在类变量中存储连接

Question

I am wondering how i can store my connection in a class variable and then keep reusing it ? Right now my code looks like this

This function sets up my Connection right now and is called everytime

function setDB()
{
$serviceAccount = ServiceAccount::fromJsonFile('firebase_credentials.json');
$firebase = (new Factory)
->withServiceAccount($serviceAccount)
->create();
$db = $firebase->getDatabase();

return $db;
}

This is one of my functions which needs the connection $db to get and update Data.

function Period($gameid, $action) 
{
$db = setDB();
$reference = $db->getReference('games/'.$gameid.'/Clock/CurrentPeriode');
$value = $reference->getValue();

if ($action =='m')
{
    $value = $value -1;
    $db->getReference('games/'.$gameid.'/Clock/CurrentPeriode')
    ->set($value);
} else {
    $value = $value +1;
    $db->getReference('games/'.$gameid.'/Clock/CurrentPeriode')
    ->set($value);
}
}

Answer 1

The solution is using Singleton pattern:

class DbConn
{
    private $db;

    protected function  __construct()
    {
        $serviceAccount = ServiceAccount::fromJsonFile('firebase_credentials.json');
        $firebase = (new Factory)
            ->withServiceAccount($serviceAccount)
            ->create();
        $this->db = $firebase->getDatabase();
    }


    public function getInstance()
    {
        static $instance;

        if (!$instance) {
            $instance = new self();
        }

        return $instance;
    }

    public function getDb()
    {
        return $this->db;
    }

}

And usage will be looking like this:

function Period($gameid, $action) 
{
    $db = DbConn::getInstance()->getDb();
    $reference = .....