On Mon, Feb 23, 2009 at 7:21 PM, bendavis78 <bendavi...@gmail.com> 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.
>
> I guess I'm so used to things being unbelievably elegant in django,
> I'm trying to convince myself there must be a better way! Is there?
>
> >
> First of all use self.category.slug so that you don't have to do an extra
query if the local cache is already populated. Next in places you know this
is giong to be an issue when you do your Product query add a call to
select_related('category') this will cause Django to preload the revelant
category for each Product, which will mean you don't do the extra sql query
to access self.category.
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
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