MySQLI Update Not Working and Not Returning Any Errors

Question

I am trying to right a script to update users in my database here is my code:

I get the user data from a form:

$user = new User();

if (isset($_POST['submit'])) {
  // Process the form

  // validations
  // $required_fields = array("username", "password");
  // validate_presences($required_fields);

  // $fields_with_max_lengths = array("username" => 30);
  // validate_max_lengths($fields_with_max_lengths);

  $errors = ""; //temp

  if (empty($errors)) {

    $user->username = $db->mysql_prep($_POST["username"]);
    $user->hashed_password = ($_POST["password"]);
    $user->first_name = $db->mysql_prep($_POST["first_name"]);
    $user->last_name = $db->mysql_prep($_POST["last_name"]);
    $user->id = $db->mysql_prep($_POST["id"]);

    print_r($user);

    $user_by_id = $user->find_user_by_id($user->id);

    print_r($user_by_id);

    $result = $user->change_user_by_id($user_by_id);

    //->id,$user->username,$user->hashed_password,$user->firstname,$user->lastname

    unset($user);
}

Here is my find_user_by_id method:

public static function find_user_by_id($id=0){

global $db; 

$query  = "SELECT * ";
$query .= "FROM users ";
$query .= "WHERE id = {$id} ";
$query .= "LIMIT 1";

$user_set = mysqli_query($db->connection, $query);
$db->confirm_query($user_set);

if($user = mysqli_fetch_object($user_set)) {
    return $user;
} else {
    return null;
}   
}

And finally my change_user_by_id method:

public function change_user_by_id($user){
    global $db; 
    global $session;

    $query  = "UPDATE users SET ";
    $query .= "username = '{$user->username}', ";
    $query .= "first_name = '{$user->first_name}', ";
    $query .= "last_name = '{$user->last_name}' ";
    $query .= "WHERE id = {$user->id} ";
    $query .= "LIMIT 1";

    $result = mysqli_query($db->connection, $query);
    $db->confirm_query($result);

    if ($result && mysqli_affected_rows($db->connection) == 1) {
          // Success
        $session->message("User updated.");
        redirect_to("list.php");
    } else {
          // Failure
        $session->message("User update failed.");
        redirect_to("change.php?id={$user->id}");

    }
}

When I try to update a user I get redirected to change.php with the error message user update failed. I've been trying to work through the logic and I just can't seem to find where I've gone wrong. The print_r were added later to see if the objects had the proper values, and they did.

EDIT 1:

I changed some code to see what mysqli_affected_rows returns and it returns 0.

You won't get an answer for offtopic question, no matter how many times you post a duplicate. — Your Common Sense, Feb 22 '14 at 19:33
This isn't a duplicate question, this a different problem. And what do you mean by off topic? I think I figured out my first problem. I think it was caused by using the username to get the id, which means changing the username meant no id could be retrieved. So I changed my code and added a hidden field for id in my form. But I can't be sure if this fixed the first problem because it caused this second problem. — Praveen Perera, Feb 22 '14 at 19:44

score 0 · Answer 1 · edited May 23 '17 at 12:03

After many hours I finally figured it out i just had to take out the line:

$user_by_id = $user->find_user_by_id($user->id);

and change the line:

$result = $user->change_user_by_id($user_by_id);

to:

 $result = $user->change_user_by_id($user);

This line was a remnant of the way I was doing it before and it caused my to send the original data instead of the new data to the change method.

MySQLI Update Not Working and Not Returning Any Errors

1 Answers1