注册失败，登录等错误消息 - 使用$ GLOBAL oder $ _SESSION？

Question

For example: If anyone fails at the login function (for example: enters wrong password) on my webpage, i want to show an error-message at the webpage. My idea was like that:

    if(doLogin()) {
        //....
    }else {
        $GLOBAL['errorLogin'] = "Wrong Userdata";
    }

and then echo the global-variable in the .html.

But i searched also for this topic and found only this method, but everyone had used the $_SESSION variable for this instead of $GLOBAL.

Is my variant with the $GLOBAL varible wrong or bad practise? And why use $_SESSION for a error-message, if i only echo the message one time and don't need it in the next request?

Answer 1

I think you mean $GLOBALS (notice the s) which is a suber global variable and therefore can be accessed from anywhere in the PHP script (also from within functions or methods). There is nothing wrong about that.

I don't think that you should use the $_SESSION variable for that, because the user needs to see the error message only one time. In your case, and in most cases, that's why it might make no sense to store it in a session.

Personally, I just would use a custom errorMessage-Array, like that:

//store all Error Messages in one array.
$errorMessages = array();

if(doLogin()) {
    //....
}else {
    $errorMessages["Login"] = "Wrong Userdata";
}
//...
foreach($errorMessages as $key=>$message){
   echo $key.": ".$message."<br>";
}