drupal 8: frontend development
TRANSCRIPT
And… what do you want?
○ What’s new in Drupal 8 themes;
○ Where is…?
○ How to…?
○ Let’s try!
○ Twig: the new template engine;
○ Playing with Twig
What’s new in Drupal 8 for themers
D7○ PHPTemplate
○ Theme functions + template files
○ Structured markup in core and ‘hardcoded’ classes
○ HTML
D8○ Twig
○ Template files
○ Minimal markup and classes in core
○ HTML5 in core
Theme folder structure
The directory structure of Drupal 8 has changed!
https://www.drupal.org/node/2349803
“sites/all/themes…”MISSING!!
Most common theme files
*.info.yml
*.libraries.yml
*.breakpoints.yml
*.theme
Theme folder structure: https://www.drupal.org/node/2349803
*.info.yml (ex *.info)
○ A theme must contain an .info.yml file to define the theme.
○ Among other things the .info.yml file defines general informations, style sheets, and block regions.
○ This is the only required file in the theme.
*.libraries.yml
○ The .libraries.yml file is used to define JavaScript and CSS libraries that can be loaded or not by the theme.
○ Used also to override CSS or JS.
○ A library as a collection of CSS and JS.
https://www.drupal.org/docs/8/theming-drupal-8/adding-stylesheets-css-and-javascript-js-to-a-drupal-8-themehttps://ffwagency.com/digital-strategies-blog/managing-css-and-javascript-files-drupal-8-libraries
*.libraries.yml: drink responsibly!
Be careful:
“global-styling” or “global-js” is not the only way to add assets!
It’s possible to create different libraries (with CSS and JS) and use them separately!
https://www.drupal.org/docs/8/theming-drupal-8/adding-stylesheets-css-and-javascript-js-to-a-drupal-8-themehttps://www.drupal.org/docs/8/creating-custom-modules/adding-stylesheets-css-and-javascript-js-to-a-drupal-8-moduleTo see some parameters for single asset: http://www.bradwade.com/drupal8/D8-3-Libraries/
*.breakpoints.yml
○ Breakpoints define where a responsive design needs to change in order to respond to different devices.
○ Breakpoints are defined in a .breakpoints.yml file
HEY! Responsive image module in core!
*.theme (ex template.php)
○ The .theme file is a PHP file that contains all the conditional logic and data (pre)processing of the output.
Bye bye theming functions!
ALL GONE: All of the theme() functions have been converted to Twig templates.
New theme hooks
○ Theme suggestions
hook_theme_suggestions()hook_theme_suggestions_HOOK()
○ Theme suggestions alter: hook_theme_suggestions_alter(), hook_theme_suggestions_HOOK_alter()
○ Theme preprocess:
THEME_preprocess(array &$variables, $hook), THEME_preprocess_HOOK(array &$variables)
The preprocess layer
○ The preprocess layer still exists, but it's used for a different purpose.
○ In Drupal 8, the preprocess layer should not be used to add css classes.
The preprocess layer #2
○ This should be done in the template files.
https://www.drupal.org/node/2325067
Drupal 8 core themes
○ bartik○ seven○ stark
○ classy○ stable
Backwards compatibility throughout the Drupal 8 cycle
Default admin theme
Default theme
Drupal core markup test theme
Drupal 8 core themes: bartik
A flexible, recolorable theme with many regions and a responsive, mobile-first layout.The default theme in Drupal 8.
Drupal 8 core themes: stark
An intentionally plain theme with almost no styling to demonstrate default Drupal’s HTML and CSS.
Stark only outputs html and css from modules.
○ Add no CSS○ Add no templates
Drupal 8 core themes: stable
The Stable theme will function as a backwards compatibility layer for Drupal 8's core markup, CSS and JS. A theme will always use Stable as the base theme unless you use another base theme or set
in your theme .info.yml file.
Drupal 8 core themes: classy
The classes from core have been moved into the classy base theme. Now all template files in core are “classless”.
Is the base theme that Seven and Bartik will extend from.
