MySQLi database connection - php

Question

I have this (from someone else derived from my first attempt at a database class):
require_once( "declarations.php" );
class Database{
private static $mysqli;
private static $dbName = '';
private static $username = '';
private static $password = '';
private static $host = 'localhost';
private static $prefix = '';
public function __construct(){
if( self::$host & self::$username & self::$password & self::$dbName )
{
self::$mysqli = new mysqli( self::$host, self::$username, self::$password, self::$dbName );
if (self::$mysqli->connect_error) {
die('Connect Error (' . self::$mysqli->connect_errno . ') '
. self::$mysqli->connect_error);
}
}
else
{
echo "You forgot to fill in your database connection details";
}
}
public function Query( $query ){
$query = self::$mysqli->real_escape_string( $query );
if ($query = self::$mysqli->prepare($query)) {
$query->execute();
$query->store_result();
$stmt = $query->result;
//$query->mysql_num_rows = $stmt->num_rows();
$query->close();
return $stmt;
}
}
public function Close()
{
self::$mysqli->close();
}
}
This is how i'm calling it:
include_once( "system/database.php" );
$query = "SELECT * FROM app";
$dbr = new Database();
//Change this here since your method is query and not $mysqli
while( $row = $dbr->Query( $query )->fetch_object() ){
echo '<td>'. $row['id'] . '</td>' ;
echo '<td>'. $row['title'] . '</td>' ;
}
Database::Close();
I am getting an error Call to a member function fetch_object() on a non-object in on the while loop.
Any ideas?

Answer 1

fetch_object works with result set returned after query is executed with methods like: mysql_query or use fetch_assoc instead with
$query->execute();
$result = $query->get_result();
while ($myrow = $result->fetch_assoc()) {
//Your logic
}

Answer 2

Well, your first attempt resulted with totally unusable code.
There are 2 critical faults and one serious one.
As I told you already, doing $query = self::$mysqli->real_escape_string( $query ); is useless and harmful at once. You have to get rid of this line. Completely and forever.
Preparing a query without binding variables is totally useless.
You have to check for mysql errors.
So, at the very least your query() function have to be
public function query($query)
{
$res = self::$mysqli->query($query);
if (!$res)
{
throw new Exception(self::$mysqli->error);
}
return $res;
}
But again - this function is not safe as it's not not implementing placeholders to substitute data in the query.