navigation example for a templatetag

mytags.py

from django.template import Node, Library, Variable
from myapp.models import Whatever

register  = Library()


class NavigationNode(Node):

    def __init__(self, user, varname):
        # this is a variable in the template so we need to resolve later
        self.user = Variable(user)
        self.varname  = varname

    def render(self, context):
        # resolve that user
        user = self.user.resolve(context)
        # get the nav bits
        whatevers = Whatever.objects.filter(user=user)
        # set it in the context
        context[self.varname] = whatevers
        # Nodes need to return a blank string
        return ''


@register.filter
def get_nav_for_user(parser, token):
    """
    split the token.cotents up into a list
    
    get_nav_for_user request.user as nav 
    
    will become
    
    ['get_nav_for_user', 'request.user' 'as' 'nav']
    
    """ 
    bits = token.contents.split()
    # now return the node using bits[1] - request.user
    # and bits[3] - nav
    return NavigationNode(bits[1], bits[3])