Symfony Flex - How to create a database mysql connection - php

Question

I am a beginner on Symfony.
I am trying to create a class to use my database (mysql). But I can not succeed. Can you help me ?
Here is my current class:
<?php
namespace App\Database;
use Doctrine;
use Doctrine\DBAL\Connection;
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
class DatabaseApi extends AbstractController
{
/**
* #var Connection
*/
protected $database = null;
protected static $instance = null;
/**
* DatabaseApi constructor.
*/
protected function __construct()
{
$database = $this->container->get('database');
$this->database = $database;
}
public static function getInstance()
{
self::$instance = new self();
return self::$instance;
}
private function __clone()
{
}
/**
* #param $authentication_key
* #return mixed
* #throws Doctrine\DBAL\DBALException
*/
public function select_authentication_key($authentication_key)
{
$auth_key_query = $this->database->prepare('CALL Verify_authentication_key(:authentication_key)');
$auth_key_query->bindValue('authentication_key', $authentication_key);
$auth_key_query->execute();
$results = $auth_key_query->fetchAll(\PDO::FETCH_ASSOC);
return $results[0];
}
}
I tried to create it with everything I could find on the Internet. Unfortunately, I get an error "Call to a member function get() on null".
There is my services.yaml file :
parameters:
database_connection: default
services:
# default configuration for services in *this* file
_defaults:
autowire: true # Automatically injects dependencies in your services.
autoconfigure: true # Automatically registers your services as commands, event subscribers, etc.
public: false # Allows optimizing the container by removing unused services; this also means
# fetching services directly from the container via $container->get() won't work.
# The best practice is to be explicit about your dependencies anyway.
# makes classes in src/ available to be used as services
# this creates a service per class whose id is the fully-qualified class name
App\:
resource: '../src/*'
exclude: '../src/{DependencyInjection,Entity,Migrations,Tests,Kernel.php}'
# controllers are imported separately to make sure services can be injected
# as action arguments even if you don't extend any base controller class
App\Controller\:
resource: '../src/Controller'
tags: ['controller.service_arguments']
# add more service definitions when explicit configuration is needed
# please note that last definitions always *replace* previous ones
database:
alias: doctrine.dbal.%database_connection%_connection
And is is how I try to call the fonction :
$database = DatabaseApi::getInstance();
$result = null;
try{
$result = $database->select_authentication_key("1111-1111-1111-1111");
}catch (Exception $e){
print($e);
}
print_r($result);