PHP: Using DB-connection inside of class - php

Question

i'm updating from PHP5.6 to PHP7.0 and this doesn't work anymore:
$con=mysqli_connect(DATABASE_SERVER,DATABASE_USER,DATABASE_PASSWORD) or die(DATABASE_ERROR);
mysqli_select_db($con, DATABASE_NAME) or die(DATABASE_ERROR);
class DoSomeStuff()
{
function GetSomeDate()
{
$result=mysqli_query($con, "SELECT * FROM my_table");
}
}
Looks like the $con variable is not available inside the class.
Do i have to to something like this?
global $con=mysqli_connect()
Thanks!

Answer 1

The main pattern used is something like, pass database connection into constructor (dependency injection) and then store it in an instance variable ($this->con in this case). Then later database calls just use $this->con for the database connection...
$con=mysqli_connect(DATABASE_SERVER,DATABASE_USER,DATABASE_PASSWORD) or die(DATABASE_ERROR);
mysqli_select_db($con, DATABASE_NAME) or die(DATABASE_ERROR);
class DoSomeStuff
{
private $con;
// Create instance with connection
public function __construct( $con ) {
// Store connection in instance for later use
$this->con = $con;
}
public function doSomething() {
// Run query using stored database connection
$result=mysqli_query($this->con, "SELECT * FROM my_table");
}
}
// Create instance, passing in connection
$some = new DoSomeStuff ($con);
$some->doSomething();

Answer 2

heres something I've worked with recently
class Database {
private $_conn = null;
public function getConnection($password) {
if (!is_null($this->_conn)) {
return $this->_conn;
}
$this->_conn = false;
try {
$this->_conn = new PDO("mysql:host=localhost;dbname=databasename", 'root',
$password);
$this->_conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch(PDOException $e) {
echo "Connection failed: " . $e->getMessage();
}
return $this->_conn;
}
}
function conOpen() {
$servername = "localhost";
$username = "root";
$password = "password";
$db = new Database();
$conn = $db->getConnection($password);
return $conn;
}
Then use it like this
$con = conOpen();
You can check out PDO connection here