Django hierarchical model list

Question

This should be simple, but I'm shredding my hair just trying to think how to tackle it!

I have a navigation menu down the side of my site that is used to pick products. It's formatted like so:

Every product belongs in a 'list' (clicking on the list sends to you a page with the list of products).
Every list belongs in a 'category' (clicking on the category uses jquery to expand out a list beneath it when clicked, but that's besides the point)
Every Category belongs in a 'Category Group' that separates the categories into distinct groups depending on what area of the business you're dealing with)

In simpler terms, products belong in a list, which belong in a category, which belongs in a category group. They are all one-to-many relationships.

I need to pass this from my view to my template in such a way as I can render a nested list in HTML for jquery to make pretty. Something like:

<ul>
    <li>Category Group</li>
    <ul>
        <li>Category</li>
        <ul>
            <li>List</li>
            <li>List</li>
            <li>List</li>
        </ul>
        <li>Category</li>
        <ul>
            <li>List</li>
            <li>List</li>
            <li>List</li>
        </ul>
    </ul>
    <li>Category Group</li>
    <ul>
        <li>Category</li>
        <ul>
            <li>List</li>
            <li>List</li>
            <li>List</li>
        </ul>
        <li>Category</li>
        <ul>
            <li>List</li>
            <li>List</li>
            <li>List</li>
        </ul>
    </ul>
</ul>

My issue is creating said hierarchical list to pass to the template so it can render that. I'm aware that I need to use Model.FK_set.all() to get say, a list of 'categories' in a 'category group', but I can't figure out how to create that list in the view in an appropriate way to send to the template. Any help? Python newbie, so still learning the ropes.

user90855 · Accepted Answer · 2011-11-18 04:21:38Z

5

When I see hierarchical or tree structures, I usually turn to mptt, a modified pre-order traversal tree. Google "django mptt" and you will find a large number of tutorials on using the django-mptt package.

answered Nov 18, 2011 at 4:21

user90855

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Acorn · Accepted Answer · 2011-11-18 05:11:55Z

Something like this would work:

from __future__ import with_statement
import os
from django.template import Context, Template

os.environ['DJANGO_SETTINGS_MODULE'] = 'settings'

menu = {
    'food':
        {'fruit':
            ['apple', 'orange'],
        'meat':
            ['beef', 'pork'],
        },
    'animals':
        {'mamals':
             ['cow', 'bear'],
         'reptiles':
             ['frog', 'newt'],
        },
}


with open('template.html', 'r') as infile:
    html = infile.read()
    t = Template(html)

    print t.render(Context({'menu': menu}))

Template:

<html>
<body>
<ul>
{% for name, cat_group in menu.items %}
<li>{{ name }}</li>
    <ul>
    {% for name, cat in cat_group.items %}
    <li>{{ name }}</li>
        <ul>
        {% for product in cat %}
        <li>{{ product }}</li>
        {% endfor %}
        </ul>
    {% endfor %}
    </ul>
{% endfor %}
</ul>
</body>
</html>

Alvin K. · Accepted Answer · 2011-11-18 03:49:01Z

0

A simple example of two category group.

a = [1,2]
b = [3,4,5]
c = [6,7]
d = [8]
item1 = [a,b]
item2 = [c,d]
mygroup = [item1,item2]

In django, you would have to use for loops to navigate:-

{% for items in mygroup %}
    // Group Category title here
    (% for list in items %}
        // Group title here
            (% for contents in list %}
                  // all the unit contents
[...dont forget to close your for loops...]

answered Nov 18, 2011 at 3:49

Alvin K.

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