336 lines
12 KiB
PHP
336 lines
12 KiB
PHP
<?php
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/**
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* @file
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* Functions to aid in presenting database results as a set of pages.
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*/
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use Drupal\Core\Template\Attribute;
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use Drupal\Component\Utility\UrlHelper;
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/**
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* Returns the current page being requested for display within a pager.
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*
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* @param $element
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* An optional integer to distinguish between multiple pagers on one page.
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*
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* @return
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* The number of the current requested page, within the pager represented by
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* $element. This is determined from the URL query parameter
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* \Drupal::request()->query->get('page'), or 0 by default. Note that this
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* number may differ from the actual page being displayed. For example, if a
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* search for "example text" brings up three pages of results, but a users
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* visits search/node/example+text?page=10, this function will return 10, even
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* though the default pager implementation adjusts for this and still displays
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* the third page of search results at that URL.
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*
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* @see pager_default_initialize()
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*/
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function pager_find_page($element = 0) {
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$page = \Drupal::request()->query->get('page', '');
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$page_array = explode(',', $page);
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if (!isset($page_array[$element])) {
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$page_array[$element] = 0;
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}
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return (int) $page_array[$element];
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}
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/**
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* Initializes a pager for _theme('pager').
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*
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* This function sets up the necessary global variables so that future calls
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* to _theme('pager') will render a pager that correctly corresponds to the
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* items being displayed.
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*
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* If the items being displayed result from a database query performed using
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* Drupal's database API, and if you have control over the construction of the
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* database query, you do not need to call this function directly; instead, you
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* can simply extend the query object with the 'PagerSelectExtender' extender
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* before executing it. For example:
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* @code
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* $query = db_select('some_table')
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* ->extend('Drupal\Core\Database\Query\PagerSelectExtender');
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* @endcode
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*
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* However, if you are using a different method for generating the items to be
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* paged through, then you should call this function in preparation.
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*
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* The following example shows how this function can be used in a page callback
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* that invokes an external datastore with an SQL-like syntax:
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* @code
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* // First find the total number of items and initialize the pager.
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* $where = "status = 1";
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* $total = mymodule_select("SELECT COUNT(*) FROM data " . $where)->result();
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* $num_per_page = \Drupal::config('mymodule.settings')->get('num_per_page');
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* $page = pager_default_initialize($total, $num_per_page);
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*
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* // Next, retrieve and display the items for the current page.
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* $offset = $num_per_page * $page;
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* $result = mymodule_select("SELECT * FROM data " . $where . " LIMIT %d, %d", $offset, $num_per_page)->fetchAll();
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* $output = drupal_render(
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* '#theme' => 'mymodule_results',
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* '#result' => $result,
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* );
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*
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* // Finally, display the pager controls, and return.
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* $pager = array('#type' => 'pager');
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* $output .= drupal_render($pager);
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* return $output;
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* @endcode
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*
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* A second example involves a page callback that invokes an external search
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* service where the total number of matching results is provided as part of
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* the returned set (so that we do not need a separate query in order to obtain
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* this information). Here, we call pager_find_page() to calculate the desired
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* offset before the search is invoked:
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* @code
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* // Perform the query, using the requested offset from pager_find_page().
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* // This comes from a URL parameter, so here we are assuming that the URL
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* // parameter corresponds to an actual page of results that will exist
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* // within the set.
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* $page = pager_find_page();
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* $num_per_page = \Drupal::config('mymodule.settings')->get('num_per_page');
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* $offset = $num_per_page * $page;
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* $result = mymodule_remote_search($keywords, $offset, $num_per_page);
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*
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* // Now that we have the total number of results, initialize the pager.
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* pager_default_initialize($result->total, $num_per_page);
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*
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* // Display the search results.
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* $search_results = array(
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* '#theme' => 'search_results',
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* '#results' => $result->data,
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* '#type' => 'remote',
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* );
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* $output = drupal_render($search_results);
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*
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* // Finally, display the pager controls, and return.
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* $pager = array('#type' => 'pager');
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* $output .= drupal_render($pager);
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* return $output;
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* @endcode
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*
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* @param $total
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* The total number of items to be paged.
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* @param $limit
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* The number of items the calling code will display per page.
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* @param $element
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* An optional integer to distinguish between multiple pagers on one page.
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*
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* @return
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* The number of the current page, within the pager represented by $element.
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* This is determined from the URL query parameter
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* \Drupal::request()->query->get('page), or 0 by default. However, if a page
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* that does not correspond to the actual range of the result set was
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* requested, this function will return the closest page actually within the
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* result set.
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*/
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function pager_default_initialize($total, $limit, $element = 0) {
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global $pager_page_array, $pager_total, $pager_total_items, $pager_limits;
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$page = pager_find_page($element);
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// We calculate the total of pages as ceil(items / limit).
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$pager_total_items[$element] = $total;
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$pager_total[$element] = ceil($pager_total_items[$element] / $limit);
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$pager_page_array[$element] = max(0, min($page, ((int) $pager_total[$element]) - 1));
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$pager_limits[$element] = $limit;
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return $pager_page_array[$element];
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}
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/**
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* Compose a URL query parameter array for pager links.
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*
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* @return
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* A URL query parameter array that consists of all components of the current
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* page request except for those pertaining to paging.
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*/
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function pager_get_query_parameters() {
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$query = &drupal_static(__FUNCTION__);
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if (!isset($query)) {
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$query = UrlHelper::filterQueryParameters(\Drupal::request()->query->all(), array('page'));
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}
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return $query;
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}
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/**
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* Prepares variables for pager templates.
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*
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* Default template: pager.html.twig.
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*
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* Menu callbacks that display paged query results should use #type => pager
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* to retrieve a pager control so that users can view other results. Format a
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* list of nearby pages with additional query results.
