Mezon Router: middleware and parameters modification

#middleware #mezon #router

Types of middlewares that you can add which will be called before the route handler will be executed. This middleware can transform common parameters $route and $parameters into something different.

Multiple global middlewares that will be called in order of attachment
Multiple route specific middlewares that will be called in order of attachment

Order of execution of the middlewares

Global middlewares $router->addRoute('*', ...)
Before calling route callback $router->addRoute('/example', ...) all those matching the route will be executed

Let's look at a simple example:

$router = new Router();
$router->addRoute('/user/[i:id]', function(string $route, array $parameters){
    $userModel = new UserModel();
    $userObject = $userModel->getUserById($parameters['id']);

    // use $userObject for any purpose you need
});

Now let's watch an example with all the possibilities

$router = new Router();

// First step. We have an API that talks JSON, convert the body
$router->registerMiddleware('*', function (string $route, array $parameters){
    $request = Request::createFromGlobals();

    $parameters['_request'] = $request;
    $parameters['_body'] = json_decode($request->getContent(), true);

    return $parameters;    
});

// Second step. Ensure that we are logged in when we are in the private area
$router->registerMiddleware('*', function (string $route, array $parameters){
    // Is not a private area
    if (mb_strpos($route, '/user') !== 0 || empty($parameters['user_id'])) {
        return $parameters;
    }

    $token = $parameters['_request']->headers->get('oauth_token');

    $auth = new SomeAuth();
    $auth->validateTokenOrFail(
        $token,
        $parameters['user_id']
    );

    // We don't need to return nothing
});

// Last step. Now we will modify the parameters so the handler can work with them
$router->registerMiddleware('/user/[i:user_id]', function(string $route, array $parameters){
    $userModel = new UserModel();

    return $userModel->getUserById(
        $parameters['user_id']
    );
});

// Final destination. We have ended the middlewares, now we can work with the processed data
$router->addRoute('/user/[i:user_id]', function (UserObject $userObject){
    // Do everything
});