PHP value not being caught by AJAX - php

Question

I have some code that sends a variable (pin) to php via AJAX the database is then queried and if a result is found the php echo's a value of 1. Everything is working fine, except that the Ajax does not recognise the value returned by the php.
Here is my code
$(document).ready(function () {
$("form.submit").submit(function () {
var pin = $(this).find("[name='pin']").val();
// ...
$.ajax({
type: "POST",
url: "http://www.example.com/pin.php",
data: {
pin : pin,
},
success: function (response) {
if (response == "1") {
$("#responsecontainer").html(response);
window.location.href = "home.html?user=" + user;
// Functions
} else { // Login failed
alert("LOGIN FAILED");
}
}
});
this.reset();
return false;
});
});
And here is my PHP code, I know that the code below returns a value of 1. When Ajax is triggered it returns a value that generates a login fail message. Is there a way to see what Ajax is sending, if i swap out the ajax and directly submit the for to the server it also returns a 1 on the php echo.
$pin = $_GET["pin"];
$db = new PDO("mysql:host=localhost;dbname=xxxxx;charset=utf8", "xxxx", "xxxx");
$count = $db->query("SELECT count(1) FROM users WHERE pin='$pin'")->fetchColumn();
echo $count;

Answer 1

It's recommended to return JSON data as result for an ajax request.
So try this :
Edit: I've updated the php code to make the sql query with PDO prepare() method taking into account #Dominik's commentary
$pin = $_POST['pin'];
$db = new PDO('mysql:host=localhost;dbname=xxxxx;charset=utf8', 'xxxx', 'xxxx');
$stmt = $pdo->prepare('SELECT count(1) FROM users WHERE pin = :pin');
$stmt->execute(array('pin' => $pin));
return json_encode([
"count" => $stmt->fetchColumn()
]);
And in your ajax success callback :
...
success: function(response) {
var count = JSON.parse(response).count;
if (count == "1") {
$("#responsecontainer").html(response);
window.location.href = "home.html?user="+ user;
} else {// Login failed
alert("LOGIN FAILED");
}
},
error: function(error) {
...
}
Hope it's helps you :)