django template tags

custom_tags

from django import template

register = template.Library()


# ifinlist
class IfInListNode(template.Node):
	def __init__(self, nodelist_true, nodelist_false, item, list):
		self.nodelist_true = nodelist_true
		self.nodelist_false = nodelist_false
		self.item = template.Variable(item)
		self.list = template.Variable(list)

	def render(self, context):
  		try:
			item = self.item.resolve(context)
			list = self.list.resolve(context)
  		except template.VariableDoesNotExist:
  			return ''

		try:
			if item in list:
				return self.nodelist_true.render(context)
			else:
				 return self.nodelist_false.render(context)
		except TypeError:
			return ''

@register.tag
def ifinlist(parser, token):
 	try:
 		tag_name, item, list = token.split_contents()
 	except ValueError:
 		raise template.TemplateSyntaxError, "%r tag requires two arguments" % token.contents.split()[0]

	nodelist_true = parser.parse(('else', 'endifinlist'))
	token = parser.next_token()

	if token.contents == 'else':
		nodelist_false = parser.parse(('endifinlist',))
		parser.delete_first_token()
	else:
		nodelist_false = template.NodeList()

	return IfInListNode(nodelist_true, nodelist_false, item, list)


# ifnotinlist
class IfNotInListNode(template.Node):
	def __init__(self, nodelist_true, nodelist_false, item, list):
		self.nodelist_true = nodelist_true
		self.nodelist_false = nodelist_false
		self.item = template.Variable(item)
		self.list = template.Variable(list)

	def render(self, context):
  		try:
			item = self.item.resolve(context)
			list = self.list.resolve(context)
  		except template.VariableDoesNotExist:
  			return ''

		try:
			if item not in list:
				return self.nodelist_true.render(context)
			else:
				 return self.nodelist_false.render(context)
		except TypeError:
			return ''

@register.tag
def ifnotinlist(parser, token):
 	try:
 		tag_name, item, list = token.split_contents()
 	except ValueError:
 		raise template.TemplateSyntaxError, "%r tag requires two arguments" % token.contents.split()[0]

	nodelist_true = parser.parse(('else', 'endifnotinlist'))
	token = parser.next_token()

	if token.contents == 'else':
		nodelist_false = parser.parse(('endifnotinlist',))
		parser.delete_first_token()
	else:
		nodelist_false = template.NodeList()

	return IfNotInListNode(nodelist_true, nodelist_false, item, list)