Zoho Sign Webhook – Receiving Response Using PHP

I’m creating a script that will receive response from Zoho Sign Webhook. I use the following condition to trigger the Webhook :

I am able to receive the hit into the Callback URL by saving every response into the database. I’m using a simple code below :

<?php 

$data = file_get_contents('php://input');
$escape = mysqli_real_escape_string($conn, $data);

$q=mysqli_query($conn,"INSERT INTO `response` VALUES ('','$escape')");
if($q){
    echo "success";
}else{
    echo "failed - ".mysqli_error($conn);
}

?>

But i always get empty response using the script above. The $data, $post, or $get variable is always empty.

I tried to find the documentation on the Zoho and other question on stackoverflow but i only can get this discussion here and here. Which is not solving my problem.

Any other way to get the response from Zoho Sign Webhook using PHP?

Answer

Thanks @CBroe for the explanation, the problem with my callback was because of missing trailing slash on my callback URL:

http://sub.domain.com/callback

and the problem solved when i change it into :

http://sub.domain.com/callback/