如何检查会话中的变量是否被声明？ [重复]

Question

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• CodeIgniter-Checking session variable is already set or not when clicking each link or reloading page 3 answers

I am trying to figure something out. I am using CodeIgniter and I am storing some information in the session so I can access it everywhere. I need to check if a variable has been already set, but the code I am using is not working (controller break apart)

This is how I store the data in the session:

$this->session->set_userdata('myvalue', 'x');

And this is how I am trying to check if the variable has been declared:

if (isset($this->session->userdata('myvalue'))) //doesn't work

In advance thanks for reading and replying ;)

BTW: I need this function, because if I know that the var hasn't been declared it means the session has expired and has been destroyed. So I want to forward the user to a view where I tell him he has been inactive for too long and has been automatically logged out, etc.

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Answer 1

This is how to check if a specific value is set in CodeIgniter's sessions:

if ( $this->session->userdata('myvalue') ) {
    // The item 'myvalue' exists in the session
} else {
    // The item 'myvalue' does not exist in the session
}

---

This is how CodeIgniter's userdata() function works, in system/libraries/Session.php:

function userdata($item)
{
    return (!isset($this->userdata[$item])) ? FALSE : $this->userdata[$item];
}

If the item doesn't exist in the session, FALSE is returned, otherwise the item is.