Guides > Theming Cheat Sheet


Did you get a Theming Cheat Sheet? Our printed Cheat Sheet contains an example Twig template, steps to overriding a template and inspecting variables, and interpreting Twig debug output. This guide contains the text of our Cheat Sheet along with related tutorials for a quick reference. New to Drupal 8 Theming? Start with our Hands-On Theming guide, based on our popular Drupal 8 Theming Workshop. Our Theme Drupal Sites guide contains a more extensive curriculum.

What will you learn

  • Find tutorials related to our Cheat Sheet
  • Twig
  • Templates
  • Overriding templates
  • Twig debugging
  • Inspecting variables

What about Drupal 9?

Long story, short: the vast majority of Drupal 8 tutorials will work on Drupal 9 sites. Due to how innovation now works in Drupal, new features are released in minor versions. Major releases, like the release of Drupal 9, contain all the features of Drupal 8, but with deprecated APIs removed, and some 3rd-party libraries updated. Learn more about Drupal 9 and what it means for your learning journey in our Guide to Drupal 9.

Cheat Sheet

Override a Template and Discover Variables

1. Turn on Twig debugging.

2. View source. Which template is being used?

Look for BEGIN OUTPUT from.

3. Copy the file into your theme's templates directory. Optional: Rename file to change its scope using File Name Suggestions.

4. Clear the cache (Configuration > Performance > Clear all caches or drush cr)

5. Inspect variables.

Use {{ dump(_context|keys) }} in template to see which variables are available.

Example Twig Debug Output (View Source)

After turning on Twig debug mode, view source on any page of your Drupal site to see the Twig debug output in HTML comments.

<!-- THEME DEBUG -->
<!-- THEME HOOK: 'page'
  * page--node--1.html.twig
  * page--node--%.html.twig
  * page--node.html.twig
  x page.html.twig
<!-- BEGIN OUTPUT from 'themes/icecream/templates/page.html.twig' -->

Twig Template Example

Learn about template variables in comment blocks

{# Learn about template variables in comment blocks
  - items: A list of ice cream flavors
    - title: Link title
  - author: Author of content

Discover variables with dump().

{# Discover variables with dump(). #}
  {{ dump(_context|keys) }}

Attach an asset library in a template

{# Attach an asset library in a template. #}
  {{ attach_library('classy/node') }}

Define a variable

{# Define a variable. #}
{% set date = node.created|format_date('long') %}

Add a CSS class

<article{{ attributes.addClass('about') }}>

Make hard-coded text translatable

  {# Translatable text with vars, use trans. #}
  <p class="byline">{% trans %}by {{ author }} on {{ date }}{% endtrans %}</p>

  {# Translatable text without variables, use t. #}
  <h3>{{ 'Ice Cream Flavors'|t }}</h3>

Iterate over a list with a for loop

  {# Iterate over a list with a for loop. #}
  <ul class="ice-cream-list">
  {% for item in items %}
    <li class="ice-cream-list--flavor">{{ item.title }}</li>
  {% endfor %}

Create a link in a template

  {# Links in templates. If you know the route: #}
   <a href="{{ url('contact.site_page') }}">{{ 'Contact'|t }}</a>

  {# If you don't know the route: #}
  {{ link('Contact'|t, 'base:about/contact', { 'class':[] }) }}


Related tutorials

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