Data retrieval template tag

from django import template

from community.models import *

register = template.Library()

def data_template_tag(data_func, *args, **kwargs):
    """
    A decorator for creating template tags that put data into
    the template context.

    data_func is a function that returns the data you want to
    put into the context (normally a queryset).

    Usage:

    @register.tag
    @data_template_tag
    def get_my_data():
        return MyData.objects.filter(...)

    In the template:

    {% get_my_data as my_data %}
    
    Arguments are also supported.

    @register.tag
    @data_template_tag
    def get_my_data(user):
        return MyData.objects.filter(user=user)

    {% get_my_data user as my_data %}
    """
    def wrapped(parser, token):
        bits = list(token.split_contents())

        args = []
        name = None
        next_as = False 
        for bit in bits[1:]:
            if bit == "as":
                next_as = True
            elif next_as:
                name = bit
                break
            else:
                args.append(bit)
                 
        if not name:
            raise TemplateSyntaxError("%r expected format is '%s *args as <name>'" %
                                      (bits[0], bits[0]))
        return DataNode(data_func, args, name)

    #Fix the name so that @register.tag works
    wrapped.__name__ = data_func.__name__
    return wrapped 

class DataNode(template.Node):
    def __init__(self, data_func, args, var_name):
        self.data_func = data_func 
        self.args = args
        self.var_name = var_name

    def __repr__(self):
        return "<DataNode>"

    def render(self, context):
        args = [template.resolve_variable(arg, context) for arg in self.args]
        context[self.var_name] = self.data_func(*args)
        return u""