Files
smarty/docs/en/programmers/api-functions/api-is-cached.xml
messju de676ea589 added $compile_id parameter
and a note about is_cached's internals
2004-07-02 08:33:32 +00:00

106 lines
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XML

<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision$ -->
<refentry id="api.is.cached">
<refnamediv>
<refname>is_cached</refname>
<refpurpose></refpurpose>
</refnamediv>
<refsect1>
<title />
<methodsynopsis>
<type>bool</type><methodname>is_cached</methodname>
<methodparam><type>string</type><parameter>template</parameter></methodparam>
<methodparam choice="opt"><type>string</type><parameter>cache_id</parameter></methodparam>
<methodparam choice="opt"><type>string</type><parameter>compile_id</parameter></methodparam>
</methodsynopsis>
<para>
This returns &true; if there is a valid cache for this template.
This only works if <link
linkend="variable.caching">caching</link> is set to true.
</para>
<example>
<title>is_cached</title>
<programlisting role="php">
<![CDATA[
<?php
$smarty->caching = true;
if(!$smarty->is_cached("index.tpl")) {
// do database calls, assign vars here
}
$smarty->display("index.tpl");
?>
]]>
</programlisting>
</example>
<para>
You can also pass a cache id as an optional second parameter
in case you want multiple caches for the given template.
</para>
<para>
You can supply a compile id as an optional third parameter.
If you omit that parameter the persistent
<link linkend="variable.compile.id">$compile_id</link> is used.
</para>
<para>
If you do not want to pass a cache id but want to pass a compile
id you have to pass <literal>null</literal> as cache id.
</para>
<example>
<title>is_cached with multiple-cache template</title>
<programlisting role="php">
<![CDATA[
<?php
$smarty->caching = true;
if(!$smarty->is_cached("index.tpl", "FrontPage")) {
// do database calls, assign vars here
}
$smarty->display("index.tpl", "FrontPage");
?>
]]>
</programlisting>
</example>
<note>
<title>Technical Note</title>
<para>
If <literal>is_cached</literal> returns true it actually loads the
cached output and stores it internally. Any subsequent call to
<link linkend="api.display">display()</link> or
<link linkend="api.fetch">fetch()</link>
will return this internally stored output and does not try to reload
the cache file. This prevents a race condition that may occur when a
second process clears the cache between the calls to is_cached and to
display in the example above. This also means calls to
<link linkend="api.clear.cache">clear_cache()</link>
and other changes of the cache-settings may have no effect after
<literal>is_cached</literal> returned true.
</para>
</note>
</refsect1>
</refentry>
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