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<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.19 $ -->
<!-- splitted from ./en/functions/var.xml, last change in rev 1.2 -->
<refentry id="function.unserialize">
<refnamediv>
<refname>unserialize</refname>
<refpurpose>
Creates a PHP value from a stored representation
</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<methodsynopsis>
<type>mixed</type><methodname>unserialize</methodname>
<methodparam><type>string</type><parameter>str</parameter></methodparam>
</methodsynopsis>
<simpara>
<function>unserialize</function> takes a single serialized
variable (see <function>serialize</function>) and converts it
back into a PHP value. The converted value is returned, and can
be a <type>boolean</type>, <type>integer</type>, <type>float</type>,
<type>string</type>, <type>array</type> or <type>object</type>.
In case the passed string is not unserializeable, &false; is returned and
<literal>E_NOTICE</literal> is issued.
</simpara>
<warning>
<para>
&false; is returned both in the case of an error and if unserializing
the serialized &false; value. It is possible to catch this special case by
comparing <parameter>str</parameter> with
<literal>serialize(false)</literal> or by catching the issued
<literal>E_NOTICE</literal>.
</para>
</warning>
<note>
<title>unserialize_callback_func directive</title>
<para>
It's possible to set a callback-function which will be called,
if an undefined class should be instantiated during unserializing.
(to prevent getting an incomplete <type>object</type> "__PHP_Incomplete_Class".)
Use your &php.ini;, <function>ini_set</function> or &htaccess;
to define 'unserialize_callback_func'. Everytime an undefined class
should be instantiated, it'll be called. To disable this feature just
empty this setting. Also note that the directive
unserialize_callback_func directive became
available in PHP 4.2.0.
</para>
</note>
<para>
If the variable being unserialized is an object, after successfully
reconstructing the object PHP will automatically attempt to call the
<function>__wakeup</function> member function (if it exists).
<example>
<title>unserialize_callback_func example</title>
<programlisting role="php">
<![CDATA[
<?php
$serialized_object='O:1:"a":1:{s:5:"value";s:3:"100";}';
// unserialize_callback_func directive available as of PHP 4.2.0
ini_set('unserialize_callback_func', 'mycallback'); // set your callback_function
function mycallback($classname)
{
// just include a file containing your classdefinition
// you get $classname to figure out which classdefinition is required
}
?>
]]>
</programlisting>
</example>
</para>
<note>
<para>
In PHP 3, methods are not preserved when unserializing a
serialized object. That limitation was removed in PHP 4 as both
properties and methods are now restored. Please see the <link
linkend="language.oop.serialization">Serializing Objects</link>
section of <link linkend="language.oop">Classes and
Objects</link> or more information.
</para>
</note>
<para>
<example>
<title><function>unserialize</function> example</title>
<programlisting role="php">
<![CDATA[
<?php
// Here, we use unserialize() to load session data to the
// $session_data array from the string selected from a database.
// This example complements the one described with serialize().
$conn = odbc_connect("webdb", "php", "chicken");
$stmt = odbc_prepare($conn, "SELECT data FROM sessions WHERE id = ?");
$sqldata = array ($PHP_AUTH_USER);
if (!odbc_execute($stmt, &$sqldata) || !odbc_fetch_into($stmt, &$tmp)) {
// if the execute or fetch fails, initialize to empty array
$session_data = array();
} else {
// we should now have the serialized data in $tmp[0].
$session_data = unserialize($tmp[0]);
if (!is_array($session_data)) {
// something went wrong, initialize to empty array
$session_data = array();
}
}
?>
]]>
</programlisting>
</example>
</para>
<para>
See also <function>serialize</function>.
</para>
</refsect1>
</refentry>
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