php oop check if user exists? - php

Question

I want to display an error if a username exists, however no error is being thrown.
the function is on the User.php and im trying to display an error from that function.
i referenced this, however it is not relevant to the OOP way.
User.php
public function check_user_exists($username)
{
try{
$stmt = $this->db->prepare("SELECT user_name FROM users WHERE user_name=:username");
$stmt->execute(array(':username'=>$username));
$row = $stmt->fetch(PDO::FETCH_ASSOC);
$row['user_name'] == $username;
}
catch(PDOExeception $e)
{
echo $e->getMessage();
}
}
Index.php
<?php
session_start();
require_once 'User.php';
$guest = new User();
if($guest->is_logged())
{
$guest->redirect('profile');
}
if (isset($_POST['btn_signup']) ){
$username = htmlentities($_POST['txt_username']);
$unpass = htmlentities($_POST['txt_password']);
$password = password_hash($unpass, PASSWORD_BCRYPT, ['cost' => 12] );
$unemail = $_POST['txt_email'];
$email = filter_var($unemail, FILTER_VALIDATE_EMAIL);
$guest = new User();
if($email == ""){
$errors[]= "Enter a Email";
}
if($username == ""){
$errors[]= "Enter a Username please";
}
if($password == ""){
$errors[]= "Enter a Password";
}
if($guest->check_user_exists($username)){
$errors[]= "Username Already Taken";
}
if($guest->signup($email,$password,$username)){
$guest->redirect('profile');
die('didnt redirect');
}
else{
$errors[]= "Invalid Entry";
}
}
$title = "Home";
require_once 'layouts/header.php';
?>
<div class="container">
<div class="row">
<div class="col-md-6">
<?php
if(isset($errors))
{
foreach($errors as $error)
{
?>
<div class="alert alert-danger">
<i class="glyphicon glyphicon-warning-sign"></i> <?php echo $error; ?>
</div>
<?php
}
}
else if(isset($_GET['joined']))
{
?>
<div class="alert alert-info">
<i class="glyphicon glyphicon-log-in"></i> Successfully registered <a href='index.php'>login</a> here
</div>
<?php
}
?>
<h1>Sign Up</h1>
<form action ="" method="POST">
<div class="form-group">
<label for="Email">Email address</label>
<input type="email" class="form-control" aria-describedby="emailHelp" name="txt_email" placeholder="Enter email">
</div>
<div class="form-group">
<label for="Username">Username</label>
<input type="text" class="form-control" aria-describedby="emailHelp" name="txt_username" placeholder="Enter Username">
</div>
<div class="form-group">
<label for="Password">Password</label>
<input type="password" class="form-control" aria-describedby="emailHelp" name="txt_password" placeholder="Enter password">
</div>
<button type="submit" name="btn_signup" class="btn btn-primary">Submit</button>
</form>
</div>
</div>
</div>
</body>
</html>

Answer 1

public function check_user_exists($username)
{
try{
$stmt = $this->db->prepare("SELECT user_name FROM users WHERE user_name=:username");
$stmt->execute(array(':username'=>$username));
return $stmt->fetchColumn() > 0; // fetchColumn return the number of rows selected
}
catch(PDOExeception $e)
{
echo $e->getMessage();
}
}

Answer 2

Your function doesn't actually return or do anything. Return the result of fetch(), if it returns true - a result was found. If it returns false, there was no row matching the username. You don't need to check anything after that, as the fetch() method will only be true if a result was found.
Adjusted for that, your function would look like this
public function check_user_exists($username) {
try{
$stmt = $this->db->prepare("SELECT user_name FROM users WHERE user_name=:username");
$stmt->execute(array(':username' => $username));
return $stmt->fetch(PDO::FETCH_ASSOC);
} catch(PDOExeception $e) {
echo $e->getMessage();
}
}
Also, its not a good idea to output errors directly (on a testing/development environment its fine, but on a live environment you should log it (error_log()) instead.
http://php.net/manual/en/pdostatement.fetch.php

Answer 3

public function ifUserAlreadyExist(string $email):bool{
$sql = "SELECT 1 FROM users WHERE email= :Email";
$statment = $this->conn->prepare($sql);
if (false === $statment) {
return false;
}
$statment->execute([':Email' => $email]);
return (bool)$statment->fetchColumn();
}
//You need to just select 1 object if is already exist and in this case function hint will be so handy, can set the function to boolean and see if it return true or false.
I hope I could help.