On Mon, Feb 23, 2009 at 7:33 PM, Malcolm Tredinnick < malc...@pointy-stick.com> wrote:
> > On Mon, 2009-02-23 at 16:21 -0800, bendavis78 wrote: > > I have products within categories. The url for a product is /store/ > > category-slug/product-slug. My question is about the best way to get > > the url for this product while looping through a product listing > > page. My view simply defines a context variable called products, > > assigned to the results of a .filter() call. > > > > Given these models: > > > > def Category(models.Model): > > name = models.CharField(max_length=255) > > slug = models.SlugField() > > > > def Product(models.Model): > > name = models.CharField(max_length=255) > > slug = models.SlugField() > > category = models.ForeignKey(Category) > > > > def get_absolute_url(self): > > category_slug = Category.objects.get(id=self.category_id).slug > > return "/%s/%s" % (category_slug, self.slug) > > > > > > You can see that calling get_absolute_url() while looping through a > > list of products in a template will require an extra query to be sent > > to the server for each iteration of a product, which is clearly not > > ideal. My other option to use .values() in the view to select out > > the category slug along with all the other columns on the product, > > but this doesn't seem ideal either. > > You can certainly simplify get_absolute_url() a bit: > > def get_absolute_url(self): > category_slug = self.category__slug > return "/%s/%s" % (category_slug, self.slug) > > In this way, if it needs to, Django will look up the related model. > However, if you've retrieved a queryset using select_related(), the > Category instances will already be present and no extra query will be > involved. If you're doing a loop and needing get_absolute_url, you then > have to remember to always use select_related(). > > You could even make that automatic by creating a custom default manager > whose get_query_set() method looked like this: > > def get_query_set(self): > return super(MyManager, > self).get_query_set().select_related() > > and it would always happen. > > Regards, > Malcolm > > > > > > Malcolm, I think it's a little early. self.category__slug? ;) That's self.category.slug unless I've missed something enormous. Alex -- "I disapprove of what you say, but I will defend to the death your right to say it." --Voltaire "The people's good is the highest law."--Cicero --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
