What is a controller in laravel?

Example # 1: defining and implementing a route within one method call (in the web.php routes file)

// inside routes / web.php
<? php
Route :: get ('/ hello-world', function (Request $ request) {
   $ name = $ request-> name;
   return response () -> make ("<h1> Hello World! This is". $ name, 200);
});

Example # 2. The route definition is in route / web.php, but its implementation is in the class / app / Http / Controllers / HelloWorldController

// inside routes / web.php
<? php

Route :: get ('/ hello-world', 'HelloWorldController @ index') -> name ('hello-world');

-------------------------------------------------- ----------------------------------
// inside app / Http / Controllers / HelloWorldController.php
<? php
namespace App \ Http \ Controllers;
use Illuminate \ Http \ Request;

class HelloWorldController extends Controller
{
   public function index (Request $ request)
   {
       $ name = $ request-> name;
       return response () -> make ("<h1> Hello World! This is". $ name, 200);
   }
}

While example # 2 looks much more time consuming (and it isn’t – just a little more code – that’s it), let’s take a look at the benefits we get by instead placing our action logic for a given “hello-world” route inside a controller from the route definition into as a callback function:

1. Our logic is clearly divided into a class of its own (separation of interests)
2. Our controller will be configured to extend later if we need to add more functionality to it … Let’s say maybe we want to add a goodbye function … In this case, we’ll rename the controller to the more generic “HelloController” then define two separate methods, hello () and goodbye () . We would also need to define two separate routes that map the / hello and / goodbye URIs to their respective methods on the controller. This is desirable compared to populating a routes file with the implementation of each route defined as a callback function.
3. Laravel has a built-in ability to cache all route definitions in an application to speed up the time it takes to find a given route (increases application performance); however, you will only be able to take advantage of this if all the routes you define within the application are configured using controller-specific bindings (see example # 2 above)

Let’s run this command, which will generate a new controller for us.

// ... inside the project's root directory:
php artisan make: controller UploadController   

Basically, this command generates a stub for a controller named “UploadController” inside the main controller directory at /app/Http/Controllers/UploadController.php. Feel free to open this file and see. This is very easy because it is only a mocked version of the controller with the correct namespace path and the required classes from which it extends.