PHP in a Nutshell

Storing Complex Data Types

You can use sessions to store complex data types such as objects and arrays simply by treating them as standard variables, as this code shows:

    $myarr["0"] = "Sunday";
    $myarr["1"] = "Monday";
    $myarr["2"] = "Tuesday";
    $myarr["3"] = "Wednesday";
    $myarr["4"] = "Thursday";
    $myarr["5"] = "Friday";
    $myarr["6"] = "Saturday";

    $_SESSION["myarr"] = $myarr;

You can also use the serialize() and unserialize() functions to explicitly convert to and from a string. If you do not call serialize() yourself, PHP will do it for you when the session data is written to disk—many do rely on this, but I would say it's best to be explicit and serialize() data yourself.

If you are trying to store objects in your session and you find it is not restoring the class name properly, it is probably because you started the session before you had the class defined. This problem is often encountered by people who use the session.auto_start directive in php.ini.