Hi All,
I would like to propose a new template tag to be included in Django, it is
sort of a cross between 'include' and 'extends'. You can find an
implementation here: https://gist.github.com/samwillis/af3992f69c2597a16252
The main use case for this tag is being able to create reusable
'components' for rendering a website. Say for example a page header, a
panel with headers and footers, or a modal window (as seen in the Bootstrap
framework). Rather than needing to repeat the html everywhere you need it
and having to search out all occurrences to make a change to the structure
you can create a simple template and include it.
To some extent this can currently be done with either an included template
using the '{% include "template.html" with var="value" %}' syntax or using
a custom template tag. However, the former isn't suitable for changing
whole blocks in the include template, and the latter can be overkill and
may not be suitable for a designer with little knowledge of Python and the
Django Template API.
The 'use' tag loads a template and renders it with the current context
similar to the 'include' tag. You can pass additional context using keyword
arguments as well as override blocks in the included template.
Example (simple) template:
<div class="page-heading {{ extra_class }}">
<h1>{% block heading %}{% endblock %}</h1>
</div>
Example 'use' tag use with the above template:
{% use "page_header.html" %}
{% block heading %}Some Title{% endblock %}
{% enduse %}
{% use "page_header.html" with extra_class="large" %}
{% block heading %}Some Title{% endblock %}
{% enduse %}
As with 'include' use the 'only' argument to exclude the current context
when rendering the included template:
{% use "page_header.html" only %}
{% block heading %}Some Title{% endblock %}
{% enduse %}
{% use "page_header.html" with extra_class="large" only %}
{% block heading %}Some Title{% endblock %}
{% enduse %}
The included template receives an additional context variable called
'used_blocks' which is a Dict indicating which blocks were overridden in
the 'use' tag. Using this you can conditionally show content around the
block. For example, if you had this template for generating a page heading:
<div class="page-heading">
<h1>{% block heading %}{% endblock %}</h1>
{% if used_blocks.sub_heading %}
<h2>{% block sub_heading %}{% endblock %}<h2>
{% endif %}
</div>
and included it using:
{% use "page_header.html" %}
{% block heading %}My Page Title{% endblock %}
{% enduse %}
it would exclude the '<h2>' tags from the empty subheading.
Finally, as syntactic sugar if you are just overriding a single block you
can express it as:
{% use "page_header.html" block heading %}
My Page Title
{% enduse %}
These example are a little simple, but this could be incredibly useful for
more complex components such a modal windows.
I have made a first pass at an implementation here:
https://gist.github.com/samwillis/af3992f69c2597a16252.
Although I have implemented this with the 'use' word, there may be a better
word. I considered 'embed' but thought 'use' was a little cleaner
Thanks,
Sam
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