Ajax POST call to PHP - php

Question

I'm trying to send a string from my JS file to my PHP file with an AJAX POST call and then insert that string into my Wordpress database.
I am able to send the string however I get this error message:
Notice: Undefined index: data in C:\Bitnami\wordpress-5.0.3-2\apps\wordpress\htdocs\wp-content\plugins\Kalkylator\templates\create.php on line 81
line 81 is: $data = $_POST['data'];
JS FILE
$(document).ready(function() {
var testingString = "hello people";
$.ajax({
url: "admin.php?page=jvformbuilder_create",
method: "POST",
data: { 'data': testingString },
success: function(result) {
console.log("result: " + result);
},
error: function(error) {
console.log("error: " + error);
}
});
});
PHP FILE
$data = $_POST['data'];
echo $data;
insertToDB($data);
function insertToDB($data)
{
$db = new mysqli('localhost', 'root', 'password', 'bitnami_wordpress');
if ($db->connect_errno > 0)
{
die('Unable to connect to database [' . $db->connect_error . ']');
}
// Attempt insert query to database.
$testing = "INSERT INTO wp_test (value) VALUES ('$data')";
mysqli_close($db);
}
Here is the file structure
I am currently working on my happypath hence why I don't validate the input to the database.
All help and tips are welcome, thanks in advance :D
Edit: I managed to solve the problem, it was like alot of people suggested that the data was being redirected in admin.php. so I just moved my php function there and now it works (atleast for my happypath). Thanks alot to all who took their time to help :D

Answer 1

You need to pass $data to the insertToDB() function. You currently reference it like this:
$data = $_POST['data'];
echo $data;
insertToDB ();
You need to do this:
$data = $_POST['data'];
echo $data;
insertToDB ($data);