How to write custom template tags in Django easily?

Question

Writing template tags isn't easy in Django and involves lots of boilerplate code. What is the least painful way to do it?

• Are there any libs for that?
• Are there any tricks that doesn't involve third-party apps?
• What is your way to do it?

(I will make this post a community wiki once I figure how to do it.)

Answer 1

---

There are some libs for that:

• django-templatetag-sugar

  Used it before. Makes everythings simpler, but I couldn't figure how to handle lots of optional arguments with it.

  Usage example::

  ''' {% example_tag for val as asvar %} '''
  
  @tag(register, [
      Constant("for"), Variable(),
      Optional([Constant("as"), Name()]),
      ])
  def example_tag(context, val, asvar=None):
      if asvar:
          context[asvar] = val
          return ""
      else:
          return val
  

• django-tagcon, abandoned by original author

• django-ttag, fork of django-tagcon

  These two look promising because of class-based approach and keyword arguments support (like {% output limit=some_limit|default:1 offset=profile.offset %})

  Example usage::

  class Welcome(ttag.Tag):
      ''' {% welcome current_user fallback "Hello, anonymous." %} '''
      user = ttag.Arg(positional=True)
      fallback = ttag.Arg(default='Hi!')
  
      def output(self, data)
          name = data['user'].get_full_name()
          if name:
              return 'Hi, %s!' % name
          return data['fallback']
  

---

Answer 2

Try django-classy-tags https://github.com/ojii/django-classy-tags

Answer 3

I use the fancy_tag decorator: http://pypi.python.org/pypi/fancy_tag

Very simple and powerful and it comes with good documentation.

Gets rid of all that boilerplate when you just want to assign the output of a template tag to a context variable. Also handles (variable length) arguments and keyword arguments.

Much easier to use than for example django-templatetag-sugar.

I haven't really needed anything else apart from the built in inclusion tag decorator.