Multiple Caches Per Page
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.
Example 14-6. passing a cache_id to display()
<?php
require('Smarty.class.php');
$smarty = new Smarty;
$smarty->caching = true;
$my_cache_id = $_GET['article_id'];
$smarty->display('index.tpl',$my_cache_id);
?>
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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_ids 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
10 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 is_cached() and
clear_cache().
Example 14-7. passing a cache_id to is_cached()
<?php
require('Smarty.class.php');
$smarty = new Smarty;
$smarty->caching = true;
$my_cache_id = $_GET['article_id'];
if(!$smarty->is_cached('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);
?>
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You can clear all caches for a particular cache_id by passing null as the
first parameter to
clear_cache().
Example 14-8. clearing all caches for a particular cache_id
<?php
require('Smarty.class.php');
$smarty = new Smarty;
$smarty->caching = true;
// clear all caches with "sports" as the cache_id
$smarty->clear_cache(null,"sports");
$smarty->display('index.tpl',"sports");
?>
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In this manner, you can "group" your caches together by giving them the
same cache_id.