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*
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* @param array $variables
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* An associative array containing:
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* - pager: A render element containing:
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* - #tags: An array of labels for the controls in the pager.
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* - #element: An optional integer to distinguish between multiple pagers on
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* one page.
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* - #parameters: An associative array of query string parameters to append to
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* the pager links.
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* - #quantity: The number of pages in the list.
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*/
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function template_preprocess_pager(&$variables) {
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$element = $variables['pager']['#element'];
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$parameters = $variables['pager']['#parameters'];
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$quantity = $variables['pager']['#quantity'];
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global $pager_page_array, $pager_total;
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// Nothing to do if there is only one page.
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if ($pager_total[$element] <= 1) {
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return;
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}
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$tags = $variables['pager']['#tags'];
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// Calculate various markers within this pager piece:
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// Middle is used to "center" pages around the current page.
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$pager_middle = ceil($quantity / 2);
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// current is the page we are currently paged to
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$pager_current = $pager_page_array[$element] + 1;
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// first is the first page listed by this pager piece (re quantity)
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$pager_first = $pager_current - $pager_middle + 1;
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// last is the last page listed by this pager piece (re quantity)
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$pager_last = $pager_current + $quantity - $pager_middle;
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// max is the maximum page number
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$pager_max = $pager_total[$element];
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// End of marker calculations.
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// Prepare for generation loop.
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$i = $pager_first;
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if ($pager_last > $pager_max) {
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// Adjust "center" if at end of query.
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$i = $i + ($pager_max - $pager_last);
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$pager_last = $pager_max;
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}
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if ($i <= 0) {
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// Adjust "center" if at start of query.
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$pager_last = $pager_last + (1 - $i);
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$i = 1;
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}
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// End of generation loop preparation.
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// Create the "first" and "previous" links if we are not on the first page.
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if ($pager_page_array[$element] > 0) {
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$items['first'] = array();
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$options = array(
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'query' => pager_query_add_page($parameters, $element, 0),
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);
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$items['first']['href'] = \Drupal::url('<current>', [], $options);
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if (isset($tags[0])) {
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$items['first']['text'] = $tags[0];
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}
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$items['previous'] = array();
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$options = array(
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'query' => pager_query_add_page($parameters, $element, $pager_page_array[$element] - 1),
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);
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$items['previous']['href'] = \Drupal::url('<current>', [], $options);
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if (isset($tags[1])) {
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$items['previous']['text'] = $tags[1];
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}
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}
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if ($i != $pager_max) {
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// Add an ellipsis if there are further previous pages.
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if ($i > 1) {
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$variables['ellipses']['previous'] = TRUE;
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}
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// Now generate the actual pager piece.
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for (; $i <= $pager_last && $i <= $pager_max; $i++) {
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$options = array(
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'query' => pager_query_add_page($parameters, $element, $i - 1),
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);
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$items['pages'][$i]['href'] = \Drupal::url('<current>', [], $options);
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if ($i == $pager_current) {
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$variables['current'] = $i;
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}
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}
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// Add an ellipsis if there are further next pages.
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if ($i < $pager_max) {
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$variables['ellipses']['next'] = TRUE;
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}
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}
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// Create the "next" and "last" links if we are not on the last page.
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if ($pager_page_array[$element] < ($pager_max - 1)) {
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$items['next'] = array();
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$options = array(
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'query' => pager_query_add_page($parameters, $element, $pager_page_array[$element] + 1),
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);
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$items['next']['href'] = \Drupal::url('<current>', [], $options);
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if (isset($tags[3])) {
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$items['next']['text'] = $tags[3];
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}
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$items['last'] = array();
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$options = array(
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'query' => pager_query_add_page($parameters, $element, $pager_max - 1),
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);
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$items['last']['href'] = \Drupal::url('<current>', [], $options);
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if (isset($tags[4])) {
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$items['last']['text'] = $tags[4];
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}
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}
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$variables['items'] = $items;
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}
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/**
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* Adds the 'page' parameter to the query parameter array of a pager link.
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*
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* @param array $query
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* An associative array of query parameters to add to.
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* @param integer $element
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* An integer to distinguish between multiple pagers on one page.
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* @param integer $index
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* The index of the target page in the pager array.
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*
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* @return array
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* The altered $query parameter array.
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*
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* @todo Document the pager/element/index architecture and logic. It is not
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* clear what is happening in this function as well as pager_load_array(),
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* and whether this can be simplified in any way.
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*/
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function pager_query_add_page(array $query, $element, $index) {
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global $pager_page_array;
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// Determine the first result to display on the linked page.
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$page_new = pager_load_array($index, $element, $pager_page_array);
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$page = \Drupal::request()->query->get('page', '');
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if ($new_page = implode(',', pager_load_array($page_new[$element], $element, explode(',', $page)))) {
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$query['page'] = $new_page;
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}
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// Merge the query parameters passed to this function with the parameters
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// from the current request. In case of collision, the parameters passed
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// into this function take precedence.
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if ($current_request_query = pager_get_query_parameters()) {
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$query = array_merge($current_request_query, $query);
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}
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return $query;
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}
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/**
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* Helper function
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*
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* Copies $old_array to $new_array and sets $new_array[$element] = $value
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* Fills in $new_array[0 .. $element - 1] = 0
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*/
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function pager_load_array($value, $element, $old_array) {
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$new_array = $old_array;
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// Look for empty elements.
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for ($i = 0; $i < $element; $i++) {
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if (empty($new_array[$i])) {
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// Load found empty element with 0.
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$new_array[$i] = 0;
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}
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}
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// Update the changed element.
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$new_array[$element] = (int) $value;
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return $new_array;
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}
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