Undefined index (key) in php error

Question

First, here are the hierarchy of files:

system/
...index.php
...core/
.......MasterView.php
.......Test.php
...sources/
.......ajax/
............ajaxtest.php
.......js/
............jstest.js
and so on.

index.php includes Test.php.

Test.php contains these lines:

$GLOBALS['foo'] = 'foo'; // note 1
require(ROOT.'/core/MasterView.php'); // render master view.

MasterView.php contains simple html tags but calls on jstest.js in system/sources/js/ directory.

jstest.js in system/sources/js/ directory made an ajax call to ajaxtest.php.

ajaxtest.php in system/sources/ajax/ directory contains this line:

echo $GLOBALS['foo']; // note 2

After running index.php on browser, the following error occurs:

Undefined index: foo in ...ajax\ajaxtest.php ...

particularly pointing to note 2 line. My question is, why does php does not recognize foo index when I have defined it on note 1 line before calling MasterView.php?

PS: I know the above method is not the best way to do it but I only give it as an illustration to my problem.

EDIT:

I've tried using $_SESSION['foo'] instead of $GLOBALS['foo'] in both files just to mention one solution I've tried. Same error occurs. Php does not recognize the index foo.

hakre · Accepted Answer · 2011-12-23 17:48:04Z

4

jstest.js in system/sources/js/ directory made an ajax call to ajaxtest.php.

Global variables are global to the same request only. If you connect files with an AJAX request in between, the global variable is not available because AJAX will create a new request.

You can share data across multiple requests by creating some sort of Server Session State by using cookies, a database or PHP sessions^Docs.

answered Dec 23, 2011 at 17:48

hakre

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5 Comments

dirkbonhomme Over a year ago

Spot on. A possible solution would be to store the data in $_SESSION. Look up the documentation for session handling in PHP

hakre Over a year ago

Session needs configuration and has pre-conditions. Actually they will work in your case however, you need to ensure that the client is using the appropriate session identifier with each request. Add the session id to your ajax request.

Shiplu Mokaddim Over a year ago

@NeigylR.Noval $_SESSION and $GLOBALS are not interchangeable.

Neigyl R. Noval Over a year ago

See edit. Sessions does not work either. Php still cannot determine the index 'foo'.

hakre Over a year ago

If you already have set that session value in the original request, but you can't obtain it in a later request, then your session is broken. You need to fix it first. It might just be that changing the variable name in two places is not enough. Please see the link to sessions PHP manual in the answer. Ensure that you pass the session id with your AJAX request: php.net/manual/en/session.idpassing.php

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