Controlling Cacheability of Output {#caching.cacheable}

If caching is enabled normally the whole final output of the page gets cached. However Smarty3 offers several options how to exclude sections of your output from caching.

> Note > > Be sure any variables used within a non-cached section are also > assigned from PHP when the page is loaded from the cache.

Cacheability of Template Section {#cacheability.sections}

A larger section of your template can easily excluded from caching by using the {nocache} and {/nocache} tags.

Today's date is
{nocache}
{$smarty.now|date_format}
{/nocache}

The above code will output the current date on a cached page.

Cacheability of Tags {#cacheability.tags}

Caching for an individual tag can be disabled by adding the \"nocache\" option flag to the tag.

Today's date is
{$smarty.now|date_format nocache}

Cacheability of Variables {#cacheability.variables}

You can assign() variables as not cachable. Any tag which uses such variable will be automatically executed in nocache mode.

> Note > > If a tag is executed in nocache mode you must make sure that all other > variables used by that tag are also assigned from PHP when the page is > loaded from the cache.

> Note > > The nocache status of an assigned variable will effect the compiled > template code. If you change the status you must manually delete > existing compiled and cached template files to force a recompile.

// assign $foo as nocahe variable
$smarty->assign('foo',time(),true);

Dynamic time value is {$foo}

Cacheability of Plugins {#cacheability.plugins}

The cacheability of plugins can be declared when registering them. The third parameter to registerPlugin() is called $cacheable and defaults to TRUE.

When registering a plugin with $cacheable=false the plugin is called everytime the page is displayed, even if the page comes from the cache. The plugin function behaves a little like an {insert} function.

> Note > > The $cacheable status will effect the compiled template code. If you > change the status you must manually delete existing compiled and > cached template files to force a recompile.

In contrast to {insert} the attributes to the plugins are not cached by default. They can be declared to be cached with the fourth parameter $cache_attrs. $cache_attrs is an array of attribute-names that should be cached, so the plugin-function get value as it was the time the page was written to cache everytime it is fetched from the cache.

<?php
$smarty->setCaching(Smarty::CACHING_LIFETIME_CURRENT);

function remaining_seconds($params, $smarty) {
    $remain = $params['endtime'] - time();
    if($remain >= 0){
        return $remain . ' second(s)';
    }else{
        return 'done';
    }
}

$smarty->registerPlugin('function','remaining', 'remaining_seconds', false, array('endtime'));

if (!$smarty->isCached('index.tpl')) {
    // fetch $obj from db and assign...
    $smarty->assignByRef('obj', $obj);
}

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

where index.tpl is:

Time Remaining: {remaining endtime=$obj->endtime}

The number of seconds till the endtime of $obj is reached changes on each display of the page, even if the page is cached. Since the endtime attribute is cached the object only has to be pulled from the database when page is written to the cache but not on subsequent requests of the page.

index.php:

<?php
$smarty->setCaching(Smarty::CACHING_LIFETIME_CURRENT);

function smarty_block_dynamic($param, $content, $smarty) {
    return $content;
}
$smarty->registerPlugin('block','dynamic', 'smarty_block_dynamic', false);

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

where index.tpl is:

Page created: {'0'|date_format:'%D %H:%M:%S'}

{dynamic}

Now is: {'0'|date_format:'%D %H:%M:%S'}

... do other stuff ...

{/dynamic}

When reloading the page you will notice that both dates differ. One is "dynamic" one is "static". You can do everything between {dynamic}...{/dynamic} and be sure it will not be cached like the rest of the page.

> Note > > The above example shall just demonstrate how a dynamic block plugins > works. See > Cacheability of Template Section on how to > disable caching of a template section by the built-in > {nocache} and > {/nocache} tags.