function template_preprocess_pager

Prepares variables for pager templates.

Default template: pager.html.twig.

Menu callbacks that display paged query results should use #type => pager to retrieve a pager control so that users can view other results. Format a list of nearby pages with additional query results.

Parameters

array $variables: An associative array containing:

• pager: A render element containing:
  • #tags: An array of labels for the controls in the pager.
  • #element: An optional integer to distinguish between multiple pagers on one page.
  • #pagination_heading_level: An optional heading level for the pager.
  • #parameters: An associative array of query string parameters to append to the pager links.
  • #route_parameters: An associative array of the route parameters.
  • #quantity: The number of pages in the list.

File

core/includes/theme.inc, line 1602

Code

function template_preprocess_pager(&$variables) : void {
    $element = $variables['pager']['#element'];
    $parameters = $variables['pager']['#parameters'];
    $quantity = empty($variables['pager']['#quantity']) ? 0 : $variables['pager']['#quantity'];
    $route_name = $variables['pager']['#route_name'];
    $route_parameters = $variables['pager']['#route_parameters'] ?? [];
    
    /** @var \Drupal\Core\Pager\PagerManagerInterface $pager_manager */
    $pager_manager = \Drupal::service('pager.manager');
    $pager = $pager_manager->getPager($element);
    // Nothing to do if there is no pager.
    if (!isset($pager)) {
        return;
    }
    $pager_max = $pager->getTotalPages();
    // Nothing to do if there is only one page.
    if ($pager_max <= 1) {
        return;
    }
    $tags = $variables['pager']['#tags'];
    // Calculate various markers within this pager piece:
    // Middle is used to "center" pages around the current page.
    $pager_middle = ceil($quantity / 2);
    $current_page = $pager->getCurrentPage();
    // The current pager is the page we are currently paged to.
    $pager_current = $current_page + 1;
    // The first pager is the first page listed by this pager piece (re quantity).
    $pager_first = $pager_current - $pager_middle + 1;
    // The last is the last page listed by this pager piece (re quantity).
    $pager_last = $pager_current + $quantity - $pager_middle;
    // End of marker calculations.
    // Prepare for generation loop.
    $i = $pager_first;
    if ($pager_last > $pager_max) {
        // Adjust "center" if at end of query.
        $i = $i + ($pager_max - $pager_last);
        $pager_last = $pager_max;
    }
    if ($i <= 0) {
        // Adjust "center" if at start of query.
        $pager_last = $pager_last + (1 - $i);
        $i = 1;
    }
    // End of generation loop preparation.
    // Create the "first" and "previous" links if we are not on the first page.
    if ($current_page > 0) {
        $items['first'] = [];
        $items['first']['attributes'] = new Attribute();
        $options = [
            'query' => $pager_manager->getUpdatedParameters($parameters, $element, 0),
        ];
        $items['first']['href'] = Url::fromRoute($route_name, $route_parameters, $options)->toString();
        if (isset($tags[0])) {
            $items['first']['text'] = $tags[0];
        }
        $items['previous'] = [];
        $items['previous']['attributes'] = new Attribute();
        $options = [
            'query' => $pager_manager->getUpdatedParameters($parameters, $element, $current_page - 1),
        ];
        $items['previous']['href'] = Url::fromRoute($route_name, $route_parameters, $options)->toString();
        if (isset($tags[1])) {
            $items['previous']['text'] = $tags[1];
        }
    }
    // Add an ellipsis if there are further previous pages.
    if ($i > 1) {
        $variables['ellipses']['previous'] = TRUE;
    }
    // Now generate the actual pager piece.
    for (; $i <= $pager_last && $i <= $pager_max; $i++) {
        $options = [
            'query' => $pager_manager->getUpdatedParameters($parameters, $element, $i - 1),
        ];
        $items['pages'][$i]['href'] = Url::fromRoute($route_name, $route_parameters, $options)->toString();
        $items['pages'][$i]['attributes'] = new Attribute();
        if ($i == $pager_current) {
            $variables['current'] = $i;
            $items['pages'][$i]['attributes']->setAttribute('aria-current', 'page');
        }
    }
    // Add an ellipsis if there are further next pages.
    if ($i < $pager_max + 1) {
        $variables['ellipses']['next'] = TRUE;
    }
    // Create the "next" and "last" links if we are not on the last page.
    if ($current_page < $pager_max - 1) {
        $items['next'] = [];
        $items['next']['attributes'] = new Attribute();
        $options = [
            'query' => $pager_manager->getUpdatedParameters($parameters, $element, $current_page + 1),
        ];
        $items['next']['href'] = Url::fromRoute($route_name, $route_parameters, $options)->toString();
        if (isset($tags[3])) {
            $items['next']['text'] = $tags[3];
        }
        $items['last'] = [];
        $items['last']['attributes'] = new Attribute();
        $options = [
            'query' => $pager_manager->getUpdatedParameters($parameters, $element, $pager_max - 1),
        ];
        $items['last']['href'] = Url::fromRoute($route_name, $route_parameters, $options)->toString();
        if (isset($tags[4])) {
            $items['last']['text'] = $tags[4];
        }
    }
    $variables['items'] = $items;
    $variables['heading_id'] = Html::getUniqueId('pagination-heading');
    $variables['pagination_heading_level'] = $variables['pager']['#pagination_heading_level'] ?? 'h4';
    if (!preg_match('/^h[1-6]$/', $variables['pagination_heading_level'])) {
        $variables['pagination_heading_level'] = 'h4';
    }
    // The rendered link needs to play well with any other query parameter used
    // on the page, like exposed filters, so for the cacheability all query
    // parameters matter.
    $variables['#cache']['contexts'][] = 'url.query_args';
}