session classes and constructors

[Anon]

Hi there all!

I am having a problem with using classes with session. what i want to do is save an object onto the session which is no problem. the class of the object has a constructor and i am using this constructor on the page that i register the object on. the problem is that when i come back to this page later the constructor is being called again and i am losing the fields in the object. so my code is like this:

someClass.inc:

class someClass{
var $aField;
function someClass($mField){
$this->aField = $mField;
}
... rest of the class

}

aPage.php:

include("someClass.inc");
session_register("MyObject");
$MyObject = new someClass(10);

... rest of the page

if i change $MyObject->aField somewhere (maybe on this page) and then come back to this page, the object is re-initialised. i have tried this:

aPage.php:

include("someClass.inc");
if(!session_is_registered("MyObject")){
session_register("MyObject");
$MyObject = new someClass(10);
}

... rest of the page

but i get the error about trying to call a function that does not exist i.e. did not recognise or find the class.

Any help would be greatly appreciated. Thanks.

Ziad

[jsobell]

You are wiping over your session variable with a new object when you call
'$MyObject = new someClass(10);'
This is correct, and the problem lies in your storing and retrieving the object.
Simply stating 'global $MyObject' should (in theory) be enough to retrieve the original values of the object, but I must admit that I have never got the documented methods to work properly, and have always reverted to serializing the object and saving it in a session variable as a string, then deserializing it to get it back to an object.

Cheers,
Jason

[[deleted]]

Objects in sessions are very simple.

To put it into the session:
create the object.
register the object in the session.

To get it back from a session:
make sure the class definition for the object is available to the script (include file or raw code)
start the session
(do it in this order!)

You can use things like session_is_registered() to see if the var is in the session already.

[jsobell]

Ah, that would probably explain it.
I suspect I was always starting the session before including the class file, assuming that I could simply include the classes in the modules I wanted to use them in.

Thanks for that info!

Cheers,
Jason

[[deleted]]

Make sure you have

error_reporting(E_ALL)

at the top of your scripts. That fill report errors like those; telling you there is an incomplete class definition. (parts came from the session, the rest should have come from the script itself, thus incomplete)

[jsobell]

Excellent advice.

Thanks,
Jason