You can have multiple cache files for a single call to
display()
or fetch().
Let's say that a call to display('index.tpl') may have
several different output contents depending on some condition, and you want
separate caches for each one. You can do this by passing a
$cache_id as the second parameter to the
function call.
Пример 15.6. Passing a $cache_id to display()
<?php
require('Smarty.class.php');
$smarty = new Smarty;
$smarty->setCaching(Smarty::CACHING_LIFETIME_CURRENT);
$my_cache_id = $_GET['article_id'];
$smarty->display('index.tpl', $my_cache_id);
?>
Above, we are passing the variable $my_cache_id to
display()
as the $cache_id. For each unique value of
$my_cache_id, a separate cache will be
generated for index.tpl. In this example,
article_id was passed in the
URL and is used as the $cache_id.
Technical Note
Be very cautious when passing values from a client (web browser) into
Smarty or any PHP application. Although the above example of using the
article_id from the URL looks handy, it could have bad consequences. The
$cache_id is used to create a directory on the file
system, so if the user
decided to pass an extremely large value for article_id, or write a script
that sends random article_id's at a rapid pace, this could possibly cause
problems at the server level. Be sure to sanitize any data passed in before
using it. In this instance, maybe you know the article_id has a length of
ten characters and is made up of alpha-numerics only, and must be a valid
article_id in the database. Check for this!
Be sure to pass the same $cache_id as the
second parameter to
isCached() and
clearCache().
Пример 15.7. Passing a cache_id to isCached()
<?php
require('Smarty.class.php');
$smarty = new Smarty;
$smarty->setCaching(Smarty::CACHING_LIFETIME_CURRENT);
$my_cache_id = $_GET['article_id'];
if(!$smarty->isCached('index.tpl',$my_cache_id)) {
// No cache available, do variable assignments here.
$contents = get_database_contents();
$smarty->assign($contents);
}
$smarty->display('index.tpl',$my_cache_id);
?>
You can clear all caches for a particular $cache_id
by passing NULL as the
first parameter to
clearCache().
Пример 15.8. Clearing all caches for a particular $cache_id
<?php
require('Smarty.class.php');
$smarty = new Smarty;
$smarty->setCaching(Smarty::CACHING_LIFETIME_CURRENT);
// clear all caches with "sports" as the $cache_id
$smarty->clearCache(null,'sports');
$smarty->display('index.tpl','sports');
?>
In this manner, you can “group” your caches together by giving
them the same $cache_id.