PHP & SQL : Throws fatal error when $_Request are filled - php

Question

I just started learning, but why is it that when I don't fill the info in the URL it connects to the database, but when I fill it in it gives a fatal error?
Ex. when I type
http://ehlien.com/php/signup.php?firstname=Mohamed&lastname=Mohamed&username=alpha&email=mohamed.mohd#hotmail.com&password=mohamed
It throws:
Fatal error: Uncaught exception 'Exception' with message 'Failed to connect to database' in /home/torokage/public_html/php/classes/DB.class.php:22 Stack trace: #0 /home/torokage/public_html/php/signup.php(35): DB->connect() #1 {main} thrown in /home/torokage/public_html/php/classes/DB.class.php on line 22
But when I type
http://ehlien.com/php/signup.php
It gives me my error I set up:
{"status":"400","message":"Please fill in the missing information..."}
I don't have a lot of knowledge on php and mysql, just trying to figure it out on my own and through some tutorials but I can't get this to work to continue...
CODE, signup.php:
<?php
require('classes/User.class.php');
require('classes/DB.class.php');
require('classes/Connection.class.php');
$firstname = null;
$lastname = null;
$username = null;
$email = null;
$password = null;
$repassword = null;
if (empty($_REQUEST["firstname"]) ||
empty($_REQUEST["lastname"]) ||
empty($_REQUEST["username"]) ||
empty($_REQUEST["email"]) ||
empty($_REQUEST["password"]))
{
$returnError["status"] = "400";
$returnError["message"] = "Please fill in the missing information...";
echo json_encode($returnError);
return;
}
$firstname = htmlentities($_REQUEST["firstname"]);
$lastname = htmlentities($_REQUEST["lastname"]);
$username = htmlentities($_REQUEST["username"]);
$email = htmlentities($_REQUEST["email"]);
$password = md5(htmlentities($_REQUEST["password"]));
$DB = new DB(Connection::$db_host, Connection::$db_name, Connection::$db_user, Connection::$db_pass);
$DB->connect();
$checkUsername = $DB->checkIfUsernameExists($username);
if (!empty($checkUsername))
{
$returnError["status"] = "400";
$returnError["message"] = "That username has already been taken. Please try again...";
echo json_encode($returnError);
return;
}
$checkEmail = $DB->checkIfEmailExists($email);
if (!empty($checkEmail))
{
$returnError["status"] = "400";
$returnError["message"] = "That email has already been taken. Please try again...";
echo json_encode($returnError);
return;
}
$signUpUser = $DB->signUpUser($firstname, $lastname, $username, $email, $password);
if ($signUpUser)
{
$userDetails = $DB->getUserDetails($username);
$user["status"] = "200";
$user["message"] = "Success! You have now been registered.";
$user["ID"] = $userDetails["ID"];
$user["firstname"] = $userDetails["firstname"];
$user["lastname"] = $userDetails["lastname"];
$user["username"] = $userDetails["username"];
$user["email"] = $userDetails["email"];
}
else
{
$user["status"] = "400";
$user["message"] = "Sorry, this account has already been taken. Please try again...";
}
$DB->disconnect();
echo json_encode($user);
?>
DB.class.php
<?php
class DB {
protected $db_host = null;
protected $db_name = null;
protected $db_user = null;
protected $db_pass = null;
protected $db_conn = null;
protected $db_resu = null;
// Constructor
function __construct($db_host, $db_name, $db_user, $db_pass) {
$this->db_host = $db_host;
$this->db_name = $db_name;
$this->db_user = $db_user;
$this->db_pass = $db_pass;
}
// Connect to database
public function connect() {
$this->db_conn = new MySQLi($this->db_host, $this->db_name, $this->db_user, $this->db_pass);
if (mysqli_connect_errno())
throw new Exception("Failed to connect to database");
$this->db_conn->set_charset("utf8");
}
// Disconnect from database
public function disconnect() {
if ($this->db_conn != null)
$this->db_conn->close();
}
// Check if username exists
public function checkIfUsernameExists($username) {
$result = mysql_query("SELECT USERNAME FROM USERS WHERE EMAIL = '$username'");
if(mysql_num_rows($result) == 0){
return false;
} else {
return true;
}
}
// Check if email exists
public function checkIfEmailExists($email) {
$result = mysql_query("SELECT EMAIL FROM USERS WHERE EMAIL = '$email'");
if(mysql_num_rows($result) == 0){
return false;
} else {
return true;
}
}
// Get user informationd
public function getUserDetails($username) {
$command = mysql_query("SELECT * FROM USERS WHERE USERNAME = '$username'");
$value = array();
$result = $this->db_conn->query($command);
if ($result != null && (mysqli_num_rows($result) >= 1)) {
$row = $result->fetch_array(MYSQLI_ASSOC);
if (!empty($row)) {
$value = $row;
}
}
return $value;
}
// Sign up new user
public function signUpUser($firstname, $lastname, $username, $email, $password) {
$command = "INSERT INTO USERS SET FIRSTNAME=?, LASTNAME=?, USERNAME=?, EMAIL=?, PASSWORD=?";
$sql = $this->db_conn->prepare($command);
if (!$sql)
throw new Exception($sql->error);
$sql->bind_param("sssss", $firstname, $lastname, $username, $email, $password);
$value = $sql->execute();
return $value;
}
}
?>

Answer 1

When you didn't use any value or parameters, it's showing the error set up by you because it couldn't pass the validation step set up by you.
But when you are passing the values or parameters, it passes your validation and tries to connect with the database first as per this code of yours:
$DB = new DB(Connection::$db_host, Connection::$db_name, Connection::$db_user, Connection::$db_pass);
$DB->connect();
But it throws an exception: Failed to connect to database meaning that your database connection credentials are wrong and thus, can not connect with the database.
You may get more friendly error message by changing inside the public function connect() of DBclass to this:
// Connect to database
public function connect() {
try {
$this->db_conn = new MySQLi($this->db_host, $this->db_name, $this->db_user, $this->db_pass);
$this->db_conn->set_charset("utf8");
} catch (Exception $e ) {
echo "Failed to connect to database";
echo "Error: " . $e->message; // remove when in live...
}
}