( models.Model ):
> aaa = models.ForeignKey( Aaa )
> ...
> ...
>
> def get_absolute_url(self):
>
> bbbs = Bbb.objects.filter( aaa = self.aaa )
>
> city = City.objects.get( id = bbbs[0].city.id )
>
> return "/" + city.name + "/" + str(self.id)
>
There may be something else too, but I think that you want get "bbbs" as
follows:
bbbs = self.aaa.bbb_set.all()
And you will need to check that bbbs is not empty before applying "[0]" to
it.
Also, once you have a bbb for sure, then get city by using
city = bbbs[0].city
In summary, something like:
def get_absolute_url(self):
if self.aaa.bbb_set.count() < 1:
return 'some_fixed_url_for_when_a_Ccc_has_no_bbbs' # Or raise a
404 or whatever
return '/%s/%d' % (self.aaa.bbb_set.all()[0].city.name, self.id)
Bill
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