Chris@0: <?php
Chris@0: 
Chris@0: /**
Chris@0:  * @file
Chris@0:  * Functions to aid in presenting database results as a set of pages.
Chris@0:  */
Chris@0: 
Chris@18: use Drupal\Core\Url;
Chris@0: use Drupal\Component\Utility\UrlHelper;
Chris@18: use Drupal\Component\Utility\Html;
Chris@0: 
Chris@0: /**
Chris@0:  * Returns the current page being requested for display within a pager.
Chris@0:  *
Chris@0:  * @param int $element
Chris@0:  *   (optional) An integer to distinguish between multiple pagers on one page.
Chris@0:  *
Chris@0:  * @return int
Chris@0:  *   The number of the current requested page, within the pager represented by
Chris@0:  *   $element. This is determined from the URL query parameter
Chris@0:  *   \Drupal::request()->query->get('page'), or 0 by default. Note that this
Chris@0:  *   number may differ from the actual page being displayed. For example, if a
Chris@0:  *   search for "example text" brings up three pages of results, but a user
Chris@0:  *   visits search/node/example+text?page=10, this function will return 10,
Chris@0:  *   even though the default pager implementation adjusts for this and still
Chris@0:  *   displays the third page of search results at that URL.
Chris@0:  *
Chris@0:  * @see pager_default_initialize()
Chris@0:  */
Chris@0: function pager_find_page($element = 0) {
Chris@0:   $page = \Drupal::request()->query->get('page', '');
Chris@0:   $page_array = explode(',', $page);
Chris@0:   if (!isset($page_array[$element])) {
Chris@0:     $page_array[$element] = 0;
Chris@0:   }
Chris@0:   return (int) $page_array[$element];
Chris@0: }
Chris@0: 
Chris@0: /**
Chris@0:  * Initializes a pager.
Chris@0:  *
Chris@0:  * This function sets up the necessary global variables so that the render
Chris@0:  * system will correctly process #type 'pager' render arrays to output pagers
Chris@0:  * that correspond to the items being displayed.
Chris@0:  *
Chris@0:  * If the items being displayed result from a database query performed using
Chris@0:  * Drupal's database API, and if you have control over the construction of the
Chris@0:  * database query, you do not need to call this function directly; instead, you
Chris@0:  * can simply extend the query object with the 'PagerSelectExtender' extender
Chris@0:  * before executing it. For example:
Chris@0:  * @code
Chris@0:  *   $query = db_select('some_table')
Chris@0:  *     ->extend('Drupal\Core\Database\Query\PagerSelectExtender');
Chris@0:  * @endcode
Chris@0:  *
Chris@0:  * However, if you are using a different method for generating the items to be
Chris@0:  * paged through, then you should call this function in preparation.
Chris@0:  *
Chris@0:  * The following example shows how this function can be used in a controller
Chris@0:  * that invokes an external datastore with an SQL-like syntax:
Chris@0:  * @code
Chris@0:  *   // First find the total number of items and initialize the pager.
Chris@0:  *   $where = "status = 1";
Chris@0:  *   $total = mymodule_select("SELECT COUNT(*) FROM data " . $where)->result();
Chris@0:  *   $num_per_page = \Drupal::config('mymodule.settings')->get('num_per_page');
Chris@0:  *   $page = pager_default_initialize($total, $num_per_page);
Chris@0:  *
Chris@0:  *   // Next, retrieve the items for the current page and put them into a
Chris@0:  *   // render array.
Chris@0:  *   $offset = $num_per_page * $page;
Chris@0:  *   $result = mymodule_select("SELECT * FROM data " . $where . " LIMIT %d, %d", $offset, $num_per_page)->fetchAll();
Chris@0:  *   $render = [];
Chris@0:  *   $render[] = [
Chris@0:  *     '#theme' => 'mymodule_results',
Chris@0:  *     '#result' => $result,
Chris@0:  *   ];
Chris@0:  *
Chris@0:  *   // Finally, add the pager to the render array, and return.
