Custom Tags

from django import template
register = template.Library()


#####################################################################
# filters
######################################################################

@register.filter
def extra(value,args):
        """  Return value with replaced characters of args to 0 
        extra = name of filter
        value = value of variable that filter was applied to
        args = arguments passed with filter """
	return value.replace(args,str(0))


# template

{% load "something" %}
{{ somevariable|extra:"0" }}



# convert all to string befor processing

from django.template.defaultfilters import stringfilter

@register.filter
@stringfilter
def lower(value):
    return value.lower()




####################################################################
# simple_tag
####################################################################

@register.simple_tag
def do_current_time(word, word2):
	var = word + word2
	return var.lower()


# template

{% do_current_time "He Loves WORD" " Peace And LOVE" %}




######################################################################
# Tags
#####################################################################

from django import template
import datetime

@register.tag
def do_current_time(parser, token):
    """ 
       parser = template parser object
       token = raw contents of the tag ( 'current_time "%Y-%m-%d %I:%M %p"' )
       split_contents() = separates on spaces while keeping quoted strings together
       template.TemplateSyntaxError = helpful messages, for any syntax error.
    """
    try:
        tag_name, format_string = token.split_contents()
    except ValueError:
        raise template.TemplateSyntaxError, "%r tag required" % token.contents.split()[0]
    if not (format_string[0] == format_string[-1] and format_string[0] in ('"', "'")):
        raise template.TemplateSyntaxError, "%r tag's argument should be in quotes" % tag_name
    return CurrentTimeNode(format_string[1:-1])



class CurrentTimeNode(template.Node):
    def __init__(self, format_string):
        self.format_string = format_string
    def render(self, context):
        return datetime.datetime.now().strftime(self.format_string)




##############################################################################
# inclustion_tag
##############################################################################


@register.inclusion_tag('left_menu.html')
def left_menu():
	left_menu = Menu.objects.filter(side='left',page__name='news')
	return {'left_menu':left_menu}



# with context

@register.inclusion_tag('link.html', takes_context=True)
def jump_link(context):
    return {
        'link': context['home_link'],
        'title': context['home_title'],
        'user': context['user'],
    }



@register.inclusion_tag('profile.html', takes_context=True)
def some_tag(context, table):
    return {
        'table': table.objects.all()
        'user': context['user'],
    }


# template

1 {% left_menu %}
2 {% jump_link %}
3 {% some_tag Profile %}