oop cant get this small script to work properly logging in - php

Question

I can't figure out why this isn't working. I'm new and just learning.
login.php
<?php
include 'core/init.php';
if (empty($_POST) === false) {
$username = $_POST['username'];
$password = $_POST['password'];
$user = new User();
if (empty($username) === true || empty($password) === true) {
echo 'you need to enter a username and password';
} else if ($user->userExists($username) === false) {
echo 'we cant find that username. have you registered?';
} else echo 'ok';
}
?> <?php
include 'core/init.php';
if (empty($_POST) === false) {
$username = $_POST['username'];
$password = $_POST['password'];
$user = new User();
if (empty($username) === true || empty($password) === true) {
echo 'you need to enter a username and password';
} else if ($user->userExists($username) === false) {
echo 'we cant find that username. have you registered?';
} else echo 'ok';
}
?> <?php
include 'core/init.php';
if (empty($_POST) === false) {
$username = $_POST['username'];
$password = $_POST['password'];
$user = new User();
if (empty($username) === true || empty($password) === true) {
echo 'you need to enter a username and password';
} else if ($user->userExists($username) === false) {
echo 'we cant find that username. have you registered?';
} else echo 'ok';
}
?>
User.php
<?php
require_once 'core/classes/Connect.php';
class User {
private $db;
public function __construct() {
$this->db = new Connect();
$this->db = $this->db->dbConnect();
}
public function userExists($username) {
$st = $this->db->prepare("SELECT COUNT(user_id) FROM users WHERE username=?");
$st->bindParam(1, $username);
$st->execute();
if ($st->rowCount() == 1) {
return true;
} else return false;
}
}
?>
Ive been tring to learn OOP and everyone tells me the best way to learn is to try rather than ask for help. I'm tring to build a simple login and then make it more complex.
When I enter the correct username it doesn't echo ok. Instead, it echos we can't find that username. Have you registered? Any help please. Thanks

Answer 1

I don't know how your Connect-class (and especially the method rowCount) works, but the problem seems to be the following: Your query returns the number of user_ids with the given username but you count rows.
Replacing
$st = $this->db->prepare("SELECT COUNT(user_id) FROM users WHERE username=?");
with
$st = $this->db->prepare("SELECT user_id FROM users WHERE username=?");
should do the trick.
And since you are learning some more comments:
empty($username) === true is equal to empty($username). Most programmers prefer the latter (since its shorter).
Also it seems to make more sense to declare the method userExists as static.