Question

I’m trying to implement and authentication system with jQuery and PHP. All the php work is made in the controller and datahandler class. There is no php code inside the .html files, all the values in .html files are rendered via jQuery that request the data from php server. So what I’m trying to do is:

1. When user clicks the login button, the jQuery makes a call to the authenticate() method in my controller class, it checks if the user is correct and stuff, and if it is, start the session and set the user_id on the session so I can access it later, and returns the userId to the jQuery client again.
2. After that, if everything is fine, in jQuery I redirect it to the html file. On the html file I call a jQuery from the <script> tag that will handle other permissions. But this jQuery will access the method getPermissionString (from the same class of authenticate() method mentioned before), and it will need to get the session value set in authenticate method.

The Problem:

When I try to get the session value inside getPermissionString() it says:

Notice: Undefined variable: _SESSION

I’ve tried to check if the session is registered in the second method, but looks like it’s not. Here is my PHP code.

Any idea? Thanks.

public function authenticate($login, $password)
{
    $result = $this->userDataHandler->authenticateUser($login, $password);

    if(is_numeric($result) && $result != 0) 
    {
        session_start();
        $_SESSION["uid"] = $result;

        if(isset($_SESSION["uid"]))
        {
            echo "registered";
            $userId = $_SESSION["uid"]; 
        }
        else
        {
            echo "not registered";  
        }

        echo $result;
    }
    else
    {
        echo 0; 
    }
}

public function getPermissionString()
{
    if(isset($_SESSION["uid"]))
    {
        echo "registered";
        $userId = $_SESSION["uid"]; 
    }
    else
    {
        echo "not registered";  
    }
}

Answer 1

Before you can access $_SESSION in the second function you need to ensure that the program has called session_start() beforehand. The global variable is only populated when the session has been activated. If you never remember to start a session before using it then you can change the php.ini variable below:

[session]
session.auto_start = 1

Further, you said that you’re using a class for your code. In this case you can also autos tart your session each time the class in created by using magic methods:

class auth {
  function __construct() {
    session_start();
  }
  function yourfunction() {
    ...
  }
  function yoursecondfunction(){
    ...
  }
}