function CacheExampleForm::buildForm

Overrides FormInterface::buildForm

File

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

Class

CacheExampleForm

Form with examples on how to use cache.

Namespace

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;
}