Chris@0:  *   $render[] = ['#type' => 'pager'];
Chris@0:  *   return $render;
Chris@0:  * @endcode
Chris@0:  *
Chris@0:  * A second example involves a controller that invokes an external search
Chris@0:  * service where the total number of matching results is provided as part of
Chris@0:  * the returned set (so that we do not need a separate query in order to obtain
Chris@0:  * this information). Here, we call pager_find_page() to calculate the desired
Chris@0:  * offset before the search is invoked:
Chris@0:  * @code
Chris@0:  *   // Perform the query, using the requested offset from pager_find_page().
Chris@0:  *   // This comes from a URL parameter, so here we are assuming that the URL
Chris@0:  *   // parameter corresponds to an actual page of results that will exist
Chris@0:  *   // within the set.
Chris@0:  *   $page = pager_find_page();
Chris@0:  *   $num_per_page = \Drupal::config('mymodule.settings')->get('num_per_page');
Chris@0:  *   $offset = $num_per_page * $page;
Chris@0:  *   $result = mymodule_remote_search($keywords, $offset, $num_per_page);
Chris@0:  *
Chris@0:  *   // Now that we have the total number of results, initialize the pager.
Chris@0:  *   pager_default_initialize($result->total, $num_per_page);
Chris@0:  *
Chris@0:  *   // Create a render array with the search results.
Chris@0:  *   $render = [];
Chris@0:  *   $render[] = [
Chris@0:  *     '#theme' => 'search_results',
Chris@0:  *     '#results' => $result->data,
Chris@0:  *     '#type' => 'remote',
Chris@0:  *   ];
Chris@0:  *
Chris@0:  *   // Finally, add the pager to the render array, and return.
Chris@0:  *   $render[] = ['#type' => 'pager'];
Chris@0:  *   return $render;
Chris@0:  * @endcode
Chris@0:  *
Chris@0:  * @param int $total
Chris@0:  *   The total number of items to be paged.
Chris@0:  * @param int $limit
Chris@0:  *   The number of items the calling code will display per page.
Chris@0:  * @param int $element
Chris@0:  *   (optional) An integer to distinguish between multiple pagers on one page.
Chris@0:  *
Chris@0:  * @return int
Chris@0:  *   The number of the current page, within the pager represented by $element.
Chris@0:  *   This is determined from the URL query parameter
Chris@0:  *   \Drupal::request()->query->get('page), or 0 by default. However, if a page
Chris@0:  *   that does not correspond to the actual range of the result set was
Chris@0:  *   requested, this function will return the closest page actually within the
Chris@0:  *   result set.
Chris@0:  */
Chris@0: function pager_default_initialize($total, $limit, $element = 0) {
Chris@0:   global $pager_page_array, $pager_total, $pager_total_items, $pager_limits;
Chris@0: 
Chris@0:   $page = pager_find_page($element);
Chris@0: 
Chris@0:   // We calculate the total of pages as ceil(items / limit).
Chris@0:   $pager_total_items[$element] = $total;
Chris@0:   $pager_total[$element] = ceil($pager_total_items[$element] / $limit);
Chris@0:   $pager_page_array[$element] = max(0, min($page, ((int) $pager_total[$element]) - 1));
Chris@0:   $pager_limits[$element] = $limit;
Chris@0:   return $pager_page_array[$element];
Chris@0: }
Chris@0: 
Chris@0: /**
Chris@0:  * Compose a URL query parameter array for pager links.
Chris@0:  *
Chris@0:  * @return array
Chris@0:  *   A URL query parameter array that consists of all components of the current
Chris@0:  *   page request except for those pertaining to paging.
Chris@0:  */
Chris@0: function pager_get_query_parameters() {
Chris@0:   $query = &drupal_static(__FUNCTION__);
Chris@0:   if (!isset($query)) {
Chris@0:     $query = UrlHelper::filterQueryParameters(\Drupal::request()->query->all(), ['page']);
Chris@0:   }
Chris@0:   return $query;
Chris@0: }
Chris@0: 
Chris@0: /**
Chris@0:  * Prepares variables for pager templates.
Chris@0:  *
Chris@0:  * Default template: pager.html.twig.
Chris@0:  *
Chris@0:  * Menu callbacks that display paged query results should use #type => pager
Chris@0:  * to retrieve a pager control so that users can view other results. Format a
Chris@0:  * list of nearby pages with additional query results.
Chris@0:  *
Chris@0:  * @param array $variables
Chris@0:  *   An associative array containing:
Chris@0:  *   - pager: A render element containing:
Chris@0:  *     - #tags: An array of labels for the controls in the pager.
