Drupal 8: The Crash Course

interface HttpKernelInterface {
  const MASTER_REQUEST = 1;
  const SUB_REQUEST = 2;

  /**
   * Handles a Request to convert it to a Response.
   *
   * @param Request $request A Request instance
   * @param integer $type    The type of the request
   * @param Boolean $catch Whether to catch exceptions or not
   *
   * @return Response A Response instance
   */
  public function handle(Request $request, $type = self::MASTER_REQUEST, $catch = true);
}

use Symfony\Component\HttpFoundation\Response;

class MyControllers {

  public function hello() {
    return new Response('<html><body>Hello World</body></html>');
  }
}

use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpFoundation\JsonResponse;

class MyControllers {

  public function hello() {
    return new Response('<html><body>Hello World</body></html>');
  }

  public function helloJson() {
    $data['Hello'] = 'World';
    return new JsonResponse($data);
  }
}

use Symfony\Component\HttpFoundation\StreamedResponse;

class MyControllers {

  public function helloCsv() {
    $lots_of_data = get_lots_of_data();

    $response = new StreamedResponse();
    $response->headers->set('Content-Type', 'text/csv');

    $response->setCallback(function() use ($lots_of_data) {
      foreach ($lots_of_data as $record) {
        print implode(', ', $record) . PHP_EOL;
      }
    });

    return $response;
  }
}

use Symfony\Component\HttpFoundation\BinaryFileResponse;

class MyControllers {

  public function privateFile() {
    return new BinaryFileResponse('secret_plans.odt');
  }
}

class MyControllers {

  public function helloDrupal() {
    return array(
      '#theme' => 'a_drupal_render_array',
      '#description' => 'Those still exist.',
    );
  }
}

/hello/world/{from}/{to}

use Symfony\Component\HttpFoundation\Request;

class HelloController {

  public function helloDrupal($to, $from, Request $request) {
    return array(
      '#theme' => 'love_letter',
      '#from' => $from,
      '#to' => $to,
    );
  }
}

module.routing.yml

hello.world:
  path: '/hello/world/{from}/{to}'
  defaults:
    _controller: '\Drupal\mymodule\Controller\HelloController::helloDrupal'
  requirements:
    _permission: 'access content'
    from: \s+
    to: \s+

/modules/hugs/hugs.info.yml

name: Hugs
description: Examples of hugs
type: module
core: 8.x

The modules page, showing the hug module.

/modules/hugs/src/Controller/HugsController.php

namespace Drupal\hugs\Controller;

use Drupal\Core\Controller\ControllerBase;

class HugsController extends ControllerBase {

  public function hug($to, $from) {
    $message = $this->t('%from sends hugs to %to', [
      '%from' => $from,
      '%to' => $to,
    ]);

    return ['#markup' => $message];
  }
}

/modules/hugs/hugs.routing.yml

hugs.hug:
  path: /hug/{from}/{to}
  defaults:
    _controller: 'Drupal\hugs\Controller\HugsController::hug'
    _title: 'Hug!'
  requirements:
    _permission: 'access content'

/modules/hugs/hugs.module

function hugs_theme() {
  $theme['hug_page'] = [
    'variables' => ['from' => NULL, 'to' => NULL],
    'template' => 'hug_page',
  ];

  return $theme;
}

/modules/hugs/template/hug_page.html.twig

<section>
  {% trans %}
    <strong>{{ from }}</strong> hugs <em>{{ to }}</em>
  {% endtrans %}
</section>

/modules/hugs/src/Controller/HugsController

namespace Drupal\hugs\Controller;

use Drupal\Core\Controller\ControllerBase;

class HugsController extends ControllerBase {

  public function hug($to, $from) {
    return [
      '#theme' => 'hug_page',
      '#from' => $from,
      '#to' => $to,
    ];
  }
}

/modules/hugs/config/install/hugs.settings.yml

default_count: 3

/modules/hugs/config/schema/hugs.settings.yml

hugs.settings:
  type: mapping
  label: 'Hug module settings'
  mapping:
    default_count:
      type: integer
      label: 'Default hug count'

