Prevent user from voting twice with cookie

[bob0011]

Hi there, im hoping someone can help me with this. What i’m trying to do is prevent users from voting twice with cookies, ive tried to set several myself but none of them have worked. Any help would be amazing. Thanks.

EDIT: unsure why its formatted this way.  how to fix? 

 

<?php include 'functions.php'; // Connect to MySQL $pdo = pdo_connect_mysql(); // If the GET request "id" exists (poll id)... if (isset($_GET['id'])) { // MySQL query that selects the poll records by the GET request "id" $stmt = $pdo->prepare('SELECT * FROM polls WHERE id = ?'); $stmt->execute([$_GET['id']]); // Fetch the record $poll = $stmt->fetch(PDO::FETCH_ASSOC); // Check if the poll record exists with the id specified if ($poll) { // MySQL query that selects all the poll answers $stmt = $pdo->prepare('SELECT * FROM poll_answers WHERE poll_id = ?'); $stmt->execute([$_GET['id']]); // Fetch all the poll anwsers $poll_answers = $stmt->fetchAll(PDO::FETCH_ASSOC); // If the user clicked the "Vote" button... if (isset($_POST['poll_answer'])) { // Update and increase the vote for the answer the user voted for $stmt = $pdo->prepare('UPDATE poll_answers SET votes = votes +1 WHERE id = ?'); $stmt->execute([$_POST['poll_answer']]); // Redirect user to the result page header ('Location: result.php?id=' . $_GET['id']); exit; } } else { die ('Poll with that ID does not exist.'); } } else { die ('No poll ID specified.'); } ?> <?=template_header('Poll Vote')?> <div class="content poll-vote"> <h2><?=$poll['title']?></h2> <p><?=$poll['des']?></p> <form action="vote.php?id=<?=$_GET['id']?>" onSubmit="disable()" method="post"> <?php for ($i = 0; $i < count($poll_answers); $i++): ?> <label> <input type="radio" name="poll_answer" value="<?=$poll_answers[$i]['id']?>"<?=$i == 0 ? ' checked' : ''?>> <?=$poll_answers[$i]['title']?> </label> <?php endfor; ?> <div> <input type="submit" name="submit" value="Vote"> <a href="result.php?id=<?=$poll['id']?>">View Result</a> </div> </form> </div> <?=template_footer()?>

 

Edited July 1, 2020 by requinix
cleaning up post

[bob0011]

I have no idea why it is formatted that way, is there a way to fix it? 

[Barand]

47 minutes ago, bob0011 said:

is there a way to fix it? 

Fixed. What editor are you using?

<?php 
include 'functions.php'; 
// Connect to MySQL 
$pdo = pdo_connect_mysql(); 
// If the GET request "id" exists (poll id)... 
if (isset($_GET['id'])) { 
    // MySQL query that selects the poll records by the GET request "id" 
    $stmt = $pdo->prepare('SELECT * FROM polls WHERE id = ?'); 
    $stmt->execute([$_GET['id']]); 
    // Fetch the record 
    $poll = $stmt->fetch(PDO::FETCH_ASSOC); 
    // Check if the poll record exists with the id specified 
    if ($poll) { 
        // MySQL query that selects all the poll answers 
        $stmt = $pdo->prepare('SELECT * FROM poll_answers WHERE poll_id = ?'); 
        $stmt->execute([$_GET['id']]); 
        // Fetch all the poll anwsers 
        $poll_answers = $stmt->fetchAll(PDO::FETCH_ASSOC); 
        // If the user clicked the "Vote" button... 
        if (isset($_POST['poll_answer'])) { 
            // Update and increase the vote for the answer the user voted for 
            $stmt = $pdo->prepare('UPDATE poll_answers SET votes = votes +1 WHERE id = ?'); 
            $stmt->execute([$_POST['poll_answer']]); 
            // Redirect user to the result page 
            header ('Location: result.php?id=' . $_GET['id']); 
            exit; 
        } 
    } 
    else { 
        die ('Poll with that ID does not exist.');
    }
} 
else { 
    die ('No poll ID specified.'); 
} 
?> 
<?=template_header('Poll Vote')?> 
<div class="content poll-vote"> 
    <h2><?=$poll['title']?></h2>
    <p><?=$poll['des']?></p> 
    <form action="vote.php?id=<?=$_GET['id']?>" onSubmit="disable()" method="post"> 
        <?php 
        for ($i = 0; $i < count($poll_answers); $i++): 
        ?> 
            <label> 
                <input type="radio" name="poll_answer" value="<?=$poll_answers[$i]['id']?>" <?=$i == 0 ? ' checked' : ''?>> 
                <?=$poll_answers[$i]['title']?> 
            </label> 
        <?php endfor; ?> 
        <div> 
            <input type="submit" name="submit" value="Vote"> 
            <a href="result.php?id=<?=$poll['id']?>">View Result</a> 
        </div> 
    </form> 
</div> 
 <?=template_footer()?>

