Re: Combining queries? A "join" in Python?

On Sep 1, 4:48 am, Stuart <stu...@bistrotech.net> wrote:
> On Aug 30, 12:10 pm, graeme <graeme.piete...@gmail.com> wrote:
>
>
>
> > What my query does is give me a list of subcategories, ordered by
> > category, and then by the number of places in the category, and
> > annotates each subcategory with the number of places in it.
>
> > Having a single category model might simplify the query, but as I want
> > the page to show something like:
>
> > CATEGORY
> > Subcategory One
> > Subcategory Two
> > CATEGORY TWO
> > Subcategory Three
> > etc.
>
> I would take a different approach to build this structure. Take
> advantage of the object model. You could get a list of root categories
> and send those off to a function (probably a template filter) that
> builds the html representation you want. If you have the root
> categories, you have everything you need.
>
> root_cats = Category.objects.filter(parent__isnull=True) # gets root
> categories
> for cat in root_cats: # iterate thru root categories
>    print "%s (%s)" % (cat.name, cat.texts.count()) # CATEGORY (2)
>    for t in cat.texts.all(): # iterate thru texts that belong to each
> root category
>       print t
>    for c in cat.children.all(): # iterate thru child categories (one
> level down from the root)
>       print "%s (%s)" % (c.name, c.texts.count()) # Subcategory One
> (3)
>
> Rework that code to traverse all the way to the bottom (smarter
> iteration or maybe recursion) and you've got what you need without a
> complicated query.

Thanks Stuart, that was a huge help, although perhaps not in the way
you expected.

I used the same approach with my existing models, and it works fine.
The code is shorter, the queries are simpler, my template is simpler
and it is a lot faster.

I am currently have HTML snippets hard coded in the view which is not
nice. I am not inclined to write filter or template tag, so I am
thinking of moving the HTML snippets in the view into templates and
using render_to_string to return strings that are then passed to the
main template.

>
> --Stuart

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