A high level overview of Twig and its functions that was presented at the OC Drupal meetup in February 2014 at KWALL.
As Twig is now part of Drupal 8 core, it is still being developed so slides are mostly on Twig itself. Discussion was over what Twig provides to themers.
http://www.meetup.com/oc-php
http://www.meetup.com/ocdrupal/
2. ME
•
PHP Application Developer
Who happens to do Drupal
Who also likes to dabble in frontend
•
Experience with Twig is in Silex, a micro-framework
built on Symfony
•
Been organizer of OCPHP for nearly 8 years and OC
Drupal around ~4 years
4. WHAT IS TWIG
•
A PHP Template Engine to separate Presentation
Layer from the Controller/Model (PHP)
•
Developed by same people behind Symfony; yes,
that’s in Drupal 8 Core too
6. BUT PHP WAS JUST FINE,
WHY TWIG ?
•
Mixed PHP with HTML can be just plain sloppy and hard to read
•
PHP still has to scan html documents looking for all those <?php
tags amongst the HTML
•
Designers have too much power and can open security bugs in
the presentation layer with PHP
•
Defining a function or filtering for theming was sloppy — no real
standard way
7. I DON’T WANT MORE BLOAT
•
PHP is definitely faster but Twig is safer
As a developer, you control the PHP executed in a template. No possible
coding hacks like this in Templates …
•
<?php $user = db_query(“SELECT n.nid FROM users WHERE uid = “.
$_GET[‘uid’].“)”; ?>
•
Obviously a bit more execution time and memory but Twig has been around for
a while, tested, and aims to be fast ! Generated PHP will run through OPCode.
•
Twig caches the generate PHP code so only changes are re-generated
8. Besides … In Drupal, Twig is the least of your
worries when it comes to bloat.
Rendered Arrays
10. BENEFITS
•
An extendable template engine
•
Secure (can enable variable output escaping globally)
•
It’s Unit Tested
•
Great documentation and online resources
•
Not coupled to Symfony so it has its own roadmap and
community
11. EVEN MORE BENEFITS
•
Easy to understand clean syntax
•
Extend it and create your own filters or functions to give
designers to use
•
Once you know it, can use it in other PHP frameworks outside of
Drupal
•
Syntax support in several IDEs (PHPStorm)
http://blog.jetbrains.com/phpstorm/2013/06/twig-support-inphpstorm/
18. IF
<?php if (isset($user[‘name’])) { echo $user[‘name’] } else { echo
‘Who are you?’ }; ?>
!
{% if user.name is defined %}
{{ user.name }}
{% else %}
Who are you?
{% endif %}
!
Not testing, but following might work too
{% user.name|default(‘Who are you’) %}
19. LOOPS
<?php foreach ( $users as $key => $user ) { print
$user[‘name’]; } ?>
!
{% for key, user in users %}
{{ user.name }}
{% endfor %}
20. CONTROL WHITESPACE
use - in output or function tags
!
{{- user.name -}}
!
{%- if user.name is defined -%}{%- endif -%}
!
22. CONCAT / SET STRINGS
<?php print strtolower(‘’Greeting ‘ . $user[‘first’]); ?>
!
{% set greeting = 'Hello ' %}
{% set name = user.first %}
!
{{ greeting ~ name|lower }} {# Hello bob #}
!
{{ (greeting ~ name)|lower }} {# hello bob #}
23. EXPRESSIONS
{% if 1 not in [1, 2, 3] %}
!
{% if 'cd' in 'abcde' %}
!
{% if 'Bob' starts with 'B' %}
!
{% if phone matches '{^[d.]+$}' %}
!
http://twig.sensiolabs.org/doc/templates.html#twig-expressions
24. LOGIC WITH EXPRESSIONS
PHP: && || <>
!
and
or
not
!
{% if user.name is not defined or user.name == ‘Bob’ %}
!
http://twig.sensiolabs.org/doc/templates.html#twig-expressions
25. EXTENDING
Don’t duplicate the whole twig file just to change a single piece of
output. Extend it.
!
{% extends ‘layout.html.twig’ %}
!
or if layout = “layout.html.twig” was set as Twig Global/var
!
{% extends layout %}
26. CONDITIONAL EXTENDS
(mobile variable is set in code and passed to template)
!
{% extends mobile ? “mobile.html.twig" : “layout.html.twig” %}
!
!
!
27. BLOCKS
Define content in blocks to allow for extending of templates !
!
{% block sidebar %}
…content…
{% endblock %}
!
!
28. OVERRIDING BLOCKS
The benefit of extending and defining blocks in a template.
!
Any child template can override just that block content from
the parent template without having to change any other html !
!
29. OVERRIDING BLOCKS
{% extends '/core/modules/system/tests/modules/twig_theme_test/
modules/twig_namespace_a/templates/test.html.twig' %}
!
{% block content %}
I just overrode the content block in the parent template.
{% endblock %}
!
!
30. INCLUDE OTHER TEMPLATES
{% extends ‘layout.html.twig’ %}
!
{% include ‘sidebar-left.html.twig’ %}
!
{% block content %}
I just overrode the content block in the parent template.
{% endblock %}
!
!
!
33. DEBUG IN DRUPAL 8
!
{{ dump(user) }}
!
!
!
Since Twig process the template into a generate PHP file, don’t
believe you can step through with XDebug and IDE like PHPStorm.
(??)
34. TWIG LOOKS GREAT !
BUT NOW WHAT ?
!
It’s a huge undertaking to replace the theme layer and currently
still progressing but several templates have been converted:
views, base templates, etc.
!
Twig Initiative ToDo List
!
https://groups.drupal.org/node/278968
35. D7 TO D8 TEMPLATES
Extensive work required but checkout Twigify
!
Twigify is a module for converting Drupal 7 PHP Template
themes to Drupal 8 Twig themes. It was presented/demoed at
Drupalcon Portland (BOF) and at numerous US camp sessions,
and also in the Twig Lab at Drupalcon Prague.
!
https://drupal.org/node/2099611
!
