Question

I am having problem with implementing custom session handler in php.
The code:
http://pastebin.com/9QV9f22Q

I initialize this once in my frameworks bootstrap, after I have connection with db:

require_once 'DbSession.php';
$session = new DbSession();
session_start();

But then I can’t view my page. Firefox gets 302 Status with “Server not found” error. Firebug says that content is 5k long, but I can’t view the page.

Log after one reload:
http://pastebin.com/JYe14nGR

I wonder why it still “loses” that created DbSession instance. Do yo have any ideas? TIA

Answer 1

Your code is based on a false premise: that you can return a different object from a PHP constructor. Quite the opposite: PHP entirely ignores the return value from a constructor.

Here’s what’s actually happening.

When your code calls:

$session = new DbSession();

the $firstTime == false check runs, meaning getInstance() gets called.

getInstance finds no existing instance, so it calls setup().

setup() calls new DbSession() again, this time passing in the argument preventing another call to getInstance(). It creates the object, registers it as the session handler, and returns it.

getInstance shoves the object in a static variable, and then returns it to the original constructor call. The original constructor call then drops the existing object on the ground and returns a brand new copy of itself.

You can fix some of this insanity by never instantiating the object outside of setup/getInstance(). Try making the constructor protected and only ever calling getInstance().

However, none of this explains why the code is malfunctioning for you. In fact, we can’t explain it either. We’re missing all the rest of the code, including what database adapter you’re using, what ORM you’re using (or even if you are using an ORM, your class and method names suggest it), what framework(s) might be involved, etc.

Try cutting all of the actual database touching from the class. Just write files on disk. Get that working first, then introduce the database layer. Chances are that your error will become obvious at that point.