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
are two methods required to do this:
count() : int
getItems(int $offset, int $itemCountPerPage) | array
Additionally, you'll typically implement a constructor that takes your data source as a parameter.
If you've ever used the SPL interface Countable,
you're familiar with
count(). As used with zend-paginator, this is the total
number of items in the data collection;
proxies to this method.
When retrieving items for the current page,
Zend\Paginator\Paginator calls on
getItems() method, providing it with an offset and the number
of items to display per page; your job is to return the appropriate slice of
data. For an array, that would be:
return array_slice($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
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
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);
The caching features depends on the zend-cache component, so be sure to have it installed before getting started:
bash $ 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
to the static
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: $paginator->setCacheEnabled(false); // cache is now disabled for this instance.
When a cache is set, data are automatically stored in it and pulled out from it.
It then can be useful to empty the cache manually. You can get this done by
clearPageItemCache($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());
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