Template inheritance

Using a base template

base.twig.html

<!DOCTYPE html>
<html>
    <head>
        <title>{{ title | default('Hello World') }}</title>
        <link rel="stylesheet" type="text/css" href="theme.css">
        {% block css %}
        {% endblock %}
    </head>
    <body>
    {% block body %}
        <nav>
        {% block navigation %}
            <a href="#">Link</a>
            <a href="#">Link</a>
            <a href="#">Link</a>
        {% endblock navigation %}
        </nav>
        <section id="container">
            <section id="content">
            {% block content %}
            <p>
            Lorem ipsum dolor sit amet.
            </p>
        </section>
        {% endblock content %}
    </section>
    {% endblock body %}
    </body>
</html>

page.twig.html

{% extends base.twig.html %}
{% block navigation %}
<a href="page2.html">Page 2</a>
<a href="page3.html">Page 3</a>
<a href="page4.html">Page 4</a>
{% endblock %}
{% block content %}
This is my first page
{% endblock content %}

Change the content of an included template

article.twig.html

<article>
    <h1>{{ article.title }}</h1>
    {% block content %}
    <p>{{ article.content }}</p>
    {% endblock %}
</article>

articles.twig.html

{# use default template for article #}
{% for article in articles %}
    {% include "article.twig.html" %}
{% endfor %}

{# use custom template for article #}
{% for article in articles %}
    {% embed "article.twig.html" %}
        {% block content %}
            <img src="{{ article.image }}" alt="{{ article.title }}" />
            {{ parent() }}
        {% endblock %}
    {% endembed %}
{% endfor %}

Variable inheritance

parent.html.twig

<!DOCTYPE html>
<html>
    <head>
        <title>{{ title_variable | default('Normal Page') }}</title>
    </head>
    <body>
         <h1>This is the {{ title_variable }} Page</h1>    
    </body>
</html>

child.html.twig

{% extends "parent.html.twig" %}
{% set title_variable = "Child" %}

Comparison of Include, Extends, Use, Macro, Embed

There are various types of inheritance and code reuse in Twig:

Include

The main goal is code reuse. Consider using header.html.twig & footer.html.twig inside base.html.twig as an example.

header.html.twig

<nav>
   <div>Homepage</div>
   <div>About</div>
</nav>

base.html.twig

{% include 'header.html.twig' %}
<main>{% block main %}{% endblock %}</main>

Extends

The main goal is vertical inheritance. Consider extending base.html.twig inside homepage.html.twig and about.html.twig as an example.

base.html.twig

{% include 'header.html.twig' %}
<main>{% block main %}{% endblock %}</main>

homepage.html.twig

{% extends 'base.html.twig' %}

{% block main %}
<p>You are at the homepage</p>
{% endblock %}

about.html.twig

{% extends 'base.html.twig' %}

{% block main %}
<p>You are at the about page</p>
{% endblock %}

Use

The main goal is horizontal reuse. Consider using sidebar.product.html.twig inside single.product.html.twig (extends product.layout.html.twig) and single.service.html.twig (extends ‘service.layout.html.page’) pages. (it’s like macros, but for blocks)

sidebar.html.twig

<aside>{% block sidebar %}{% endblock %}</aside>

single.product.html.twig

{% extends 'product.layout.html.twig' %}

{% use 'sidebar.html.twig' %}
{% block main %}
<p>You are at the product page for product number 123</p>
{% endblock %}

single.service.html.twig

{% extends 'service.layout.html.twig' %}

{% use 'sidebar.html.twig' %}
{% block main %}
<p>You are at the service page for service number 456</p>
{% endblock %}

Macro

The main goal is having reusable markup across many templates with variables. Consider a function which gets some variables and outputs some markup.

form.html.twig

{% macro input(name, value, type) %} <input type=”{{ type|default(‘text’) }}” name=”{{ name }}” value=”{{ value|e }}” }}” /> {% endmacro %}

profile.service.html.twig

{% import "forms.html.twig" as forms %}

<div>{{ forms.input('username') }}</div>

Embed

The main goal is block overriding. It has functionality of both Use & Include together. Consider embedding pagination.html.twig in product.table.html.twig & service.table.html.twig.

pagination.html.twig

<div>
    <div>{% block first %}{% endblock %}</div>
    {% for i in (min + 1)..(max - 1) %}
        <div>{{ i }}</div>
    {% endfor %}
    <div>{% block last %}{% endblock %}</div>
</div>

product.table.html.twig

{% set min, max = 1, products.itemPerPage %}

{% embed 'pagination.html.twig' %}
    {% block first %}First Product Page{% endblock %}
    {% block last %}Last Product Page{% endblock %}
{% endembed %}

service.table.html.twig

{% set min, max = 1, services.itemPerPage %}

{% embed 'pagination.html.twig' %}
    {% block first %}First Service Page{% endblock %}
    {% block last %}Last Service Page{% endblock %}
{% endembed %}

Please note that embedded file (pagination.html.twig here) has access to the current context (min, max variables here). Also you may pass extra variables to the embedded file:

pagination.html.twig

<p>{{ count }} items</p>
<div>
    <div>{% block first %}{% endblock %}</div>
    {% for i in (min + 1)..(max - 1) %}
        <div>{{ i }}</div>
    {% endfor %}
    <div>{% block last %}{% endblock %}</div>
</div>

product.table.html.twig

{% set min, max = 1, products|length %}

{% embed 'pagination.html.twig' with {'count': products|length } %}
    {% block first %}First Product Page{% endblock %}
    {% block last %}Last Product Page{% endblock %}
{% endembed %}