Chris@0:  *     - #element: An optional integer to distinguish between multiple pagers on
Chris@0:  *       one page.
Chris@0:  *     - #parameters: An associative array of query string parameters to append
Chris@0:  *       to the pager links.
Chris@0:  *     - #route_parameters: An associative array of the route parameters.
Chris@0:  *     - #quantity: The number of pages in the list.
Chris@0:  */
Chris@0: function template_preprocess_pager(&$variables) {
Chris@0:   $element = $variables['pager']['#element'];
Chris@0:   $parameters = $variables['pager']['#parameters'];
Chris@0:   $quantity = $variables['pager']['#quantity'];
Chris@0:   $route_name = $variables['pager']['#route_name'];
Chris@0:   $route_parameters = isset($variables['pager']['#route_parameters']) ? $variables['pager']['#route_parameters'] : [];
Chris@0:   global $pager_page_array, $pager_total;
Chris@0: 
Chris@0:   // Nothing to do if there is only one page.
Chris@0:   if ($pager_total[$element] <= 1) {
Chris@0:     return;
Chris@0:   }
Chris@0: 
Chris@0:   $tags = $variables['pager']['#tags'];
Chris@0: 
Chris@0:   // Calculate various markers within this pager piece:
Chris@0:   // Middle is used to "center" pages around the current page.
Chris@0:   $pager_middle = ceil($quantity / 2);
Chris@0:   // current is the page we are currently paged to.
Chris@0:   $pager_current = $pager_page_array[$element] + 1;
Chris@0:   // first is the first page listed by this pager piece (re quantity).
Chris@0:   $pager_first = $pager_current - $pager_middle + 1;
Chris@0:   // last is the last page listed by this pager piece (re quantity).
Chris@0:   $pager_last = $pager_current + $quantity - $pager_middle;
Chris@0:   // max is the maximum page number.
Chris@0:   $pager_max = $pager_total[$element];
Chris@0:   // End of marker calculations.
Chris@0: 
Chris@0:   // Prepare for generation loop.
Chris@0:   $i = $pager_first;
Chris@0:   if ($pager_last > $pager_max) {
Chris@0:     // Adjust "center" if at end of query.
Chris@0:     $i = $i + ($pager_max - $pager_last);
Chris@0:     $pager_last = $pager_max;
Chris@0:   }
Chris@0:   if ($i <= 0) {
Chris@0:     // Adjust "center" if at start of query.
Chris@0:     $pager_last = $pager_last + (1 - $i);
Chris@0:     $i = 1;
Chris@0:   }
Chris@0:   // End of generation loop preparation.
Chris@0: 
Chris@0:   // Create the "first" and "previous" links if we are not on the first page.
Chris@0:   if ($pager_page_array[$element] > 0) {
Chris@0:     $items['first'] = [];
Chris@0:     $options = [
Chris@0:       'query' => pager_query_add_page($parameters, $element, 0),
Chris@0:     ];
Chris@18:     $items['first']['href'] = Url::fromRoute($route_name, $route_parameters, $options)->toString();
Chris@0:     if (isset($tags[0])) {
Chris@0:       $items['first']['text'] = $tags[0];
Chris@0:     }
Chris@0: 
Chris@0:     $items['previous'] = [];
Chris@0:     $options = [
Chris@0:       'query' => pager_query_add_page($parameters, $element, $pager_page_array[$element] - 1),
Chris@0:     ];
Chris@18:     $items['previous']['href'] = Url::fromRoute($route_name, $route_parameters, $options)->toString();
Chris@0:     if (isset($tags[1])) {
Chris@0:       $items['previous']['text'] = $tags[1];
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   if ($i != $pager_max) {
Chris@0:     // Add an ellipsis if there are further previous pages.
Chris@0:     if ($i > 1) {
Chris@0:       $variables['ellipses']['previous'] = TRUE;
Chris@0:     }
Chris@0:     // Now generate the actual pager piece.
Chris@0:     for (; $i <= $pager_last && $i <= $pager_max; $i++) {
Chris@0:       $options = [
Chris@0:         'query' => pager_query_add_page($parameters, $element, $i - 1),
Chris@0:       ];
Chris@18:       $items['pages'][$i]['href'] = Url::fromRoute($route_name, $route_parameters, $options)->toString();
Chris@0:       if ($i == $pager_current) {
Chris@0:         $variables['current'] = $i;
Chris@0:       }
Chris@0:     }
Chris@0:     // Add an ellipsis if there are further next pages.
