在控制器中打开数据库连接（连接模式）

Question

I've got to implement a database connection pattern. I created two classes:

• ConnectionFactory
• MySQLService

ConnectionFactory:

<?php

  class ConnectionFactory {
    protected static $connection;

    public function getConnection() {
        if (!self::$connection) {
            self::$connection = new PDO('mysql:host=localhost;dbname=sapienter', "root", "admin");
        }
        return self::$connection;
    }
  }

?>

MySQLService:

<?php

  class MySQLService {
    protected $connectionFactory;

    public function __construct(ConnectionFactory $factory) {
      $this->connectionFactory = $factory;
    }

    public function listItemsForSharerSQL() {
      $conn = $this->connectionFactory->getConnection();
      $items = ...
      return $items;
    }
  }

?>

I call these methods in my controller ItemController :

<?php

require_once ROOT_DIR . "/models/Item.php";
require_once ROOT_DIR . "/ConnectionFactory.php";
require_once ROOT_DIR . "/MySQLService.php";

class ItemController {

    private $data;

    public function listItemsForSharer() {
        $connFactory = new ConnectionFactory();
        $service = new MySQLService($connFactory);
        $items = $service->listItemsForSharerSQL();

        $this->data = ['items' => $items];
        return 'itemslistforsharer-view';
    }
}

?>

I don't like the fact that I've got to instantiate a new ConnectionFactory in my Controller. Is it a mistake? Should I change my code design?

Answer 1

It is mistake that you are using a Database in a Controller at all. If talking about a Controller from the MVC Architecture pattern, then its Models job to interact with the database. There should be only instances of the Models in the controllers, but not instances of the Database.

Basically in the modern MVC frameworks that Models are extending the base Model class, which has the instantiation of the database.

As I understand, MySQLService is something like a model since you are returning some items, it seems like you are doing DB operation and want to handle it from a controller. Instead of every model having its own constructor, you should use a base class. I would suggest something like:

class Model {

    protected function getAdapter() {
        $connection = new ConnectionFactory();
        return $connection->getConnection();
    }

}


class MySQLService extends Model {

    public function listItemsForSharerSQL() {
      $this->getAdapter();
      $items = ...
      return $items;
    }
}

So now your controller will only need

$service = new MySQLService();

Ofcourse you base class can have the getAdapter() method as a constructor, without any params, so you won't need to pass anything to the MySQLService and won't need to call getAdapther() in each method of MySQLService . Depends on your needs.