smarty/docs/api/caching/multiple-caches-per-template.md

Multiple caches per template

Introduction

You can have multiple cache files for a single call to display() or fetch().

Let's say that a call to $smarty->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:

<?php
use Smarty\Smarty;
$smarty = new Smarty;

$smarty->setCaching(Smarty::CACHING_LIFETIME_CURRENT);

$my_cache_id = (int) $_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.

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 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 example, you might want to check if the article_id is a valid ID in the database.

Be sure to pass the same $cache_id as the second parameter to isCached() and clearCache().

<?php
use Smarty\Smarty;
$smarty = new Smarty;

$smarty->setCaching(Smarty::CACHING_LIFETIME_CURRENT);

$my_cache_id = (int) $_GET['article_id'];

if (!$smarty->isCached('index.tpl', $my_cache_id)) {
    // ...
}

$smarty->display('index.tpl', $my_cache_id);

Clearing specific caches

You can clear all caches for a particular $cache_id by passing NULL as the first parameter to clearCache().

<?php
use Smarty\Smarty;
$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.

Advanced cache grouping

You can do more elaborate grouping by setting up $cache_id groups. This is accomplished by separating each sub-group with a vertical bar | in the $cache_id value. You can have as many sub-groups as you like.

• You can think of cache groups like a directory hierarchy. For instance, a cache group of 'a|b|c' could be thought of as the directory structure '/a/b/c/'.

• clearCache(null, 'a|b|c') would be like removing the files '/a/b/c/*'. clearCache(null, 'a|b') would be like removing the files '/a/b/*'.

• If you specify a template name such as clearCache('foo.tpl', 'a|b|c') then Smarty will attempt to remove '/a/b/c/foo.tpl'.

• You CANNOT remove a specified template name under multiple cache groups such as '/a/b/*/foo.tpl', the cache grouping works left-to-right ONLY. You will need to group your templates under a single cache group hierarchy to be able to clear them as a group.

Cache grouping should not be confused with your template directory hierarchy, the cache grouping has no knowledge of how your templates are structured. So for example, if you have a template structure like themes/blue/index.tpl and you want to be able to clear all the cache files for the "blue" theme, you will need to create a cache group structure that mimics your template file structure, such as display('themes/blue/index.tpl', 'themes|blue'), then clear them with clearCache(null, 'themes|blue').

<?php
use Smarty\Smarty;
$smarty = new Smarty;

$smarty->setCaching(Smarty::CACHING_LIFETIME_CURRENT);

// clear all caches with 'sports|basketball' as the first two cache_id groups
$smarty->clearCache(null, 'sports|basketball');

// clear all caches with "sports" as the first cache_id group. This would
// include "sports|basketball", or "sports|(anything)|(anything)|(anything)|..."
$smarty->clearCache(null, 'sports');

// clear the foo.tpl cache file with "sports|basketball" as the cache_id
$smarty->clearCache('foo.tpl', 'sports|basketball');

$smarty->display('index.tpl', 'sports|basketball');