Allow only ajax request once (e.g. button)

Question

I have a button that, when clicked, adds 1 to the value of the table in my database (for example, to the button).

When the user clicks the button:

  var button_id = $(e.target).closest('div').attr('id');
  var id = button_id.substring(12);
  $.ajax({
    method: 'POST',
    url: 'update_like.php',
    data: {id:id},
    success: function(){
     //
    },
    error: function(){
      //
    }
  }) 

update_like.php

$id = mysqli_real_escape_string($conn,$_POST['id']);

if (!empty($_POST)){
    mysqli_query($conn,"UPDATE posts SET likes=likes+1 WHERE id='$id'");
}

Q: How can he check if you liked it so that they can only resemble a message once?

I just thought of something like this:

Enter a column called "likers" or something similar, with a long list of user IDs who liked the post.

i.e.

5 217 16 31893 ... User IDs

In update_like.php, check if the user who registered the identifier in this line is not found. Sort of:

$id = mysqli_real_escape_string($conn,$_POST['id']);

$result = mysqli_query($conn,"SELECT likers FROM posts WHERE id='$id'");
$likers = mysqli_fetch_assoc($result);
$user_id = $_SESSION['id']; // user ID

if (!empty($_POST)){
    if (!(preg_match("/\b$user_id\b/", $likers))){
        mysqli_query($conn,"UPDATE posts SET likes=likes+1 WHERE id='$id'");
    }
}

Is it possible?

Answer 1

You can try the following:

var button_id = $(e.target).closest('div').attr('id');
var id = button_id.substring(12);
var idArray = [];
if (idArray.indexOf(id) === -1) {
 ajaxCall = $.ajax({
    method: 'POST',
    url: 'update_like.php',
    data: {id:id},
    success: function(){
     //
      idArray.push(id);
    },
    error: function(){
      //
    }
  });
}

: , , .

UPDATE posts 
SET likes = likes+1 
WHERE id = '$id'
AND FIND_IN_SET('$id', listofuserid) = 0