Scott Reeves

Joël Pittet

1:30 - 5:00

Now we can hit 'B' and gauge the personas in the audience. Ask people to raise their hand if they are:

• Site builders
• Themers
• Developers
• DevOps

Drupal 8 theme layer changes

Template process layer

…is gone!

5:00 - 8:00

• The main reason for the process layer was to flatten strings into HTML.
• In Drupal 8 we prefer "lazy" rendering things as late as possible, which usually gets called from the template.

Theme functions

…are being converted to Twig templates.

8:00 - 11:00

Theme suggestion hooks

Drupal 7:

<?php
/**
 * Implements hook_preprocess_HOOK() for node templates.
 */
function MYTHEME_preprocess_node(&$variables) {
  $variables['theme_hook_suggestions'][] = 'node__' . 'my_first_suggestion';
  $variables['theme_hook_suggestions'][] = 'node__' . 'my_second_more_specific_suggestion';
}
						

Drupal 8:

<?php
/**
 * Implements hook_theme_suggestions_HOOK_alter() for node templates.
 */
function MYTHEME_theme_suggestions_node_alter(array &$suggestions, array $variables) {
  $suggestions[] = 'node__' . 'my_first_suggestion';
  $suggestions[] = 'node__' . 'my_second_suggestion';
}
						

11:00 - 14:00

Goodbye theme(), hello render arrays

Drupal 7:

<?php
$variables['list'] = theme('item_list', array(
  'items' => $items,
));

Drupal 8:

<?php
$variables['list'] = array(
  '#theme' => 'item_list',
  '#items' => $items,
);

14:00 - 16:00

Instead of the list variable being a flat string of HTML, it's a render array that gets passed to the template and rendered from there.

Oh yeah, and Twig!

16:00 - 18:00

• Twig is a flexible, fast, and secure template engine for PHP.
• The Twig engine and initial integration code was committed during BADCamp in November 2012.
• The conversions of .tpl.php to .html.twig files were committed during DrupalCon Portland in May 2013 and Twig is now the default template engine for Drupal 8.

Sandwiches.

https://github.com/DrupalTwig/sandwich

20:00 - 21:00

We were hungry when we came up with this example.

Define using hook_theme()

<?php
/**
 * Implements hook_theme().
 */
function sandwich_theme() {
  return array(
    'sandwich' => array(
      'variables' => array(
        'attributes' => array(),
        'name' => '',
        'bread' => '',
        'cheese' => '',
        'veggies' => array(),
        'protein' => '',
        'condiments' => array(),
      ),
      'template' => 'sandwich',
    ),
  );
}
						

Build your render array

<?php
/**
 * Builds a sandwich.
 */
public function build() {
  return array(
    '#theme' => 'sandwich',
    '#name' => $this->t('Chickado'),
    '#attributes' => array(
      'id' => 'best-sandwich',
      'style' => 'float: left;',
      'class' => array('left', 'clearfix'),
    ),
    '#bread' => $this->t('Sourdough'),
    '#cheese' => $this->t('Gruyère'),
    '#veggies' => array($this->t('Avocado'), $this->t('Red onion'), $this->t('Romain')),
    '#protein' => $this->t('Chicken'),
    '#condiments' => array($this->t('Mayo'), $this->t('Dijon')),
  );
}
						

Pass in variables using #-prefixed keys.

- 24:00

Markup your Twig template

<section{{ attributes }}>
  <h2>{{ name }}</h2>
  {% if bread %}
    <p><strong>Bread:</strong> {{ bread }}</p>
  {% endif %}

  {% if protein %}
    <p><strong>Protein:</strong> {{ protein }}</p>
  {% endif %}

  {% if cheese %}
    <p><strong>Cheese:</strong> {{ cheese }}</p>
  {% endif %}

  {% if veggies %}
    <strong>Vegetables:</strong>
    <ul>
      {% for veg in veggies %}
        <li>{{ veg }}</li>
      {% endfor %}
    </ul>
  {% endif %}

  {% if condiments %}
    <strong>Condiments:</strong>
    <ul>
      {% for condiment in condiments %}
        <li>{{ condiment }}</li>
      {% endfor %}
    </ul>
  {% endif %}
</section>
						

Voilà!

That's the bare minimum for most practical use cases. But what if you need to do more, or if you're altering themeable output that someone else has defined? Let's dig a bit deeper.

Don't make a template for condiments. Real life example: toolbar.

Overview of rendering flow

28:00 - 33:00

drupal_render() is called on the render array. Any defined #pre_render callbacks are called. drupal_render() calls the now internal _theme() function.

After _theme() does its thing, #post_render callbacks can massage the resulting string.

Twig magic

{{ sandwich.cheese }}

// Array key.
$sandwich['cheese'];
// Object property.
$sandwich->cheese;
// Object method.
$sandwich->cheese();
// Object get method convention.
$sandwich->getCheese();
// Object is method convention.
$sandwich->isCheese();
// Object dynamic object property is set and get property.
$sandwich->__isset('cheese');
$sandwich->__get('cheese');

33:00 - 35:00

• checks if foo as an array and bar a valid element;
• if not, and if foo is an object, checks that bar is a valid property;
• if not, and if foo is an object, checks that bar is a valid method (even if bar is the constructor - uses __construct() instead);
• if not, and if foo is an object, checks that getBar is a valid method;
• if not, and if foo is an object, checks that isBar is a valid method;
• if not, returns a null value.