Jorge - that is exactly what I was after - thanks very much! I don't
have too many categories, and don't expect there to be more than 100
or so - so the convenience outweighs the overhead.
This way, I'm even able to add filters before doing the iteration.
-Phil
On 12/07/06, Jorge Gajon <[EMAIL PROTECTED]> wrote:
>
> Hi,
>
> If there are not a lot of categories (i.e. a thousand or more), you
> could iterate over all categories and filter only those that have a
> photo_set of 1 or more. For example in a view you could do:
>
> categories = [c for c in Category.objects.all() if c.photo_set.count()]
>
> You could say that it is not very optimal because you are fetching all
> the categories. But I personally wouldn't worry about it if there are
> not many categories.
>
> Cheers,
> Jorge
>
> On 7/12/06, Phil Powell <[EMAIL PROTECTED]> wrote:
> >
> > Hi - I've got a bit of a conundrum.
> >
> > I have two models, Category and Photo which look something like this:
> >
> > class Category(models.Model):
> > title = models.CharField(maxlength=80)
> > slug = models.SlugField(prepopulate_from=("title",))
> >
> > class Photo(models.Model):
> > catalogue_number = models.IntegerField(maxlength=80)
> > slug = models.SlugField(prepopulate_from=("catalogue_number",))
> > category = models.ForeignKey(Category,blank=True)
> >
> > There is a one-to-many relationship defined so that a Photo can be
> > assigned a Category.
> >
> > Now, what I want to be able to do is get a list of Categories, but
> > ONLY those Categories which have been assigned to one or more Photos.
> >
> > I can think of plenty of ugly ways to work around this, but wondered
> > whether anyone had a graceful solution?
> >
> > -Phil
> >
> > >
> >
>
> >
>
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