Having trouble posting jquery onto php - php

Question

I'm currently having some trouble posting a variable on jQuery for MySQLi SELECT on a PHP page.
Code of jQuery:
$("#carta1").click(function()
{
cartaId = document.getElementById("carta1").value;
console.log(cartaId);
ajaxGetResults = $.ajax({
context: this,
type: "POST",
url: "darResposta.php",
data: {'cartaId' : cartaId},
cache: false,
dataType: "json"
})
.done(function(data){
$('#3').html(data);
console.log("Avançou para a terceira parte");
$("#2").hide();
$("#3").show();
})
.fail(function(){
console.log('Erro ao buscar dados');
$("#2").hide();
$("#3").show();
$('#3').html("Deu erro");
});
});
Code of PHP:
if(!$conn)
{
echo "Falhou a ligação à base de dados";
}
else
{
if(isset($_POST['cartaId']))
{
$cartaId = $_POST['cartaId'];
$res = mysqli_query($conn,"
SELECT cartaNome, cartaDescricao
FROM tarot_cartas
WHERE cartaId = ".$cartaId
);
$data = array();
while($row = mysqli_fetch_assoc($res))
{
$data=$row;
}
echo json_encode($data);
}
}
Tried several approaches to this problem such as putting the $cartaId outside the if statement with a direct $_POST, and nothing happened.
Would appreciate if you could shed some light on this problem.
Thanks for taking the time to read and suggest a solution.

Answer 1

use below code
data: { 'cartaId' : cartaId },
instead of
data: {"data":JSON.stringify({'cartaId' : JSON.stringify(this)})},

Answer 2

Solution:
1.Remove this
data: {"data":JSON.stringify({'cartaId' : JSON.stringify(this)})},
2.Replace This one
data: { cartaId: cartaId }
Hope it works....

Answer 3

The jq you have will post a variable to the url.
To debug you should first check in a console (i use firebug) for mozilla) if the request is sent. Using firebug you can see the names of the POST variables you send.
Following this you should check what values get received on the server side by doing
var_dump($_POST);
Finally get the correct variable into your query. You can also debug the query by viewing the log file or, depending on whether you are using a framework, something like CI:
db->last_query();