/modules/hugs/src/Form/ConfigForm.php

namespace Drupal\hugs\Form;
use Drupal\Core\Form\ConfigFormBase;
use Drupal\Core\Form\FormStateInterface;

class ConfigForm extends ConfigFormBase {
  public function getFormId() { return 'hug_config'; }

  protected function getEditableConfigNames() {
    return ['hugs.settings'];
  }

  public function buildForm(array $form, FormStateInterface $form_state) {
    $config = $this->config('hugs.settings');

    $form['default_count'] = [
      '#type' => 'number',
      '#title' => $this->t('Default hug count'),
      '#default_value' => $config->get('default_count'),
    ];
    return parent::buildForm($form, $form_state);
  }

  public function submitForm(array &$form, FormStateInterface $form_state) {
    parent::submitForm($form, $form_state);
    $config = $this->config('hug.settings');
    $config->set('default_count', $form_state->getValue('default_count'));
    $config->save();
  }
}

/modules/hugs/hugs.routing.yml

hugs.config:
  path: /admin/config/system/hugs
  defaults:
    _form: 'Drupal\hugs\Form\ConfigForm'
    _title: 'Hug configuration'
  requirements:
    _permission: 'configure_hugs'

/modules/hugs/hugs.permissions.yml

configure_hugs:
  title: 'Configure the hugs system'
  description: 'Configure default hug count'

/modules/hugs/hugs.links.menu.yml

hugs.config:
  title: 'Hugs configuration'
  description: 'Configure the hugs system'
  route_name: hugs.config
  parent: system.admin_config_system

/modules/hugs/src/Controller/HugsController

namespace Drupal\hugs\Controller;

use Drupal\Core\Controller\ControllerBase;

class HugsController extends ControllerBase {

  public function hug($to, $from, $count) {
    if (!$count) {
      $count = $this->config('hugs.settings')->get('default_count');
    }
    return [
      '#theme' => 'hug_page',
      '#from' => $from,
      '#to' => $to,
      '#count' => $count
    ];
  }
}

/modules/hugs/hugs.routing.yml

hugs.hug:
  path: /hug/{from}/{to}/{count}
  defaults:
    _controller: 'Drupal\hugs\Controller\HugsController::hug'
    _title: 'Hug!'
    count: 0
  requirements:
    _permission: 'access content'
    count: \d+

/modules/hugs/hugs.module

function hugs_theme() {
  $theme['hug_page'] = [
    'variables' => ['from' => NULL, 'to' => NULL, 'count' => NULL],
    'template' => 'hug_page',
  ];

  return $theme;
}

/modules/hugs/template/hug_page.html.twig

<section>
  {% trans %}
    <strong>{{ from }}</strong> hugs <em>{{ to }}</em> {{ count }} time.
  {% plural count %}
    <strong>{{ from }}</strong> hugs <em>{{ to }}</em> {{ count }} times.
  {% endtrans %}
</section>

/modules/hugs/src/Plugin/Block/HugStatus.php

namespace Drupal\hugs\Plugin\Block;

use Drupal\block\BlockBase;

/**
 * Reports on hugability status.
 *
 * @Block(
 *   id = "hugs_status",
 *   admin_label = @Translation("Hug status"),
 *   category = @Translation("System")
 * )
 */
class HugStatus extends BlockBase {

  public function build() {
    return [
      '#markup' => $this->t('This is a hug-enabled site'),
    ];
  }
}

/modules/hugs/src/Plugin/Block/HugStatus.php

class HugStatus extends BlockBase {
  public function defaultConfiguration() {
    return ['enabled' => 1];
  }

  public function blockForm($form, FormStateInterface $form_state) {
    $form['enabled'] = [
      '#type' => 'checkbox',
      '#title' => $this->t('Hugging enabled'),
      '#default_value' => $this->configuration['enabled'],
    ];
    return $form;
  }

  public function blockSubmit($form, FormStateInterface $form_state) {
    $this->configuration['enabled'] = (bool)$form_state->getValue('enabled');
  }

  public function build() {
    $message = $this->configuration['enabled']
      ? $this->t('Now accepting hugs')
      : $this->t('No hugs :-(');

    return ['#markup' => $message];
  }
}

/modules/hugs/src/HugTracker.php

namespace Drupal\hugs;

use Drupal\Core\State\StateInterface;

class HugTracker {

  protected $state;

  public function __construct(StateInterface $state) {
    $this->state = $state;
  }

  public function addHug($target_name) {
    $this->state->set('hugs.last_recipient', $target_name);
    return $this;
  }

  public function getLastRecipient() {
    return $this->state->get('hugs.last_recipient');
  }
}

