pager_default_initialize($total, $limit, $element = 0)
Initializes a pager.
This function sets up the necessary global variables so that the render system will correctly process #type 'pager' render arrays to output pagers that correspond to the items being displayed.
If the items being displayed result from a database query performed using Drupal's database API, and if you have control over the construction of the database query, you do not need to call this function directly; instead, you can simply extend the query object with the 'PagerSelectExtender' extender before executing it. For example:
$query = db_select('some_table')
->extend('Drupal\Core\Database\Query\PagerSelectExtender');
However, if you are using a different method for generating the items to be paged through, then you should call this function in preparation.
The following example shows how this function can be used in a controller that invokes an external datastore with an SQL-like syntax:
// First find the total number of items and initialize the pager.
$where = "status = 1";
$total = mymodule_select("SELECT COUNT(*) FROM data " . $where)->result();
$num_per_page = \Drupal::config('mymodule.settings')->get('num_per_page');
$page = pager_default_initialize($total, $num_per_page);
// Next, retrieve the items for the current page and put them into a
// render array.
$offset = $num_per_page * $page;
$result = mymodule_select("SELECT * FROM data " . $where . " LIMIT %d, %d", $offset, $num_per_page)->fetchAll();
$render = [];
$render[] = [
'#theme' => 'mymodule_results',
'#result' => $result,
];
// Finally, add the pager to the render array, and return.
$render[] = ['#type' => 'pager'];
return $render;
A second example involves a controller that invokes an external search service where the total number of matching results is provided as part of the returned set (so that we do not need a separate query in order to obtain this information). Here, we call pager_find_page() to calculate the desired offset before the search is invoked:
// Perform the query, using the requested offset from pager_find_page().
// This comes from a URL parameter, so here we are assuming that the URL
// parameter corresponds to an actual page of results that will exist
// within the set.
$page = pager_find_page();
$num_per_page = \Drupal::config('mymodule.settings')->get('num_per_page');
$offset = $num_per_page * $page;
$result = mymodule_remote_search($keywords, $offset, $num_per_page);
// Now that we have the total number of results, initialize the pager.
pager_default_initialize($result->total, $num_per_page);
// Create a render array with the search results.
$render = [];
$render[] = [
'#theme' => 'search_results',
'#results' => $result->data,
'#type' => 'remote',
];
// Finally, add the pager to the render array, and return.
$render[] = ['#type' => 'pager'];
return $render;
Parameters
int $total: The total number of items to be paged.
int $limit: The number of items the calling code will display per page.
int $element: (optional) An integer to distinguish between multiple pagers on one page.
Return value
int The number of the current page, within the pager represented by $element. This is determined from the URL query parameter \Drupal::request()->query->get('page), or 0 by default. However, if a page that does not correspond to the actual range of the result set was requested, this function will return the closest page actually within the result set.
File
- core/includes/pager.inc, line 127
- Functions to aid in presenting database results as a set of pages.
Code
function pager_default_initialize($total, $limit, $element = 0) {
global $pager_page_array, $pager_total, $pager_total_items, $pager_limits;
$page = pager_find_page($element);
// We calculate the total of pages as ceil(items / limit).
$pager_total_items[$element] = $total;
$pager_total[$element] = ceil($pager_total_items[$element] / $limit);
$pager_page_array[$element] = max(0, min($page, ((int) $pager_total[$element]) - 1));
$pager_limits[$element] = $limit;
return $pager_page_array[$element];
}
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