Apr 16, 2012

Templates. New in Django 1.4


Continuing those series of tasty features in Django 1.4. It's templates and newly added templatetags this time. Many things improved in template logic now. Lets move on point by point...

Tag {% elif %}

For most of us it is almost killer feature of new Django 1.4. You will have simpler logic in your templates, if you have advanced logic there, of course. ;)

Key-value arguments for user tags

You can use key-value for tags along with old, positional, arguments, e.g.:

{% custom_tag 123 "test" thing.var text=msg|upper username=user.get_full_name %}

All of this implemented using common "args" and "kwargs":

@register.simple_tag
def custom_tag(a, b, *args, **kwargs):
    warning = kwargs['text']
    profile = kwargs['username']
    ...
    return ...

assignment_tag

Some tags are not built to output something in template, like simple_tag. They only have to change something in context during rendering of templates. (Built-in {% with %} tag, for e.g.).
You can make it output time like so:

{% get_common_time "%Y-%m-%d %I:%M %p" as object_time %}
The time is {{ object_time }}.

SO now you can use "assignment_tag", to make creating tags like this simpler:


@register.assignment_tag
def get_common_time(time_format):
    return datetime.datetime.now().strftime(time_format)


Translation marks in context

Django 1.3 appeared to have functions pgettext() and ngettext() to indicate context for translatable strings. It solved problem of short text phrases partially. It suited phrases that can have different translation depending on context. Now you can transfer it in template directly:

{% trans "Iurii" context "username" %}
{% trans "Do" context "verb" %}
{% blocktrans with name=user.username context "hello message" %}Hi {{ name }}{% endblocktrans %}

New {% static %} tag

You can now share STATICFILES_STORAGE with special tag:

{% load static from staticfiles %}
<img src="{% static "app/css/base.css" %}" />

Most profit will get those one's that for e.g. use CDN on S3, or another not "standart" way. {{STATIC_URL}} is equivalent to {% static %} in other cases.

You also get new storage.CachedStaticFilesStorage, that can add md5-hash to filenames from static, to make cash for css, js, images and so on definitely invalid.

|truncatechars filter

Incredible but true. After 4,5 years of Django dev you received |truncatechars in default filers list. It can trim string to provided amount of characters and  change the end of it into three dots... Anyway |truncate_words is also available.

Almost all "IMHO tasty new features in 1.4 templates" covered. The farther the more will come. Stay tuned.