如何从进程文件发回数据？ （例如错误）

Question

I'm working on a login system, and I was wondering how to send errors back to the form?
I will personally use AJAX in my project so it won't really a problem but I'm curious to know how it's possible with pure php.

This is the form... On login.php or some other page:

<form method="post" action="proccessLogin.php">
    <label for="username">Username: </label>
    <input type="text" name="username" />
    <label for="password">Password: </label>
    <input type="password" name="password" />

    <input type="submit" name="submit" value="Go!" />
</form>

processLogin.php:

<?php
    $username = $_POST['username'];
    $password = $_POST['password'];

    if(password is incorrect){
        // send error or add to an error array and then send it.
    }

    etc...
?>

This is just a piece of code I just wrote so it's obviously not complete.

Thank you!

Answer 1

use session to set the errors.. refer below modified code..

login.php

<?php
session_start();
?>
<form method="post" action="proccessLogin.php">
    <label for="username">Username: </label>
    <input type="text" name="username" />
    <?php if($_SESSION['u_name_error']) { echo $_SESSION['u_name_error']; unset($_SESSION['u_name_error']); }
    <label for="password">Password: </label>
    <input type="password" name="password" />
    <?php if($_SESSION['pass_error']) { echo $_SESSION['pass_error']; unset($_SESSION['pass_error']); }
    <input type="submit" name="submit" value="Go!" />
</form>

==============
proccessLogin.php
<?php
session_start();

    $username = $_POST['username'];
    $password = $_POST['password'];

    if(password is incorrect){
        // send error or add to an error array and then send it.
    }else{

        //set errors in session..
        $_SESSION['pass_error']= 'error message';
        $_SESSION['u_name_error']= 'error message';
        header("Location: login.php");
        die;
    }

?>