public function CacheExampleForm::buildForm in Examples for Developers 8

Same name and namespace in other branches

1. 3.x modules/cache_example/src/Form/CacheExampleForm.php \Drupal\cache_example\Form\CacheExampleForm::buildForm()

Form constructor.

Parameters

array $form: An associative array containing the structure of the form.

\Drupal\Core\Form\FormStateInterface $form_state: The current state of the form.

Return value

array The form structure.

Overrides FormInterface::buildForm

File

cache_example/src/Form/CacheExampleForm.php, line 74

Class

CacheExampleForm

Form with examples on how to use cache.

Namespace

Drupal\cache_example\Form

Code

public function buildForm(array $form, FormStateInterface $form_state) {

  // Log execution time.
  $start_time = microtime(TRUE);

  // Try to load the files count from cache. This function will accept two
  // arguments:
  // - cache object name (cid)
  // - cache bin, the (optional) cache bin (most often a database table) where
  //   the object is to be saved.
  //
  // cache_get() returns the cached object or FALSE if object does not exist.
  if ($cache = $this->cacheBackend
    ->get('cache_example_files_count')) {

    /*
     * Get cached data. Complex data types will be unserialized automatically.
     */
    $files_count = $cache->data;
  }
  else {

    // If there was no cached data available we have to search filesystem.
    // Recursively get all .PHP files from Drupal's core folder.
    $files_count = count($this->fileSystem
      ->scanDirectory('core', '/.php/'));

    // Since we have recalculated, we now need to store the new data into
    // cache. Complex data types will be automatically serialized before
    // being saved into cache.
    // Here we use the default setting and create an unexpiring cache item.
    // See below for an example that creates an expiring cache item.
    $this->cacheBackend
      ->set('cache_example_files_count', $files_count, CacheBackendInterface::CACHE_PERMANENT);
  }
  $end_time = microtime(TRUE);
  $duration = $end_time - $start_time;

  // Format intro message.
  $intro_message = '<p>' . $this
    ->t("This example will search Drupal's core folder and display a count of the PHP files in it.") . ' ';
  $intro_message .= $this
    ->t('This can take a while, since there are a lot of files to be searched.') . ' ';
  $intro_message .= $this
    ->t('We will search filesystem just once and save output to the cache. We will use cached data for later requests.') . '</p>';
  $intro_message .= '<p>' . $this
    ->t('<a href="@url">Reload this page</a> to see cache in action.', [
    '@url' => $this
      ->getRequest()
      ->getRequestUri(),
  ]) . ' ';
  $intro_message .= $this
    ->t('You can use the button below to remove cached data.') . '</p>';
  $form['file_search'] = [
    '#type' => 'fieldset',
    '#title' => $this
      ->t('File search caching'),
  ];
  $form['file_search']['introduction'] = [
    '#markup' => $intro_message,
  ];
  $color = empty($cache) ? 'red' : 'green';
  $retrieval = empty($cache) ? $this
    ->t('calculated by traversing the filesystem') : $this
    ->t('retrieved from cache');
  $form['file_search']['statistics'] = [
    '#type' => 'item',
    '#markup' => $this
      ->t('%count files exist in this Drupal installation; @retrieval in @time ms. <br/>(Source: <span style="color:@color;">@source</span>)', [
      '%count' => $files_count,
      '@retrieval' => $retrieval,
      '@time' => number_format($duration * 1000, 2),
      '@color' => $color,
      '@source' => empty($cache) ? $this
        ->t('actual file search') : $this
        ->t('cached'),
    ]),
  ];
  $form['file_search']['remove_file_count'] = [
    '#type' => 'submit',
    '#submit' => [
      '::expireFiles',
    ],
    '#value' => $this
      ->t('Explicitly remove cached file count'),
  ];
  $form['expiration_demo'] = [
    '#type' => 'fieldset',
    '#title' => $this
      ->t('Cache expiration settings'),
  ];
  $form['expiration_demo']['explanation'] = [
    '#markup' => $this
      ->t('A cache item can be set as CACHE_PERMANENT, meaning that it will only be removed when explicitly cleared, or it can have an expiration time (a Unix timestamp).'),
  ];
  $item = $this->cacheBackend
    ->get('cache_example_expiring_item', TRUE);
  if ($item == FALSE) {
    $item_status = $this
      ->t('Cache item does not exist');
  }
  else {
    $item_status = $item->valid ? $this
      ->t('Cache item exists and is set to expire at %time', [
      '%time' => $item->data,
    ]) : $this
      ->t('Cache_item is invalid');
  }
  $form['expiration_demo']['current_status'] = [
    '#type' => 'item',
    '#title' => $this
      ->t('Current status of cache item "cache_example_expiring_item"'),
    '#markup' => $item_status,
  ];
  $form['expiration_demo']['expiration'] = [
    '#type' => 'select',
    '#title' => $this
      ->t('Time before cache expiration'),
    '#options' => [
      'never_remove' => $this
        ->t('CACHE_PERMANENT'),
      -10 => $this
        ->t('Immediate expiration'),
      10 => $this
        ->t('10 seconds from form submission'),
      60 => $this
        ->t('1 minute from form submission'),
      300 => $this
        ->t('5 minutes from form submission'),
    ],
    '#default_value' => -10,
    '#description' => $this
      ->t('Any cache item can be set to only expire when explicitly cleared, or to expire at a given time.'),
  ];
  $form['expiration_demo']['create_cache_item'] = [
    '#type' => 'submit',
    '#value' => $this
      ->t('Create a cache item with this expiration'),
    '#submit' => [
      '::createExpiringItem',
    ],
  ];
  $form['cache_clearing'] = [
    '#type' => 'fieldset',
    '#title' => $this
      ->t('Expire and remove options'),
    '#description' => $this
      ->t("We have APIs to expire cached items and also to just remove them. Unfortunately, they're all the same API, cache_clear_all"),
  ];
  $form['cache_clearing']['cache_clear_type'] = [
    '#type' => 'radios',
    '#title' => $this
      ->t('Type of cache clearing to do'),
    '#options' => [
      'expire' => $this
        ->t('Remove items from the "cache" bin that have expired'),
      'remove_all' => $this
        ->t('Remove all items from the "cache" bin regardless of expiration'),
      'remove_tag' => $this
        ->t('Remove all items in the "cache" bin with the tag "cache_example" set to 1'),
    ],
    '#default_value' => 'expire',
  ];

  // Submit button to clear cached data.
  $form['cache_clearing']['clear_expired'] = [
    '#type' => 'submit',
    '#value' => $this
      ->t('Clear or expire cache'),
    '#submit' => [
      '::cacheClearing',
    ],
    '#access' => $this->currentUser
      ->hasPermission('administer site configuration'),
  ];
  return $form;
}