Advanced usage

Custom data source adapters

At some point you may run across a data type that is not covered by the packaged adapters. In this case, you will need to write your own.

To do so, you must implement Zend\Paginator\Adapter\AdapterInterface. There are two methods required to do this:

• count() : int
• getItems(int $offset, int $itemCountPerPage) | array

Additionally, you'll typically implement a constructor that takes your data source as a parameter.

If you've ever used the SPL interface Countable, you're familiar with count(). As used with zend-paginator, this is the total number of items in the data collection; Zend\Paginator\Paginator::countAllItems proxies to this method.

When retrieving items for the current page, Zend\Paginator\Paginator calls on your adapter's getItems() method, providing it with an offset and the number of items to display per page; your job is to return the appropriate slice of data. For an array, that would be:

return array_slice($this->array, $offset, $itemCountPerPage);

Take a look at the packaged adapters for ideas of how you might go about implementing your own.

Custom scrolling styles

Creating your own scrolling style requires that you implement Zend\Paginator\ScrollingStyle\ScrollingStyleInterface, which defines a single method:

getPages(Paginator $paginator, int $pageRange = null) : array

This method should calculate a lower and upper bound for page numbers within the range of so-called "local" pages (that is, pages that are nearby the current page).

Unless it extends another scrolling style (see Zend\Paginator\ScrollingStyle\Elastic for an example), your custom scrolling style will inevitably end with something similar to the following line of code:

return $paginator->getPagesInRange($lowerBound, $upperBound);

There's nothing special about this call; it's merely a convenience method to check the validity of the lower and upper bound and return an array with the range to the paginator.

When you're ready to use your new scrolling style, you'll need to notif Zend\Paginator\Paginator:

use My\Paginator\ScrollingStyle;
use Zend\Paginator\Paginator;
use Zend\ServiceManager\Factory\InvokableFactory;

$manager = Paginator::getScrollingStyleManager();
$manager->setAlias('my-style', ScrollingStyle::class);
$manager->setFactory(ScrollingStyle::class, InvokableFactory::class);

Caching features

Installation Requirements

The caching features depends on the zend-cache component, so be sure to have it installed before getting started:

$ composer require zendframework/zend-cache

Zend\Paginator\Paginator can be told to cache the data it has already used, preventing the adapter from fetching on next request. To tell paginator to automatically cache the adapter's data, pass a pre-configured zend-cache adapter to the static setCache() method:

use Zend\Cache\StorageFactory;
use Zend\Paginator\Paginator;

$cache = StorageFactory::adapterFactory('filesystem', [
    'cache_dir' => '/tmp',
    'ttl'       => 3600,
    'plugins'   => [ 'serializer' ],
]);
Paginator::setCache($cache);

As long as the Paginator class has been seeded with a cache storage object, the data any instance generates will be cached. If you want to disable caching, call setCacheEnabled() with a boolean false on a concrete instance:

use Zend\Paginator\Paginator;

// $cache is a Zend\Cache\Storage\StorageInterface instance
Paginator::setCache($cache);

// ... later on the script:
$paginator->setCacheEnabled(false);
// cache is now disabled for this instance.

When a cache is set, data are automatically stored in it and pulled out from it. It then can be useful to empty the cache manually. You can get this done by calling clearPageItemCache($pageNumber). If you don't pass any parameter, the whole cache will be empty. You can optionally pass a parameter representing the page number to empty in the cache:

use Zend\Paginator\Paginator;

// $cache is a Zend\Cache\Storage\StorageInterface instance
Paginator::setCache($cache);

// $paginator is a fully configured Paginator instance:
$items = $paginator->getCurrentItems();

$page3Items = $paginator->getItemsByPage(3);
// page 3 is now in cache

// clear the cache of the results for page 3
$paginator->clearPageItemCache(3);

// clear all the cache data
$paginator->clearPageItemCache();

Changing the item count per page will empty the whole cache as it would have become invalid:

use Zend\Paginator\Paginator;

// $cache is a Zend\Cache\Storage\StorageInterface instance
Paginator::setCache($cache);

// Fetch some items from an instance:
$items = $paginator->getCurrentItems();

// Changing item count flushes the cache:
$paginator->setItemCountPerPage(2);

It is also possible to see the data in cache and ask for it directly. getPageItemCache() can be used for that:

use Zend\Paginator\Paginator;

// $cache is a Zend\Cache\Storage\StorageInterface instance
Paginator::setCache($cache);

// Set the item count:
$paginator->setItemCountPerPage(3);

// Fetch some items:
$items = $paginator->getCurrentItems();
$otherItems = $paginator->getItemsPerPage(4);

// See the cached items as a two-dimensional array:
var_dump($paginator->getPageItemCache());