active links

filters.py

from django import template

register = template.Library()

@register.filter
def startswith(value, arg):
    """Usage, {% if value|starts_with:"arg" %}"""
    return value.startswith(arg)

nav.html

<ul class="nav">
  {% if user.is_authenticated %}
  {% url app1:view as view1 %}
  <li {% if request.path|startswith:view1 %}class="active"{% endif %}>
    <a href="{{ view1 }}">View1</a>
  </li>
  {% url app2:view as view2 %}
  <li {% if request.path|startswith:view2 %}class="active"{% endif %}>
    <a href="{{ view2 }}">View2</a>
  </li>
  {% endif %}
</ul>