Update Voting System By Alena Holligan

I had to load the page to see how the voting works. If you already voted for a book clicking either arrow removes the vote. This means a user can only vote once per book and is accomplished with clearVote.

clearVote attempts to delete a vote based on bookid and userid.

Here is the function:

function clearVote($bookId, $userId)
{
    global $db;

    try {
        $query = "DELETE FROM votes WHERE book_id = :bookId AND user_id = :userId";
        $stmt = $db->prepare($query);
        $stmt->bindParam(':bookId', $bookId);
        $stmt->bindParam(':userId', $userId);
        $stmt->execute();
        return $stmt->rowCount();
    } catch (\Exception $e) {
        throw $e;
    }
}

If you check the return statement for clearVote you will see a rowCount is returned. This is a count of the number of records affected by the delete query. If any records were deleted the value will be positive. This adjustment is considered a vote. So the following returns true and the vote function is exited

if (clearVote($bookId, $userId)) {
        return true;
    }

If no vote records were deleted, then the user hasn't voted yet and the vote function proceeds to add a new vote.

Yes. The user will have no votes in the vote table for that book. With no votes, on a subsequent vote clearVote will return a recordCount of 0 which is equivalent to false. So a new vote will be recorded.

Hi KRIS NIKOLAISEN, thank you for your help on this issue. So, if the user has voted, then the clearVote function will run and remove the entry in the votes table and return a positive count, then return true and exit the vote function. Please excuse my confusion but does that mean the user has no longer got a vote for the book in the votes table as it has been deleted?