PHP and JQuery Button trigger not working - php

Question

Im currently new to PHP and JQuery after having using ASP.Net and C Sharp for the 2 years. I have this major problem in which i require some assistance in.
I have a HTML <input type="submit" id="btnWL" value="Add to Wishlist"> button. Basically when this button is pressed a table called 'wishlist' in the database is checked to see if the current product is already in a wishlist. If no the button will trigger a database save else it will return a JQuery alert pop up error message.
I having difficulty in passing 2 PHP variables: $_SESSION["username"] and $_GET["ProductId"] into this JQuery method:
<script type="text/javascript">
$(document).ready(function() {
$('#btnWL').live('click', function() {
$.post("addToWishlist.php");
});
});
</script>
As you can see this JQuery method must pass those values to an external PHP File which checks for an already exsisting record in the 'wishist' table with those details.
<?php
$WishlistDAL = new WishlistDAL();
$result = $WishlistDAL->get_ProductInWishlistById($_GET["ProductId"]);
if (isset($_POST["isPostBack"])) {
if (isset($_SESSION["username"])) {
if (isset($_GET["btnWL"])) {
//Check if ProductId is in Cart
if (mssql_num_rows($result)>0)
{
//Return an error
//Sumhow this has to trigger an alert box in the above JQuery method
}
else
{
//Write in Wishlist Table
$WishlistDAL->insert_ProductInWishlist($_GET["ProductId"], $_SESSION["username"]);
}
}
}
else
{
//Return Error
}
}
?>
Another problem I have is then displaying an alert box using the same JQuery method for any errors that where generated in the php file.
Any Ideas how I can implement this logic? Thanks in advance.

Answer 1

Your "$.post()" call isn't passing any parameters, and has no callback for interpreting the results:
$.post('addToWishlist.php', { username: something, password: something }, function (response) {
});
The "something" and "something" would probably come from your input fields, so:
$.post('addToWishlist.php', { username: $('#username').val(), password: $('#password').val() }, function (response) {
});
Now the callback function would interpret the response from the server:
$.post('addToWishlist.php', { username: $('#username').val(), password: $('#password').val() }, function (response) {
if (response === "FAIL") {
alert("fail");
}
else {
// ... whatever ...
}
});
Exactly what that does depends on your server code; that "FAIL" response is something I just made up as an example of course.

Answer 2

jQuery accepts an callback:
$(document).ready(function() {
$('#btnWL').live('click', function() {
$.post("addToWishlist.php", {'isPostBack':1}, function(res){
if (res.match(/err/i)){
alert(res);
}
});
});
});
Then, in the php, just (echo('Error adding record')) for this jquery to see there's an error string in the response and pop up the error message.
Other methods would be to use json, or http status codes and $.ajaxError(function(){ alert('error adding'); });.

Answer 3

from what i can tell so far is you'll only need to pass in the product id in and you can do this by appending your $.post call with the value; this will pass to your php script as a query string variable. i'm not sure which php script you posted, but if you're sending your data with jquery, it's using post and not get, so you may need to make an adjustment there and the session data should be available regardless, since it's the same session.
again this is without seeing all the code and since some of it isn't labeled, it's hard to determine. another thing, i like to use $.ajax for most actions like this, you have a lot more room to define and structure, as well as create one generic ajax function to call the methods and post data, as well as make a response callback. here's the documentation for you to look into $.ajax
i hope this helps.