Chris@0:     if ($i < $pager_max + 1) {
Chris@0:       $variables['ellipses']['next'] = TRUE;
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   // Create the "next" and "last" links if we are not on the last page.
Chris@0:   if ($pager_page_array[$element] < ($pager_max - 1)) {
Chris@0:     $items['next'] = [];
Chris@0:     $options = [
Chris@0:       'query' => pager_query_add_page($parameters, $element, $pager_page_array[$element] + 1),
Chris@0:     ];
Chris@18:     $items['next']['href'] = Url::fromRoute($route_name, $route_parameters, $options)->toString();
Chris@0:     if (isset($tags[3])) {
Chris@0:       $items['next']['text'] = $tags[3];
Chris@0:     }
Chris@0: 
Chris@0:     $items['last'] = [];
Chris@0:     $options = [
Chris@0:       'query' => pager_query_add_page($parameters, $element, $pager_max - 1),
Chris@0:     ];
Chris@18:     $items['last']['href'] = Url::fromRoute($route_name, $route_parameters, $options)->toString();
Chris@0:     if (isset($tags[4])) {
Chris@0:       $items['last']['text'] = $tags[4];
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   $variables['items'] = $items;
Chris@18:   $variables['heading_id'] = Html::getUniqueId('pagination-heading');
Chris@0: 
Chris@0:   // The rendered link needs to play well with any other query parameter used
Chris@0:   // on the page, like exposed filters, so for the cacheability all query
Chris@0:   // parameters matter.
Chris@0:   $variables['#cache']['contexts'][] = 'url.query_args';
Chris@0: }
Chris@0: 
Chris@0: /**
Chris@0:  * Gets the URL query parameter array of a pager link.
Chris@0:  *
Chris@0:  * Adds to or adjusts the 'page' URL query parameter so that if you follow the
Chris@0:  * link, you'll get page $index for pager $element on the page.
Chris@0:  *
Chris@0:  * The 'page' URL query parameter is a comma-delimited string, where each value
Chris@0:  * is the target content page for the corresponding pager $element. For
Chris@0:  * instance, if we have 5 pagers on a single page, and we want to have a link
Chris@0:  * to a page that should display the 6th content page for the 3rd pager, and
Chris@0:  * the 1st content page for all the other pagers, then the URL query will look
Chris@0:  * like this: ?page=0,0,5,0,0 (page numbering starts at zero).
Chris@0:  *
Chris@0:  * @param array $query
Chris@0:  *   An associative array of URL query parameters to add to.
Chris@0:  * @param int $element
Chris@0:  *   An integer to distinguish between multiple pagers on one page.
Chris@0:  * @param int $index
Chris@0:  *   The index of the target page, for the given element, in the pager array.
Chris@0:  *
Chris@0:  * @return array
Chris@0:  *   The altered $query parameter array.
Chris@0:  */
Chris@0: function pager_query_add_page(array $query, $element, $index) {
Chris@0:   global $pager_page_array;
Chris@0: 
Chris@0:   // Build the 'page' query parameter. This is built based on the current
Chris@0:   // page of each pager element (or NULL if the pager is not set), with the
Chris@0:   // exception of the requested page index for the current element.
Chris@0:   $max_element = max(array_keys($pager_page_array));
Chris@0:   $element_pages = [];
Chris@0:   for ($i = 0; $i <= $max_element; $i++) {
Chris@0:     $element_pages[] = ($i == $element) ? $index : (isset($pager_page_array[$i]) ? $pager_page_array[$i] : NULL);
Chris@0:   }
Chris@0:   $query['page'] = implode(',', $element_pages);
Chris@0: 
Chris@0:   // Merge the query parameters passed to this function with the parameters
Chris@0:   // from the current request. In case of collision, the parameters passed into
Chris@0:   // this function take precedence.
Chris@0:   if ($current_request_query = pager_get_query_parameters()) {
Chris@0:     $query = array_merge($current_request_query, $query);
Chris@0:   }
Chris@0:   return $query;
Chris@0: }