Before starting the topic, create two new files in controllers directory:

1. destroy.php that contains the code used to delete a note from the database.
2. store.php that contains the code to create a new note using forms and request methods.

Intro to Service Container

A Service Container is a design pattern that centralizes the management of dependencies between objects, providing a structured way to access and manage services within an application.

It acts as a registry for services within a website.

Container Class

Firstly create a file named Controller.php in Core directory. In this initialize the Container class, that is responsible for managing service bindings and resolutions.

• bind(): Registers a service with the container.
• resolve(): Retrieves a service from the container.

class Container {
    protected $bindings = [];

    public function bind($key, $resolver) {
        $this->bindings[$key] = $resolver;
    }

    public function resolve($key) {
        if (!array_key_exists($key, $this->bindings)) {
            throw new Exception("No matching binding found for {$key}");
        }
        $resolver = $this->bindings[$key];
        return call_user_func($resolver);
    }
}

App Class

The App class acts as a interface for the Container, providing a convenient interface for accessing services.

• setContainer(): Sets the container instance for the App.
• container(): Retrieves the container instance.
• bind(): Registers a service with the container.
• resolve(): Retrieves a service from the container.

class App {
    protected static $container;

    public static function setContainer($container) {
        static::$container = $container;
    }

    public static function container() {
        return static::$container;
    }

    public static function bind($key, $resolver) {
        static::container()->bind($key, $resolver);
    }

    public static function resolve($key) {
        return static::container()->resolve($key);
    }
}

Bootstrap

Bootstrap is a point of an application, where everything is set up and initialized.

$container = new Container();
$container->bind('Core\Database', function () {
    $config = require base_path('config.php');
    return new Database($config['database']);
});
App::setContainer($container);

In this , the bootstrap process:

1. Creates a new Container instance ($container)
2. Registers services with the container using the bind method (e.g., Core\Database)
3. Sets the container for the App using App::setContainer($container)

Controller

Services can be resolved from the container in controllers using the App::resolve() method.

$db = App::resolve('Core\Database');

Now a service container is properly built and you can see the project is working well.

I hope that you have clearly understood it.