What is the proper way to test CodeIgniter session variable?

问题

Take the following code snippet. What is the best way to test to make sure the session variable isn't empty?

<?php if ($this->session->userdata('userID')) {
   $loggedIn = 1;
}
else {
   $loggedIn = 0;
} ?>

If later in my script, I call the following, the first prints properly, but on the second I receive Message: Undefined variable: loggedIn

<?php echo $this->session->userdata('userID'));
      echo $loggedIn; ?>

I've tried using !empty and isset, but both have been unsuccessful. I also tried doing the if/then statement backwards using if (!($this->session->userdata('userID')), but no dice. Any thoughts?

回答1:

Try doing the following instead:

<?php 
$loggedIn = 0;
if ($this->session->userdata('userID') !== FALSE) {
   $loggedIn = 1;
}
?>

If the error continues, you'll need to post more code in case you're calling that variable in another scope.

回答2:

If your aim is to see whether or not the session variable 'userID' is set, then the following should work:

$this->session->userdata('userID') !== false

回答3:

Why don't you create a boolean field in your session called is_logged_in and then check like:

if(false !== $this->session->userdata('is_logged_in'))

回答4:

if($this->session->userdata('is_logged_in')) {
    //then condition
}

This is the proper way to test!

来源：https://stackoverflow.com/questions/10712250/what-is-the-proper-way-to-test-codeigniter-session-variable