django: using blocks in included templates

Django does not process blocks in included files.

The include tag should be considered as an implementation of "render this subtemplate and include the HTML", not as "parse this subtemplate and include its contents as if it were part of the parent". This means that there is no shared state between included templates -- each include is a completely independent rendering process. (Django template tag documentation)

I came across this problem and ended up with the following compromise, hoping someone else might find it useful. It relies on using with blocks in the child templates.

base.html wants to reuse a common nav.html include, but define some blocks where variables inside nav.html might be overriden by child templates.

<!-- base.html: -->
<html>
  [...]
  <nav class="desktop">
    {% block desktop_nav %}
      {% include "includes/nav.html" %}
    {% endblock %}
  </nav>
  [...]
  <nav class="mobile">
    {% block mobile_nav %}
      {% include "includes/nav.html" %}
    {% endblock %}
  </nav>
  [...]

The include template depends on a variable called selected, which base.html does not define, by default:

<!--includes/nav.html:-->
<a href="/about/" class="{% if selected == 'about' %}selected{% endif %}">About</a>
<a href="/people/" class="{% if selected == 'people' %}selected{% endif %}">People</a>
<a href="/contact/" class="{% if selected == 'contact' %}selected{% endif %}">Contact</a>

But child pages can override that value as follows:

<!--about.html:-->
{% extends "base.html" %}
{% block desktop_nav %}{% with selected='about' %}{{ block.super }}{% endwith %}{% endblock %}
{% block mobile_nav %}{% with selected='about' %}{{ block.super }}{% endwith %}{% endblock %}

so, not perfect, I still have to have two separate blocks and use those with blocks twice, but it does allow me to override variables in include blocks from the parent template.

It seems that the final template is trying to extend itself (if it was in quotes).

You really don't need that much of complexity. It's actually pretty much simpler.

The base template should hold the skeleton of your template, then you can extend it to make customizations. For reusable code blocks that you don't want to include in your every view, include them where appropriate but don't use any block, extends or include statement within the included file. Django will not parse those but the context variable passed from the view can still be used.

In short, you can create variables in whichever template you're planning to include e.g.

{{ localcontent }}

and then assign those variables wherever you include the template e.g.

{% include "name_snippet.html" with localcontent="Actual content" %}

django: using blocks in included templates

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