David Janes' Code Weblog

November 28, 2008

Djolt – Django-like Templates

djolt,pybm,python,work · David Janes · 4:34 pm ·

Djolt is a reimplementation of Django’s template language in Python. Why do this?

  • I like the Django template language
  • I wanted something that small and independent of Django
  • I wanted something that will work with WORK paths (this was the real deal breaker for using Django)
  • I wanted something that I could take and reimplement in Javascript and maybe Java too
  • Some template engines, Cheetah for example, are far too heavy for the kind of light-weight applications I have in mind; note that I’ve had great success with Cheetah in the past
  • Some template engines, such as that in Python 2.6, are for too underfeatured

However, if you’re really looking for the whole Django template experience and don’t want to use Djolt, just start here.

How do I get it?

Djolt is packaged as part of the pybm library.

How do I use it?

import djolt

t = djolt.Template("""
<ul>
{% for name in names %}
<li>{{ name }}</li>
{% endfor %}
</ul>
""")
print t.Render({
    "names" : [ "Johnny", "Jack", "Ray", "Mary & Sam", ]
})

Which gives the results:

<ul>
<li>Johnny</li>
<li>Jack</li>
<li>Ray</li>
<li>Mary &amp; Sam</li>
</ul>

Note the “autoescaping” of the & character.

What tags does it define?

  • autoescape/endautoescape
  • if/else/endif
  • equal/endequal
  • for/endfor
  • notequal/notendequal

It does not implement blocks.

What filters does it define?

  • add
  • cut
  • default (see otherwise below)
  • default_if_none
  • divisibleby
  • first
  • join
  • last
  • length
  • length_is
  • linebreaks
  • lower
  • pluralize
  • random
  • safe (respecting all the Django autoescape rules)
  • slug
  • upper

Unimplemented filters are due to laziness and will be done “on demand”. We also introduce a few new filters:

  • jslug – like slug, but more Javascript friendly
  • otherwise – like default, except the empty string/empty values trigger the filter also

Are their differences between Djolt and Django templates?

  • Djolt tags suck up whitespace if they’re on a line by themselves
  • If Djolt cannot resolve a variable, it resolves to the appropriate “empty” value (as opposed to failing). This is keeping in line with WORK philosophy

Beyond that you should be able to use most Django template examples (that don’t use block/implements) as-is.

Is it extensible?

Yes. You can add your own tags and filters by following the examples in code (djolt_nodes.py and djolt_filters.py respectively).

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