Without inheritance, every HTML template would contain duplicated code: navigation, CSS/JS links, footer. Inheritance lets you write a page skeleton once and extend it in child templates.
How It Works
base.html— a skeleton with placeholder blocks ({% block %})- A child template declares
{% extends 'base.html' %}and fills in the blocks
When rendering, Django takes the child template, finds the parent, and inserts the block contents.
base.html for DevBlog
{# templates/base.html #}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>{% block title %}DevBlog{% endblock %}</title>
{% load static %}
<link rel="stylesheet"
href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0/dist/css/bootstrap.min.css">
<link rel="stylesheet" href="{% static 'css/main.css' %}">
{% block extra_css %}{% endblock %}
</head>
<body>
<!-- Navigation -->
<nav class="navbar navbar-expand-lg bg-dark navbar-dark">
<div class="container">
<a class="navbar-brand" href="{% url 'post-list' %}">DevBlog</a>
<button class="navbar-toggler" type="button"
data-bs-toggle="collapse" data-bs-target="#navMenu">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navMenu">
<ul class="navbar-nav ms-auto">
<li class="nav-item">
<a class="nav-link" href="{% url 'post-list' %}">Articles</a>
</li>
<li class="nav-item">
<a class="nav-link" href="{% url 'about' %}">About</a>
</li>
</ul>
</div>
</div>
</nav>
<!-- Django flash messages -->
{% if messages %}
<div class="container mt-3">
{% for message in messages %}
<div class="alert alert-{{ message.tags }} alert-dismissible fade show">
{{ message }}
<button type="button" class="btn-close" data-bs-dismiss="alert"></button>
</div>
{% endfor %}
</div>
{% endif %}
<!-- Main content -->
<main class="container py-4">
{% block content %}{% endblock %}
</main>
<!-- Footer -->
<footer class="bg-dark text-light py-4 mt-5">
<div class="container text-center">
<p class="mb-0">© {{ now.year }} DevBlog. Built with Django.</p>
</div>
</footer>
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0/dist/js/bootstrap.bundle.min.js"></script>
{% block extra_js %}{% endblock %}
</body>
</html>
Blocks in base.html:
| Block | Purpose |
|---|---|
{% block title %} |
Browser tab title |
{% block extra_css %} |
Additional CSS for a specific page |
{% block content %} |
Main page content |
{% block extra_js %} |
JS for a specific page |
Child Template: Article List
{# templates/blog/post_list.html #}
{% extends 'base.html' %}
{% block title %}Articles — DevBlog{% endblock %}
{% block content %}
<h1>All Articles</h1>
<div class="row g-4">
{% for post in posts %}
<div class="col-12 col-md-6 col-lg-4">
<div class="card h-100">
<div class="card-body">
<h5 class="card-title">
<a href="{% url 'post-detail' slug=post.slug %}">{{ post.title }}</a>
</h5>
<p class="card-text text-muted">{{ post.summary }}</p>
</div>
</div>
</div>
{% endfor %}
</div>
{% endblock %}
Child Template: Article Page
{# templates/blog/post_detail.html #}
{% extends 'base.html' %}
{% load static %}
{% block title %}{{ post.title }} — DevBlog{% endblock %}
{% block extra_css %}
<link rel="stylesheet" href="{% static 'css/highlight.css' %}">
{% endblock %}
{% block content %}
<article>
<h1>{{ post.title }}</h1>
<p class="text-muted">{{ post.published_at|date:"F j, Y" }}</p>
<div class="post-body">
{{ post.body|safe }}
</div>
</article>
{% endblock %}
{% block extra_js %}
<script src="{% static 'js/highlight.js' %}"></script>
{% endblock %}
{{ block.super }} — Extending a Block
{{ block.super }} inserts the parent block’s content without replacing it:
{# In a child template: #}
{% block title %}{{ post.title }} — {{ block.super }}{% endblock %}
{# Result: «Introduction to Python — DevBlog» #}
Useful for blocks containing navigation or scripts when you want to add to the existing content rather than replace it.
Inheritance Chains
You can build chains: base.html → base_blog.html → post_detail.html. More than two or three levels makes the code hard to follow — keep it reasonable.
base.html
└── blog/base_blog.html (adds a sidebar)
├── post_list.html
└── post_detail.html
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