django-templatecomponents

Author:	Filip Noetzel
Version:	v0.03
Web:	http://j03.de/projects/django-templatecomponents/
Git:	git clone http://j03.de/git/django-templatecomponents.git/ ( browse, also on github)
Download:	django-templatecomponents.tar.gz

A django application that makes it easy to organize your component source (JavaScript, CSS) in your django templates.

Overview

Define your JavaScript and CSS source right beneath the HTML skeleton that it's used on:

template.html:

{% css print %}
  a[href]:after{
    content: " [" attr(href) "] ";
  }
{% endcss %}

{% css screen print %}
  #clickme { font-weight: bold; }
{% endcss %}

{% js client %}
  document.getElementById('clickme').onclick = function() {
    alert('Ugh! I have been clicked');
  }
{% endjs %}

<a id='clickme' href="/click/">Click me</a>

This would result in

print.css:

/* extracted css from template '/path/to/template.html' with groups print */
a[href]:after{
  content: " [" attr(href) "] ";
}
/* extracted css from template '/path/to/template.html' with groups print screen */
#clickme { font-weight: bold; }

screen.css:

/* extracted css from template '/path/to/template.html' with groups print screen */
#clickme { font-weight: bold; }

client.js:

/* extracted css from template '/path/to/template.html' with groups client */
document.getElementById('clickme').onclick = function() {
  alert('Ugh! I have been clicked');
}

Benefits

Serve your components from one file

(see also rule #1)

You can arrange your template component blocks in (multiple) groups, to access them by different urls (Here, print.js will contain the concatenated content of the first two blocks).

One can imagine groups for

• printing CSS
• screen CSS
• presentation CSS
• additional CSS and JavaScript for authenticated / paying users
• CSS for browers with enabled or disabled JavaScript
• CSS and JavaScript for mobile devices
• CSS and JavaScript for legacy browsers
• Splitting the initial payload
• Splitting JavaScript in 25K-Slices for the iPhone

Usage

Static file generation

While you want your template components be processed on the fly while developing, you can generate static files from your template components upon each deployment:

$ ./manage.py generate_templatecomponents
Generating print.css
Generating screen.css
Generating screen.js

Priority based block dependency

Some CSS Rules and JavaScript might depend on each other (Specific CSS rules override basic CSS Rules; some of your JavaScript depends on your favorite ajax library).

Each block can have a priority, the following example illustrates this:

template1.html:

{% js xlib 5 %} x = x + 1; {% endjs %}

template2.html:

{% js xlib 10 %} var x = 1; {% endjs %}

This would ensure, the javascript block from template2.html appears above the one from template1.html:

xlib.js:

/* extracted javascript from '/path/to/template2.html' with priority 10 with groups screen*/
var x = 1;

/* extracted javascript from '/path/to/template1.html' with priority 5 with groups screen*/
x = x + 1;

It is recommended to give a high priority for JavaScript libraries, a lower for custom built library code and a very low priority for custom code snippets.

Including external libraries

You can easily include additional static files (like JavaScript libraries, CSS frameworks, ..), by specifying them in your settings.py:

TEMPLATECOMPONENTS_ADDITIONAL = {
    os.path.join(MEDIA_ROOT, 'js/prototype.js'):     'js 10 script',
    os.path.join(MEDIA_ROOT, 'js/scriptaculous.js'): 'js 9 script',
    os.path.join(MEDIA_ROOT, 'js/effects.js'):       'js 8 script',
    # ..
}

This way, you can avoid putting third party code in your templates/ directory and adding django template tags in the first and last line.

Preprocessing JavaScript and CSS with Django Templates

You can use every aspect of the django template language and all the builtin template tags and filters.

However, the context that is available within the templatecomponent-tags only contains settings (with the contents of your settings.py).

Note

The {% css %} and {% js %} blocks are evaluated once at deployment time, when you generate the static files.

Examples

Settings-dependent inclusions

{% js script %}
  var pageTracker = _gat._getTracker("{{ settings.GOOGLE_ANALYTICS_KEY }}");
  pageTracker._trackPageview();
{% js %}

Debug-build

{% js script %}
  var complex = function() {
    {% if settings.debug %}
      console.log("Complex function invoked");
    {% endif%}
    var x = 5;
    // very complex code..
  }
{% js %}

CSS Variables

{% css style %}
  body {
    background-color: {{ settings.colors.background }};
  }
{% endcss %}

Installation

Download

Using git:

git clone http://j03.de/git/django-templatecomponents.git/

Using tarball:

curl 'http://j03.de/git/?p=django-templatecomponents.git;a=snapshot;sf=tgz' > django-hashedmedia.tar.gz
tar -xvzf django-templatecomponents.tar.gz
rm django-templatecomponents.tar.gz

Put the folder django-templatecomponents somewhere in your $PYTHONPATH (presumably your project folder, where your manage.py lives).

Configuration

Adopt your development urls.py like this:

if settings.DEBUG:
    urlpatterns += patterns('',
        (r'^static/(?P<path>.*\.(js|css))$', 'templatecomponents.views.generate'),

        # make sure to have the above rule before your
        # django.views.static.serve rule

        (r'^static/(?P<path>.*)$', 'django.views.static.serve', {
          'document_root': settings.MEDIA_ROOT
        }),
    )

Misc

Syntax highlighting in vim

To get the syntax highlighting for the (now embedded) css and javascript in vim, create a file at ~/.vim/after/syntax/htmldjango.vim with the following contents:

syn region javaScript start=+{% js+ keepend end=+{% endjs %}+me=s-1 contains=@htmlJavaScript,htmlCssStyleComment,htmlScriptTag,@htmlPreproc
syn region cssStyle start=+{% css+ keepend end=+{% endcss %}+ contains=@htmlCss,htmlTag,htmlEndTag,htmlCssStyleComment,@htmlPreproc

What next ?

• Convert all your components to template components.
• Read Steve Souder's "High Performance Web Sites"
• See django-hashedmedia to speed up your loading times even further.

License

django-templatecomponents is licensed as Beerware, patches (including documentation!) and suggestions are welcome.