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Cache Handler Function

As an alternative to using the default file-based caching mechanism, you can specify a custom cache handling function that will be used to read, write and clear cached files.

Create a function in your application that Smarty will use as a cache handler. Set the name of it in the $cache_handler_func class variable. Smarty will now use this to handle cached data.

  • The first argument is the action, which will be one of read, write and clear.

  • The second parameter is the Smarty object.

  • The third parameter is the cached content. Upon a write, Smarty passes the cached content in these parameters. Upon a read, Smarty expects your function to accept this parameter by reference and populate it with the cached data. Upon a clear, pass a dummy variable here since it is not used.

  • The fourth parameter is the name of the template file, needed for read/write.

  • The fifth parameter is the optional $cache_id.

  • The sixth is the optional $compile_id.

  • The seventh and last parameter $exp_time was added in Smarty-2.6.0.

Example 15.5. Example using MySQL as a cache source

example usage:


$smarty = new Smarty;
$smarty->cache_handler_func = 'mysql_cache_handler';


mysql database is expected in this format:

create database SMARTY_CACHE;

create table CACHE_PAGES(
CacheID char(32) PRIMARY KEY,


function mysql_cache_handler($action, &$smarty_obj, &$cache_content, $tpl_file=null, $cache_id=null, $compile_id=null, $exp_time=null)
	// set db host, user and pass here
	$db_host = 'localhost';
	$db_user = 'myuser';
	$db_pass = 'mypass';
	$db_name = 'SMARTY_CACHE';
	$use_gzip = false;

	// create unique cache id
	$CacheID = md5($tpl_file.$cache_id.$compile_id);

	if(! $link = mysql_pconnect($db_host, $db_user, $db_pass)) {
		$smarty_obj->_trigger_error_msg('cache_handler: could not connect to database');
		return false;

	switch ($action) {
		case 'read':
			// read cache from database
			$results = mysql_query("select CacheContents from CACHE_PAGES where CacheID='$CacheID'");
			if(!$results) {
				$smarty_obj->_trigger_error_msg('cache_handler: query failed.');
			$row = mysql_fetch_array($results,MYSQL_ASSOC);

			if($use_gzip && function_exists('gzuncompress')) {
				$cache_content = gzuncompress($row['CacheContents']);
			} else {
				$cache_content = $row['CacheContents'];
			$return = $results;
		case 'write':
			// save cache to database

			if($use_gzip && function_exists("gzcompress")) {
				// compress the contents for storage efficiency
				$contents = gzcompress($cache_content);
			} else {
				$contents = $cache_content;
			$results = mysql_query("replace into CACHE_PAGES values(
			if(!$results) {
				$smarty_obj->_trigger_error_msg('cache_handler: query failed.');
			$return = $results;
		case 'clear':
			// clear cache info
			if(empty($cache_id) && empty($compile_id) && empty($tpl_file)) {
				// clear them all
				$results = mysql_query('delete from CACHE_PAGES');
			} else {
				$results = mysql_query("delete from CACHE_PAGES where CacheID='$CacheID'");
			if(!$results) {
				$smarty_obj->_trigger_error_msg('cache_handler: query failed.');
			$return = $results;
			// error, unknown action
			$smarty_obj->_trigger_error_msg("cache_handler: unknown action \"$action\"");
			$return = false;
	return $return;



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