PHP variable scope between php files

Question

I have a form which creates a shipment and stores it in my database. Upon success I want to print the tracking number and a QR Code based on the number. Unfortunately the scope of my variables can't reach the .php file I want. I have tried 2 things as you can see in the comments but in both attempts the scope seems to be the problem. Any ideas?

shipment.php code:

<?php 
include 'core/init.php';
include 'includes/overall/kat_start.php';

if (empty($_POST) === false)
{
    $required_fields = array('city', 'destination', 'time', 'cost', 'type');
    //echo '<pre>', print_r($_POST, true), '</pre>';
    $field_length = array('city', 'destination');

    foreach($_POST as $key=>$value)
    {
        if(empty($value) && in_array($key, $required_fields) === true)
        {
            $errors[] = 'Fields marked with an asterisk are required.';
            break 1;
        }
    }

    if(empty($errors) === true){
        foreach($_POST as $key=>$value){
            if(strlen($value) > 30 && in_array($key, $field_length) === 
true){
                $errors[]='The size of one of your entries is not 
acceptable. Entry size must be smaller than 30 characters.';
            }
        }

    }
}

?>
<h1>Create Shipment</h1>

<?php
if(isset($_GET['success']) && empty($_GET['success'])){
    echo 'You have created a shipment succesfully';
    //echo $register_data['trnumber'];
    //This doesn't work, I get "variable 'register_data' undefined error!
}
else
{
    if(empty($_POST) === false && empty($errors) === true)
    {
        $GLOBALS['trnumber'] = tracking_number($_POST['city'], 
$_POST['destination']);
        $register_data = array
        (
            'trnumber'     => $trnumber,
            'city'         => $_POST['city'],
            'destination'  => $_POST['destination'],
            'time'         => $_POST['time'],
            'cost'         => $_POST['cost'],
            'type'         => $_POST['type'],
        );
        shipment_submit($register_data);
        header('Location: qrcode.php');
    }
    else{echo output_errors($errors);}
?>
    <form action="" method="post">
    <ul>
        <li>
            Starting City*:<br>
            <input type="text" name="city">
        </li>
        <p><li>
            Destination*:<br>
            <input type="text" name="destination">
        </li></p>
        <p><li>
            Time*:<br>
            <input type="text" name="time">
        </li></p>
        <p><li>
            Cost*:<br>
            <input type="text" name="cost">
        </li></p>
        <p><li>
            Type*:<br>
            <input type="text" name="type">
        </li></p>
        <p><li>
            <input type="submit" value="Submit">
        </li></p>

    </ul>

</form>

<?php 
}
include 'includes/overall/end.php'; ?>

================ qrcode.php code:

<?php 
include 'core/init.php';
//logged_in_redirect();
include 'includes/overall/kat_start.php';
//include 'shipment.php';
//This include creates errors, it shouldnt be here
?>

<h2>You created the shipment successfully</h2>

<?php 
echo $GLOBALS['trnumber'];
//This doesn't work I get "undefined index 'trnumber'" error
?>

If these are two separate HTTP requests then anything in-memory will start anew in the second request. You could use something like $_SESSION to persist a value between requests. — David
– David, Commented May 20, 2017 at 16:58
When you use a header() redirect you are actually reloading the page. The reason you can't pass variables between the two is that they are in no way connected. To pass a variable through here you would need to add anything you want passed through into a query string on the end of your url and then get it from the _GET. You could also use a session and store things in _SESSION if you prefer. — D Lowther
– D Lowther, Commented May 20, 2017 at 17:00

MikeyT · Accepted Answer · 2017-05-20 16:59:55Z

2

One solution to your problem is using $_SESSION

<?php 
session_start();
/*session is started if you don't write this line can't use $_SESSION */
$_SESSION["trnumber"]=$value;

echo $_SESSION["trnumber"];
?>

answered May 20, 2017 at 16:59

MikeyT

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2 Comments

MikeyT Over a year ago

Yup, then you can use $_SESSION["trnumber"]; in all your other .php files. I would suggest making sure you unset that variable when it is no longer needed/required.

alex777 Over a year ago

Thanks for the suggestion!

Shawn Mehan · Accepted Answer · 2017-05-20 23:35:48Z

0

Instead of this

'trnumber'     => $trnumber,

Try With

'trnumber'     => $GLOBALS['trnumber'],

And in qrcode.php code access this as $trnumber

edited May 20, 2017 at 23:35

Shawn Mehan

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answered May 20, 2017 at 17:00

Vishnu

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2 Comments

alex777 Over a year ago

This idea does not work. I get undefined variable error.

Vishnu Over a year ago

Can you able to print value of $GLOBALS['trnumber'] before redirecting to qrcode.php?

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