The Laravel 5 documentation describes two ways of assigning Middleware:
However, I realised that any code written in the controllers __construct() function will run before the Middleware, even if the Middleware is declared on the first line of the controller's __construct function.
I found a bug report for a similar issue in the Laravel github repository. However a collaborator closed the issue stating "This is the expected behaviour.".
I am thinking that middleware should be "layers" outside the application, while the __construct function is part of the application.
Why is the __construct function executed before the middleware (given it is declared before middleware runs)? and why this is expected?
The application logic resides in the controller's methods. So basically application lives in the controller's methods, not in the whole controller itself.
Middleware runs BEFORE the request enters the respective controller method. And thus, this is always OUTSIDE the real application. No controller method is executed unless all the Middlewares are passing the request.
The $this->middleware("My\Middleware"); statements that you put in the controller constructor, REGISTERS the My\Middleware for checking before the request enters the application.
If you see the code of a middleware and
if the request is passing, then we send it to the next middleware using the $next($request); statement. This allows multiple middlewares to be executed for a single request. Now, if Laravel run the middleware right at the $this->middleware(...); statement, Laravel would probably not be able to know which middleware should be next checked.
So, Laravel solves this by registering all the middlewares first, then passing the request through all the middlewares one by one.