/modules/hugs/hugs.services.yml

services:
  hugs.hug_tracker:
    class: Drupal\hugs\HugTracker
    arguments: ['@state']

/modules/hugs/src/Controller/HugsController.php

namespace Drupal\hugs\Controller;
use Drupal\Core\Controller\ControllerBase;
use Drupal\hugs\HugTracker;
use Symfony\Component\DependencyInjection\ContainerInterface;

class HugsController extends ControllerBase {
  protected $hugTracker;

  public function __construct(HugTracker $tracker) {
    $this->hugTracker = $tracker;
  }

  public static function create(ContainerInterface $container) {
    return new static($container->get('hugs.hug_tracker'));
  }

  public function hug($to, $from, $count) {
    $this->hugTracker->addHug($to);
    $count = $count ?: $this->config('hugs.settings')->get('default_count');
    return [
      '#theme' => 'hug_page',
      '#from' => $from,
      '#to' => $to,
      '#count' => $count,
    ];
  }
}

/modules/hugs/src/Plugin/Block/HugStatus.php

namespace Drupal\hugs\Plugin\Block;

class HugStatus extends BlockBase implements ContainerFactoryPluginInterface {
  protected $hugTracker;

  public function __construct(array $configuration, $plugin_id, $plugin_definition,
              HugTracker $hugTracker) {
    parent::__construct($configuration, $plugin_id, $plugin_definition);
    $this->hugTracker = $hugTracker;
  }

  public static function create(ContainerInterface $container,
              array $configuration, $plugin_id, $plugin_definition) {
    return new static(
      $configuration, $plugin_id, $plugin_definition,
      $container->get('hugs.hug_tracker')
    );
  }

  public function build() {
    $message = $this->t('No hugs :-(');
    if ($this->configuration['enabled']) {
      $message = $this->t('@to was the last person hugged', [
        '@to' => $this->hugTracker->getLastRecipient()
      ]);
    }
    return ['#markup' => $message];
  }
  // ...
}

/modules/hugs/hugs.routing.yml

hugs.node:
  path: /node/{node}/hug
  defaults:
    _controller: 'Drupal\hugs\Controller\HugsController::nodeHug'
  requirements:
    _permission: 'access content'

/modules/hugs/src/Controller/HugsController.php

class HugsController extends ControllerBase {
  public function nodeHug(NodeInterface $node) {
    if ($node->isPublished()) {
      // These are the same!
      $body = $node->body->value;
      $body = $node->body[0]->value;

      // But we really want...
      $formatted = $node->body->processed;

      foreach ($node->field_tags as $tag) {
        $terms[] = $tag->entity->label();
      }

      $message = $this->t('Everyone hug @name because @reasons!', [
        '@name' => $node->getOwner()->label(), '@reasons' => implode(', ', $terms),
      ]);

      return [
        '#title' => $node->label() . ' (' . $node->bundle() . ')',
        '#markup' => $message . $formatted,
      ];
    }
    return ['#markup' => $this->t('Not published')];
  }
}

That should probably all be in a template...

Drupal 8

The Crash Course

@Crell

Just enough theory

PHP 4 architecture

HTTP Architecture

Symfony/HttpKernel architecture

HttpKernel pipeline

Controllers

Drupal in 2 steps:

Drupal in 2 (other) steps:

How do I...?

How do I...?

How do I...?

How do I...?

How do I...?

Definitions

Drupal 7 extensibility

Drupal 8 extensibility

Pluginified systems in Drupal 8

How do I...?

Services

How do I...?

Entities

Content entities

Drupal in 2 steps:

Guidelines

Larry Garfield