John Davidson

Message:

I am submitting a POST request via AJAX to my PHP script. The browser tools Network tab shows the POST data has values, on arrival at my PHP script the $_POST value is true, isset() verification is valid, and there should be no problem to assign the $_POST['input'] values to my $variables.

Yet, my debug bar tells me that the PHP variables like $first_name are infact empty. I am feeling very stupid here, what am I missing?

AJAX

$('#newUserSubmit').click(function() {

    console.log('Submit button clicked.');



    if ($('#addNewUser').valid()) {

        console.log('Form on submit is valid');



        $.ajax({

            type: 'POST',

            url: '../../controllers/admin_addNewUser.php',

            data: {

                action: 'add_new_user',

                user_data: $('#addNewUser').serialize()

            },

            cache: false,

            success: function(data) {

                alert(data);

                console.log('Ajax POST request successful.');

            },

            error: function(xhr, status, error) {

                console.log('Ajax POST request failed.');

                console.error(xhr);

            }

        });



    } else {

        console.log('Form on submit is invalid');

        return false;

    }

});

Browser Network Tab:

Request Data

MIME Type: application/x-www-form-urlencoded; charset=UTF-8

action: add_new_user

user_data: first_name=John&last_name=Doe

PHP

if ($_SERVER['REQUEST_METHOD'] === 'POST') {

    $debug_msg = 'POST check: passed<br>';



    if (isset($_POST['action']) && ($_POST['action'] == 'add_new_user')) {

        $debug_msg .= 'ISSET check: passed<br>';



        // sanitize

        $fn = mysqli_real_escape_string($db, $_POST['first_name']);

        $ln = mysqli_real_escape_string($db, $_POST['last_name']);



    }

}

Response:

<b>Notice</b>:  Undefined index: first_name in <b>/path/to/script/admin_addNewUser.php</b> on line <b>27</b><br />

<br />

<b>Notice</b>:  Undefined index: last_name in <b>/path/to/script/admin_addNewUser.php</b> on line <b>28</b><br />

Appreciate any help on this, been staring at this for too long already.
Thanks

---

My Answer:
In your AJAX request, you are serializing the form data using $('#addNewUser').serialize(), which creates a URL-encoded string of form data. This means that the data sent to the server will be in the format of key-value pairs, like "first_name=John&last_name=Doe".

However, in your PHP script, you are trying to access $_POST['first_name'] and $_POST['last_name'], which do not exist in the serialized data. Instead, you should access the values using the keys 'first_name' and 'last_name' in the 'user_data' array.

Here's how you can modify your PHP script to access the values correctly:

php
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
$debug_msg = 'POST check: passed
';

if (isset($_POST['action']) && ($_POST['action'] == 'add_new_user')) {
$debug_msg .= 'ISSET check: passed
';

parse_str($_POST['user_data'], $userData);

// sanitize
$fn = mysqli_real_escape_string($db, $userData['first_name']);
$ln = mysqli_real_escape_string($db, $userData['last_name']);

}
}


By using parse_str($_POST['user_data'], $userData), you can convert the URL-encoded string into an associative array, allowing you to access the values using the correct keys.

This should solve the issue of empty POST values in your PHP script.