Setting Up Caching

The first thing to do is enable caching. This is done by setting $caching = true (or 1.)

require('Smarty.class.php');
$smarty = new Smarty;

$smarty->caching = true;

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

With caching enabled, the function call to display('index.tpl') will render the template as usual, but also saves a copy of its output to a file (a cached copy) in the $cache_dir. Upon the next call to display('index.tpl'), the cached copy will be used instead of rendering the template again.

Each cached page has a limited lifetime determined by $cache_lifetime. The default value is 3600 seconds, or 1 hour. After that time expires, the cache is regenerated. It is possible to give individual caches their own expiration time by setting $caching = 2. See the documentation on $cache_lifetime for details.

require('Smarty.class.php');
$smarty = new Smarty;

$smarty->caching = 2; // lifetime is per cache

// set the cache_lifetime for index.tpl to 15 minutes
$smarty->cache_lifetime = 300;
$smarty->display('index.tpl');

// set the cache_lifetime for home.tpl to 1 hour
$smarty->cache_lifetime = 3600;
$smarty->display('home.tpl');

// NOTE: the following $cache_lifetime setting will not work when $caching = 2.
// The cache lifetime for home.tpl has already been set
// to 1 hour, and will no longer respect the value of $cache_lifetime.
// The home.tpl cache will still expire after 1 hour.
$smarty->cache_lifetime = 30; // 30 seconds
$smarty->display('home.tpl');

If $compile_check is enabled, every template file and config file that is involved with the cache file is checked for modification. If any of the files have been modified since the cache was generated, the cache is immediately regenerated. This is a slight overhead so for optimum performance, leave $compile_check set to false.

require('Smarty.class.php');
$smarty = new Smarty;

$smarty->caching = true;
$smarty->compile_check = true;

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

If $force_compile is enabled, the cache files will always be regenerated. This effectively turns off caching. $force_compile is usually for debugging purposes only, a more efficient way of disabling caching is to set $caching = false (or 0.)

The is_cached() function can be used to test if a template has a valid cache or not. If you have a cached template that requires something like a database fetch, you can use this to skip that process.

require('Smarty.class.php');
$smarty = new Smarty;

$smarty->caching = true;

if(!$smarty->is_cached('index.tpl')) {
	// No cache available, do variable assignments here.
	$contents = get_database_contents();
	$smarty->assign($contents);
}

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

You can keep parts of a page dynamic with the insert template function. Let's say the whole page can be cached except for a banner that is displayed down the right side of the page. By using an insert function for the banner, you can keep this element dynamic within the cached content. See the documentation on insert for details and examples.

You can clear all the cache files with the clear_all_cache() function, or individual cache files (or groups) with the clear_cache() function.

require('Smarty.class.php');
$smarty = new Smarty;

$smarty->caching = true;

// clear out all cache files
$smarty->clear_all_cache();

// clear only cache for index.tpl
$smarty->clear_cache('index.tpl');

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