What are some useful non-built-in Django tags?

I'm relatively new to Django and I'm trying to build up my toolbox for future projects. In my last project, when a built-in template tag didn't do quite what I needed, I would make a mangled mess of the template to shoe-horn in the feature. I later would find a template tag that would have saved me time and ugly开发者_如何学C code.

So what are some useful template tags that doesn't come built into Django?

I'll start.

http://www.djangosnippets.org/snippets/1350/

Smart {% if %} template tag

If you've ever found yourself needing more than a test for True, this tag is for you. It supports equality, greater than, and less than operators.

Simple Example

{% block list-products %}
    {% if products|length > 12 %}
        <!-- Code for pagination -->
    {% endif %}

    <!-- Code for displaying 12 products on the page -->

{% endblock %}

smart-if. Allows normal if x > y constructs in templates, among other things.

A better if tag is now part of Django 1.2 (see the release notes), which is scheduled for release on March 9th 2010.

James Bennet's over-the-top-dynamic get_latest tag

edit as response to jpartogi's comment

class GetItemsNode(Node):
    def __init__(self, model, num, by, varname):
        self.num, self.varname = num, varname
        self.model = get_model(*model.split('.'))
        self.by = by

    def render(self, context):
        if hasattr(self.model, 'publicmgr') and not context['user'].is_authenticated():
            context[self.varname] = self.model.publicmgr.all().order_by(self.by)[:self.num]
        else:
            context[self.varname] = self.model._default_manager.all().order_by(self.by)[:self.num]
        return  ''

<div id="news_portlet" class="portlet">
{% get_sorted_items cms.news 5 by -created_on as items %}
{% include 'snippets/dl.html' %}
</div>
<div id="event_portlet" class="portlet">
{% get_sorted_items cms.event 5 by date as items %}
{% include 'snippets/dl.html' %}
</div>

I call it get_sorted_items, but it is based on James' blog-post

In come case {% autopaginate queryset %} (http://code.google.com/p/django-pagination/) is useful. For example:

#views.py
    obj_list = News.objects.filter(status=News.PUBLISHED)
    # do not use len(obj_list) - it's evaluate QuerySet
    obj_count = obj_list.count()

#news_index.html
    {% load pagination_tags %}
    ...
    # do not use {% if obj_list %}
    {% if obj_count %}
        <div class="news">
        <ul>
        {% autopaginate obj_list 10 %}
        {% for item in obj_list %}
            <li><a href="...">{{ item.title }}</a></li>
        {% endfor %}
        </ul>
        </div>
        {% paginate %}
    {% else %}
        Empty list
    {% endif %}

Note, that obj_list must be lazy - read http://docs.djangoproject.com/en/dev/ref/models/querysets/#id1