About OOP, using PHP [duplicate] - php

Question

I really hope someone can help me figure out what I am missing. I have upgraded my installation from PHP 5.6 to 7.0 and this has forced me to update from Mysql to Mysqli which for some reason has broken my setup.
I researched and followed this guide "Using MySQLi in other classes": Using MySQLi in other classes
I am writing as a last resort and have looked at other sites as well but it seems like the problem comes some where else from.
First I have a database class:
private $serverName = "localhost";
private $userName = "DBUserName";
private $pass = "UserPassword";
private $database = "SelectedDB";
public $conn;
public function __construct(){
$this->conn = new mysqli($this->serverName, $this->userName,$this->pass,$this->database);
}
Then I have an API class where I want to access this connection which looks like
require_once 'Database.php';
class MyAPI{
private $db;
public function __construct($request_uri, $postData, $origin) {
$this->db = new Database();
}
and lastly i try to call it from a function:
$getUserResult = mysqli_query( $this->db->conn, $getUserQry);
When ever I call $this->db->conn I get an internal server error 500
If I create the database connection in the MyAPI class there is no issues which seems odd to me.
I hope someone can point me in a direction.
UPDATE:
I corrected a spelling error in the script and now I get 200 but the value still continues to be null from the query mysqli_query.
If i create the $dbtest = new database(); and use that instead it works fine. Is there someway to get it to work inside the constructor with the reference to $db?

Answer 1

There are several bad practices that led you to this error.
Clearly, extending User from a Database is a wrong move. Also, the whole Database class is rather useless as it doesn't do anything useful.
Hence I would suggest to
get rid of the useless Database class.
create a single $db instance from vanilla mysqli.
pass it as a constructor parameter into every class that needs a database connection
database.php:
<?php
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$db = new mysqli("localhost", "DBUserName", "UserPassword", "SelectedDB");
$db->set_charset('utf8mb4');
myapi.php
<?php
class MyAPI
{
protected $db;
public function __construct($db, $request_uri, $postData, $origin)
{
$this->db = $db;
}
public function getUser($id)
{
$sql = "SELECT * FROM users where id=?";
$stmt = $this->db->prepate($sql);
$stmt->bind_param("s", $id);
$stmt->execute();
$result = $stmt->get_result();
return $result->fetch_assoc();
}
}
app.php
<?php
# require_once 'Database.php';
# require_once 'myapi.php';
require 'vendor/autoload.php'; // autoloading is a must
$api = new MyAPI($db, $request_uri, $postData, $origin);
$user = $api->getUser($_POST['id']);