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Php versions – Cannot access html form data in a post message (PHP)

I am trying out a php sample code given here: https://www.tutorialrepublic.com/php-tutorial/php-mysql-login-system.php

This gives a log in form, where you can register username password and then log in with a registered user. A welcome page is only visible after you have logged in, and the welcome page shows the specific username of the currently logged in account.

I am trying to modify the welcome.php given in the above link, to add a data entry form that will save some personal data like name and age to a mariadb database. Here is my version of the welcome.php file:

<?php
// Initialize the session
session_start();
 
// Check if the user is logged in, if not then redirect him to login page
if(!isset($_SESSION["loggedin"]) || $_SESSION["loggedin"] !== true){
    header("location: login.php");
    exit;
}

$uname=htmlspecialchars($_SESSION["username"]);
$name = "";
$age = 0;

if($_SERVER["REQUEST_METHOD"] == "POST"){
    // /*
    echo '<script language="javascript">';
    echo 'alert("submit button clicked")';
    echo '</script>';
    // */
    // /*
    $tempvar = trim($_POST["name"]);
    // $tempvar='sdsd';
    var_dump($tempvar);
    if($tempvar == "")
        echo $tempvar.' found';
    // */
}

?>

 
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Welcome</title>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.css">
    <style type="text/css">
        body{ font: 14px sans-serif; text-align: center; }
    </style>
</head>
<body>
    <div class="page-header">
        <h1>Hi, <b><?php echo htmlspecialchars($_SESSION["username"]); ?></b>. Welcome to our site.</h1>
    </div>
    <p>
        <a href="reset-password.php" class="btn btn-warning">Reset Your Password</a>
        <a href="logout.php" class="btn btn-danger">Sign Out of Your Account</a>
    </p>
    <p>Enter your data here:</p>
    <!-- <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post"> -->
    <form action="<?php echo $_SERVER["PHP_SELF"]; ?>" method="post">
        Name: <input type="text" name="name"><br>
        Age: <input type="text" name="age"><br>
        <input type="submit" name="save" value="submit">
        <!-- <input type="submit" class="btn btn-primary" value="submit"> -->
    </form>
    
</body>
</html>

If I understand this correctly clicking the submit button should generate a post message which should be captured by the php script at the beginning of the file. This much is happening, but I cannot display the content of the text box given by <input type="text" name="name">. The var_dump($tempvar); in the php code at the beginning comes up with String(0) "". I have tried moving the php code to a separate file (as given here in insert.php) instead of attempting to process the post message in the same file, but I am getting the same result. I am not getting any errors.

How do I access the contents of the text box in the post message handler? I am testing this in XAMPP on Windows 10.

Tags:

3

Answers


  1. 0

    Your code works fine for me. I ran it in my system, it shows the submitted name with the var_dump i.e. string(18) "Md Shabbir Hossain".

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  2. 0

    Did the example with the login work correctly? This would prove that POSTing data works.

    Which version of PHP are you using? There was a feature called register_globals up to 5.4.0 which allowed accessing POST data via named variables. Since you are setting $name = "" this could overwrite your data. I would take it out at that position anyway (use an else clause if necessary). If you have register_globals active either update PHP or turn it off to avoid confusion.

    The next step to debug the issue is to print the whole array of $_POST like mentioned here but more pretty

    if($_SERVER["REQUEST_METHOD"] == "POST"){
    echo '<pre>';
    print_r($_POST);
    echo '</pre>';
    die();

    This will show you what values were actually POSTed.

    Same can be done with the $_SERVER array like this

    echo '<pre>';
print_r($_SERVER);
echo '</pre>';
die();
$uname=htmlspecialchars($_SESSION["username"]);

    The die() command will halt execution so you need to remove it when you want the script to continue.

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  3. 0

    There are some flaws that I would fix.

    Initial user get to Welcome.php.

    <?php
// Initialize the session
session_start();
 

// Check if the user is logged in, if not then redirect him to login page
if(!isset($_SESSION["loggedin"]) || $_SESSION["loggedin"] !== true){
    header("location: login.php");
    exit;
}

$uname=htmlspecialchars($_SESSION["username"]); //username is not defined or it does not exists yet.
$name = "";
$age = 0;

if($_SERVER["REQUEST_METHOD"] == "POST"){
    // /*
    echo '<script language="javascript">';
    echo 'alert("submit button clicked")';
    echo '</script>';
    // */
    // /*
    $tempvar = trim($_POST["name"]);
    // $tempvar='sdsd';
    var_dump($tempvar);
    if($tempvar == "")
        echo $tempvar.' found';
    // */
}

    I would do this:

    <?php
// Initialize the session
session_start();
 //Check if the user already logged.
if(!isset($_SESSION["loggedin"])){
    //Redirect
    header("location: login.php");
    exit;
}

// Check if post to login is submitted
if(isset($_POST['save'])){
  // /*
    echo '<script language="javascript">';
    echo 'alert("submit button clicked")';
    echo '</script>';
  $uname = '';
  //Check if Username is submitted
  if(isset($_POST['username'])){
     $_SESSION["username"] = $_POST['username'];
     $uname=htmlspecialchars($_SESSION["username"]);
  }
  $name = "";
  $age = 0;
  

  //For test
  var_dump($_POST[]);
}
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