 

[bob0011]

6 minutes ago, Barand said:

Fixed. What editor are you using?

<?php 
include 'functions.php'; 
// Connect to MySQL 
$pdo = pdo_connect_mysql(); 
// If the GET request "id" exists (poll id)... 
if (isset($_GET['id'])) { 
    // MySQL query that selects the poll records by the GET request "id" 
    $stmt = $pdo->prepare('SELECT * FROM polls WHERE id = ?'); 
    $stmt->execute([$_GET['id']]); 
    // Fetch the record 
    $poll = $stmt->fetch(PDO::FETCH_ASSOC); 
    // Check if the poll record exists with the id specified 
    if ($poll) { 
        // MySQL query that selects all the poll answers 
        $stmt = $pdo->prepare('SELECT * FROM poll_answers WHERE poll_id = ?'); 
        $stmt->execute([$_GET['id']]); 
        // Fetch all the poll anwsers 
        $poll_answers = $stmt->fetchAll(PDO::FETCH_ASSOC); 
        // If the user clicked the "Vote" button... 
        if (isset($_POST['poll_answer'])) { 
            // Update and increase the vote for the answer the user voted for 
            $stmt = $pdo->prepare('UPDATE poll_answers SET votes = votes +1 WHERE id = ?'); 
            $stmt->execute([$_POST['poll_answer']]); 
            // Redirect user to the result page 
            header ('Location: result.php?id=' . $_GET['id']); 
            exit; 
        } 
    } 
    else { 
        die ('Poll with that ID does not exist.');
    }
} 
else { 
    die ('No poll ID specified.'); 
} 
?> 
<?=template_header('Poll Vote')?> 
<div class="content poll-vote"> 
    <h2><?=$poll['title']?></h2>
    <p><?=$poll['des']?></p> 
    <form action="vote.php?id=<?=$_GET['id']?>" onSubmit="disable()" method="post"> 
        <?php 
        for ($i = 0; $i < count($poll_answers); $i++): 
        ?> 
            <label> 
                <input type="radio" name="poll_answer" value="<?=$poll_answers[$i]['id']?>" <?=$i == 0 ? ' checked' : ''?>> 
                <?=$poll_answers[$i]['title']?> 
            </label> 
        <?php endfor; ?> 
        <div> 
            <input type="submit" name="submit" value="Vote"> 
            <a href="result.php?id=<?=$poll['id']?>">View Result</a> 
        </div> 
    </form> 
</div> 
 <?=template_footer()?>

 

Hi there, i am using sublime text 3 

[StevenOliver]

4 hours ago, bob0011 said:

prevent users from voting twice

ahhhhh, if only........ 😀

[Barand]

Ensure users have to log in before they can vote so you know their user_id.

When they vote, store the poll_id and user_id.

Put a unique constraint on (poll_id, user_id) so that combination can not be added twice.

[maxxd]

Set a cookie or local storage key when someone votes; check for it before you process a vote. Admittedly, if your poll is available for a long time this won't be greatly effective, but if you poll is only up for a day or so it could work.

Edited July 3, 2020 by maxxd