Django templates: overriding blocks of included children templates through an extended template

Question

I’m wondering if anyone knows how to deal with the following quirky template structure:

### base.html
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html lang="en">

<head>
  <title> {% block title %} Title of the page {% endblock %} </title>
</head>

<body>
  <header>
    {% block header %}
      {% include "base/header.html" %}
    {% endblock header %}
  </header>
  {% block content %}{% endblock %}
</body>

</html>

### base/header.html
<div id="menu-bar">
  {% block nav %}
    {% include "base/nav.html" %}
  {% endblock %}
</div>

### base/nav.html
<nav id="menu">
  <ul>
    <li>
      <a href="/profile/">My Profile</a>
    </li>
    <li>
      <a href="/favs/">My Favorites</a>
    </li>
    {% block extra-content %}{% endblock %}
  </ul>
</nav>

And, the heart of the matter:

### app/somepage.html
{% extends "base.html" %}
{% block content %}
  <p>Content is overridden!</p>
{% endblock %}

{% block extra-content %}
  <p>This will not show up, though...</p>
{% endblock %}

{% block nav %}
  <p>Not even this.</p>
{% endblock %}

The problem is when extending a template you can only override the blocks declared in the parent only, not any of its children.

I suppose I could make base.html a husk of empty unused nested blocks covering all future contingencies, but would even that override properly? And is that the only way?

If you’re wondering why I have a bi-directional include/extends workflow around base.html, I have many sub-templates that I want to get used all across the project: Headers, footers, navs, sidebars, etc. They all will be consistant in structure across the entire site, but in many cases a whole subdivision of the site will only need a few of those sub-templates. My idea was to define the sub-templates under the templates/base folder, and have templates/base-type1.html, templates/base-type2.html, etc to extend in other places. Each type would only reference the sub-templates needed, and override them to place content as needed.

Asked By: Chris Keele

||

Source

Answer 1

You can solve this by extending your currently-included templates, then including the extension instead of the the currently-included base template.

Answered By: Marcin

Answer 2

It seems to be little known that you can use the with keyword with the include to pass variables into the context of an included template – you can use it to specify includes in the included template:

# base.html
<html>
    <body>
        {% block header %}{% include "header.html" %}{% endblock %}
    </body>
</html>

# header.html
# some stuff here
<div id="header">
    <img src="logo.png">
    {% include nav_tmpl|default:"navigation.html" %}
</div>

# special_page.html (uses other navigation)
{% extends "base.html" %}
{% block header %}
    {% include "header.html" with nav_tmpl="special_nav.html" %}
    # you might also want to wrap the include in an 'if' tag if you don't want anything
    # included here per default 
{% endblock %}

This approach saves you at least from having one additional file just for the purpose of overwriting a block. You can also use the with keyword to pass a value through a bigger hierarchy of includes as well.

Answered By: Bernhard Vallant

Answer 3

A terser variant to the solution proposed by @Bernhard Vallant:

# base.html
<html>
    <body>
        {% block header %}{% include "header.html" %}{% endblock %}
    </body>
</html>

# header.html
# some stuff here
<div id="header">
    <img src="logo.png">
    {% include nav_tmpl|default:"navigation.html" %}
</div>

# special_page.html (uses other navigation)
{% extends "base.html" %}
{% block header %}
    {% with nav_tmpl="special_nav.html" %}
        {{ block.super }}
    {% endwith %}
{% endblock %}

Answered By: Julián Landerreche

Django templates: overriding blocks of included children templates through an extended template

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