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:
- getItems($offset, $itemCountPerPage)
Additionally, you’ll want to implement a constructor that takes your data source as a parameter and stores it as a protected or private property. How you wish to go about doing this specifically is up to you.
If you’ve ever used the SPL interface Countable, you’re familiar with
count(). As used with
Zend\Paginator, this is the total number of items in the data collection. Additionally, the
instance provides a method
countAllItems() that proxies to the adapter
getItems() method is only slightly more complicated. For this, your adapter is supplied with an offset and
the number of items to display per page. You must return the appropriate slice of data. For an array, that would
return array_slice($this->_array, $offset, $itemCountPerPage);
Take a look at the packaged adapters (all of which implement the
Zend\Paginator\Adapter\AdapterInterface) for ideas of
how you might go about implementing your own.
Custom scrolling styles¶
Creating your own scrolling style requires that you implement
defines a single method,
public function getPages(Zend\Paginator\Paginator $paginator, $pageRange = null);
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 of the range to the paginator.
When you’re ready to use your new scrolling style, you’ll need to tell
Zend\Paginator\Paginator what directory to look
in. To do that, do the following:
$manager = Zend\Paginator\Paginator::getScrollingStyleManager(); $manager->setInvokableClass('my-style', 'My\Paginator\ScrollingStyle');
Zend\Paginator\Paginator can be told to cache the data it has already passed on, preventing the adapter from fetching
them each time they are used. To tell paginator to automatically cache the adapter’s data, just pass to its
setCache() method a pre-configured cache object implementing the
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$cache = StorageFactory::adapterFactory('filesystem', array( 'cache_dir' => '/tmp', 'ttl' => 3600, 'plugins' => array( 'serializer' ), )); Zend\Paginator\Paginator::setCache($cache);
As long as
Zend\Paginator\Paginator has been seeded with a cache storage object the data it generates will be cached.
Sometimes you would like not to cache data even if you already passed a cache instance. You should then use
setCacheEnable() for that.
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// $cache is a Zend\Cache\Storage\StorageInterface instance Zend\Paginator\Paginator::setCache($cache); // ... later on the script $paginator->setCacheEnable(false); // cache is now disabled
When a cache is set, data are automatically stored in it and pulled out from it. It then can be useful to empty the
cache manually. You can get this done by calling
clearPageItemCache($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:
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// $cache is a Zend\Cache\Storage\StorageInterface instance Zend\Paginator\Paginator::setCache($cache); // $paginator is a fully configured Zend\Paginator\Paginator instance $items = $paginator->getCurrentItems(); // page 1 is now in cache $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:
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// $cache is a Zend\Cache\Storage\StorageInterface instance Zend\Paginator\Paginator::setCache($cache); // fetch some items // $paginator is a fully configured Zend\Paginator\Paginator instance $items = $paginator->getCurrentItems(); // all the cache data will be flushed: $paginator->setItemCountPerPage(2);
It is also possible to see the data in cache and ask for them directly.
getPageItemCache() can be used for
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// $cache is a Zend\Cache\Storage\StorageInterface instance Zend\Paginator\Paginator::setCache($cache); // $paginator is a fully configured Zend\Paginator\Paginator instance $paginator->setItemCountPerPage(3); // fetch some items $items = $paginator->getCurrentItems(); $otherItems = $paginator->getItemsPerPage(4); // see the cached items as a two-dimension array: var_dump($paginator->getPageItemCache());