Flushable
Introduction
Allows a class to define it's own flush functionality, which is triggered when flush=1 is requested in the URL.
FlushMiddleware is run before a request is made, calling flush() statically on all
implementors of Flushable.
Flushable implementers might also be triggered automatically on deploy if you have SS_FLUSH_ON_DEPLOY environment
variable defined. In that case even if you don't manually pass flush=1 parameter, the first request after deploy
will still be calling Flushable::flush on those entities.
Usage
To use this API, you need to make your class implement Flushable, and define a flush() static function,
this defines the actions that need to be executed on a flush request.
Using with cache
This example uses Cache in some custom code, and the same cache is cleaned on flush:
namespace App\Model;
use Psr\SimpleCache\CacheInterface;
use SilverStripe\Core\Flushable;
use SilverStripe\Core\Injector\Injector;
use SilverStripe\ORM\DataObject;
class MyClass extends DataObject implements Flushable
{
public static function flush()
{
Injector::inst()->get(CacheInterface::class . '.mycache')->clear();
}
public function getMyCachedContent()
{
$cache = Injector::inst()->get(CacheInterface::class . '.mycache')
$something = $cache->get('mykey');
if (!$something) {
$something = 'value to be cached';
$cache->set('mykey', $something);
}
return $something;
}
}Using with filesystem
Another example, some temporary files are created in a directory in assets, and are deleted on flush. This would be
useful in an example like GD or Imagick generating resampled images, but we want to delete any cached images on
flush so they are re-created on demand.
namespace App\Model;
use SilverStripe\Core\Flushable;
use SilverStripe\ORM\DataObject;
class MyClass extends DataObject implements Flushable
{
public static function flush()
{
foreach (glob(ASSETS_PATH . '/_tempfiles/*.jpg') as $file) {
unlink($file);
}
}
}