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.
  • #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/pager.inc, line 185

Functions to aid in presenting database results as a set of pages.

Code

function template_preprocess_pager(&$variables) {
  $element = $variables['pager']['#element'];
  $parameters = $variables['pager']['#parameters'];
  $quantity = empty($variables['pager']['#quantity']) ? 0 : $variables['pager']['#quantity'];
  $route_name = $variables['pager']['#route_name'];
  $route_parameters = isset($variables['pager']['#route_parameters']) ? $variables['pager']['#route_parameters'] : [];

  /* @var $pager_manager \Drupal\Core\Pager\PagerManagerInterface */
  $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'] = $tags[1];
    }
  }
  if ($i != $pager_max) {

    // 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;
      }
    }

    // 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');

  // 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';
}