Extra template filters for django : accessing dict through key in template

#file : myApp/templatetags/appName_extras.py
from django import template

register = template.Library()

def key(d, key_name):
    try:
        value = d[key_name]
    except KeyError:
        from django.conf import settings

        value = settings.TEMPLATE_STRING_IF_INVALID

    return value
key = register.filter('key', key)