Classy vs Stable
https://www.lullabot.com/articles/a-tale-of-two-base-themes-in-drupal-8-core
New CSS architecture
SMACSSScalable and Modular Architecture for CSS
• Base• Layout• Component• State• Theme
BEMBlock Element Modifier naming convention
.block__element--modifier
Development tools
Before start with theme development (Drupal development) let’s get some tools:
Drush: http://www.drush.org Drupal Console: http://drupalconsole.com Devel module (& Kint): http://drupal.org/project/devel
Most useful drush commands:
○ Clear cachedrush cr
○ Download / enable a moduledrush en module_name
○ Uninstall a moduledrush pm-uninstall module_name
○ HELP ME! drush help
Most useful console commands:
○ Generate a theme:drupal generate:theme
○ Generate a module:drupal generate:module
○ Generate a block:drupal generate:plugin:block
○ List drupal routes:drupal router:debug
https://hechoendrupal.gitbooks.io/drupal-console/content/en/index.html
Enable debugging:the manual way
○ Locate services.yml file (sites/default/services.yml)○ If services.yml does not yet exist copy
default.services.yml and rename it to services.yml○ Edit the services.yml file and enable one or more of the
debugging options○ Rebuild cache
Enable debugging:the manual way (continue)
parameters:
twig.config:
# Twig debugging:
debug: true
# Twig auto-reload:
auto_reload: true
# Twig cache:
cache: false
services.yml
Enable debugging: Drupal Console
https://www.drupal.org/node/1903374
drupal site:mode dev
Disable render cache
Drupal caches any rendering it performs for blocks and entities, to speed up subsequent page loads.
This means that changes to Twig templates for these will not take effect immediately.
Disable render cache
○ add the following lines at the bottom of settings.phpif (file_exists($app_root . '/' . $site_path . /settings.local.php')) {
include $app_root . '/' . $site_path . /settings.local.php';
}
○ copy sites/example.settings.local.php to sites/default/settings.local.php
○ clear the Drupal caches.
Disable render cache
In settings.local.php:
○ disable the render cache (this includes the page cache).$settings['cache']['bins']['render'] = 'cache.backend.null';
○ disable Dynamic Page Cache.$settings['cache']['bins']['dynamic_page_cache'] = 'cache.backend.null';
Let’s try!
○ Create new theme with drupal console;
○ Theme debug on;
○ Add CSS with libraries file;
○ Disable classy libraries;
Twig: what & why
What?
○ A template engine for PHP
Why?
○ Twig was created by people behind Symfony2
○ Drupal 8 uses some components of Symfony2
Twig was chosen because it was the best choice after comparing various templating languages.
"… We don't have Twig because we have Symfony. It's more that, we have Twig because it's AWESOME"
- Scott Reeves, @Cottser
“Twig…because it's AWESOME”
#2. D8: less complexity
D8 is boring!
https://sqndr.github.io/d8-theming-guide/new-theming-layer/index.html
#3. D7: redundancy
There's a lot of duplicated code in themes, we often have multiple files with the same lines of code.
#3. D8: less redundancy
No need to repeat code between templates, we can extend templates with Twig.
#4. Security
D7In a PHPTemplate file you can print all sort of unsanitized data, even delete a table from your DB.
D8In Twig this is not possible, Twig's autoescape feature is enabled by default.
Twig: |Functions (filters custom)
Twig can be extended in many ways; you can add extra tags, filters, tests, operators, global variables, and
functions.
http://twig.sensiolabs.org/doc/2.x/advanced.htmlhttp://symfony.com/doc/current/templating/twig_extension.htmlhttp://web4pro.net/blog-news/custom-twig-filter/http://leopathu.com/content/create-custom-twig-filter-drupal-8
Twig coding standard (T.c.s.)
○ Generic Twig coding standards: http://twig.sensiolabs.org/doc/coding_standards.html
○ Twig in Drupal coding standards: http://drupal.org/node/1823416
T.c.s. - HTML attributes
In Drupal core, we will print only the class attribute specially, all the others will be printed as part of {{ attributes }}.
The reason for this is that it needs to be very easy for front end developers to be able to add a class, anywhere
block.html.twig
T.c.s. - Whitespaces
Use the spaceless tag to remove whitespace between HTML tags, not whitespace within HTML tags or whitespace in plain text.
Say me more...
https://www.drupal.org/project/twig_field_value
Filters:- field_label : Returns the field label value.- field_value : Returns the render array of the field value(s) without the
field wrappers.- field_raw: Returns raw field properties value(s).- field_target_entity: Returns the referenced entity object(s) of an
entity reference field.
And so, Twig advantages:
○ a clear separation between the logic and the view
○ no more PHP code inside your template files○ it's not only used in Drupal core, so it's not a
Drupaly-thing
Let’s try twig so!
○ Override a template;
○ Extend a template;
○ hook_suggestions_hook_alter;
○ Work in a exemple template file.
Resources
○ Twig official: http://twig.sensiolabs.org/
○ Theming Drupal 8: https://drupal.org/theme-guide/8
○ The Drupal 8 Theming guide: http://d8.sqndr.com/
More articles
○ Drupal 8 Theming Fundamentals, Part 1
○ Drupal 8 Theming Fundamentals, Part 2
○ A Tale of Two Base Themes in Drupal 8 core