php - PDO user_data function -

so in init.php file checks see if user logged in, requires function called user_data($username)

here's contain.

init.php

if (logged_in() === true) {     $session_user_id = $_session['user_id'];     $user_data = user_data($session_user_id, 'user_id', 'username', 'password', 'first_name', 'last_name', 'email', 'coins', 'host', 'bets', 'online', 'multi');     $user_id = $user_data['user_id'];        if (user_active($user_data['username']) === false) {         session_destroy();         header('location: index.php');         exit();     } } 

the function user_data() is

function user_data($user_id){ $data = array(); $user_id = (int)$user_id;  $func_num_args = func_num_args(); $func_get_args = func_get_args();  if ($func_num_args > 1) {     unset($func_get_args[0]);      $fields = '`' . implode('`, `', $func_get_args) . '`';     $sql = sprintf('select `%s` `users` `id` = ? limit 1', $fields);     $stmt = $dbh->prepare($sql);     $stmt->execute(array($user_id));     $data = $stmt->fetch(pdo::fetch_assoc);      return $data; } } 

i error php fatal error: call member function prepare() on non-object because i'm not calling function $db or function incorrect?

you haven't connected database. should have pdo database connection inside user_data function, or global, or pass in.