ajax check user logged in before running script

Question

i have a pretty basic voting system i have implemented on my site. using the following ajax when a user clicks on the link there vote is added to the database and the vote is updated +1.

this all works fine but i would like to check if the user is logged in before allowing them to vote if there not display an error pop up or redirect to the login page (eventually i will display a lightbox popup asking for them to login or register.

<script type="text/javascript">
    $(document).ready(function() {
        $(".voteup a").click(function() {
            var ID = <?php echo $moviedetails['id'] ?>
            //$("#vote").text();
            var rating = <?php echo $vote['vote_up'] ?>
            var queryString = 'id=' + ID + '&vote=' + rating;
            $("#voteup").text (rating + 1);
            $.ajax({
                type: "POST",
                url: "vote_up.php",
                data: queryString,
                cache: false,
                success: function(html) {
                    $("#votethanks").html('Thanks');
                    $("#votethanks").slideDown(200).delay(2000).fadeOut(2000);
                }
            });
        });
    });
</script>

and vote_up.php

<?php
require_once("header.php");

$data = $_POST['id'];   

$updatevote = "UPDATE `vote` SET `vote_up` = vote_up +1 WHERE `movie_id` = '$data'";
mysqli_query($con, $updatevote);

?>

i have tried

if (!(isset($_SESSION['sess_user_id']) && $_SESSION['sess_user_id'] != '')) {
echo "<script>alert('Please login.')</script>";
}
else { //then the javascript

but it just checks the users logged in on page load, if there not it displays the please login error, but i need it to do this onclick of the javascript.

any help appreciated

thanks lee

Ramy Nasr · Accepted Answer · 2014-05-26 18:34:20Z

You can consider doing the check with PHP in the vote_up.php and check the response in your ajax. Something like this:

$.ajax({
    type: "POST",
    url: "vote_up.php",
    data: queryString,
    cache: false,
    success: function(result) {
        if (result.error) {
            alert(result.msg);
        } else {
            $("#votethanks").html(result.msg);
            $("#votethanks").slideDown(200).delay(2000).fadeOut(2000);
        }
    }
});

in your vote_up.php:

<?php

if (!(isset($_SESSION['sess_user_id']) && $_SESSION['sess_user_id'] != '')) {

    // User is not logged in!
    $result = array(
        'error' => true,
        'msg' => 'Please login first!'
    );

} else {

    // write the needed code to save the vote to db here

    $result = array(
        'error' => false,
        'msg' => 'Thanks!'
    );
}

// Return JSON to ajax call
header('Content-type: application/json');
echo json_encode($result);

Reed Spool · Accepted Answer · 2014-05-26 18:06:26Z

0

Why not use your PHP to insert into a authenticated variable, just as you do with vote and ID?

For example:

var authenticated = <?php !(isset($_SESSION['sess_user_id']) && $_SESSION['sess_user_id'] != '') ?>

Note: Completely untested. I just copied and pasted the php code from your "I have tried..."

Does this help?

answered May 26, 2014 at 18:06

Reed Spool

8397 silver badges16 bronze badges

Comments

boortmans · Accepted Answer · 2014-05-26 18:43:22Z

0

Add a boolean. Every time the user clicks on the voting, send an ajax call to check if the user is logged in.

$(document).ready(function()
{
    $(".voteup a").click(function()
    {
        var the_user_is_logged_in;
        the_user_is_logged_in = checkLoggedIn();
        if the_user_is_logged_in{
            // do ajax call
        }
        else{
            alert('Please log in!')
        }
     }
 }

 function checkLoggedIn(){
    $.get('getsession.php', function (data) {
        return data;
    });

And in getsession.php you should write

<?php
session_start();
print json_encode($_SESSION);

I didn't try the code, but it should work.

edited May 26, 2014 at 18:43

answered May 26, 2014 at 18:14

boortmans

1,1604 gold badges24 silver badges42 bronze badges

1 Comment

Sachin Over a year ago

the variable the_user_is_logged_in is always returned to UNDEFINED.

Iwan Ross · Accepted Answer · 2018-05-01 06:45:23Z

This is what worked for me in the end. I am only sharing this to help someone who my encounter the same problem and end up with a migraine.

The ajax script:

<script type="text/javascript">
function review_likes ( addresscommentid ) 
{ $.ajax( { type    : "POST",
async   : false,
data    : { "txt_sessionid" : addresscommentid }, 
url     : "functions/review_likes.php",
beforeSend: function() {
    // checking if user is logged in with beforeSend
   <?php if (!(isset($_SESSION['signed_in_uid']) && 
$_SESSION['signed_in_uid'] 
   != '')) { ?>        
       $(window.location.href = 'admin/index-signin.php');  
    <?php } ?>
    },
success : function ( sessionid )

{ 
$('#reviewlikes').removeClass('like-action'); 
$('#reviewlikes').load(document.URL +  ' #reviewlikes');       
},
error   : function ( xhr )
{ 
alert( "You are not Logged in" );
}
 });

 return false;

}
</script>

On the review_likes.php page header:

<?php 

$kj_authorizedUsers = "";
$kj_restrictGoTo = "../admin/index.php";
if (!((isset($_SESSION['kj_username'])) && 
(isAuthorized("",$kj_authorizedUsers, 
$_SESSION['kj_username'], $_SESSION['kj_authorized'])))) {   
$kj_qsChar = "?";
$kj_referrer = $_SERVER['PHP_SELF'];
if (strpos($kj_restrictGoTo, "?")) $kj_qsChar = "&";
if (isset($_SERVER['QUERY_STRING']) && strlen($_SERVER['QUERY_STRING']) > 0) 
$kj_referrer .= "?" . $_SERVER['QUERY_STRING'];
$kj_restrictGoTo = $kj_restrictGoTo. $kj_qsChar . "accesscheck=" . 
urlencode($MM_referrer);
header("Location: ". $kj_restrictGoTo); 
exit;
} 
?>

The above code is a bit overkill, but it helps to get the current URL and redirect the user to the requesting page after successful login.

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