add data from work folder

07-dispatching-to-a-class.md

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+
+### Dispatching to a Class
+
+In this tutorial we won't implement [MVC (Model-View-Controller)](http://martinfowler.com/eaaCatalog/modelViewController.html). 
+MVC can't be implemented properly in PHP anyway, at least not in the way it was originally conceived. If you want to
+learn more about this, read [A Beginner's Guide To MVC](http://blog.ircmaxell.com/2014/11/a-beginners-guide-to-mvc-for-web.html)
+and the followup posts.
+
+So forget about MVC and instead let's worry about [separation of concerns](http://en.wikipedia.org/wiki/Separation_of_concerns).
+
+We will need a descriptive name for the classes that handle the requests. For this tutorial I will use `Handler`, other
+common names are 'Controllers' or 'Actions'.
+
+Create a new folder inside the `src/` folder with the name `Handler`.In this folder we will place all our action classes.
+In there, create a `Hello.php` file.
+
+```php
+<?php declare(strict_types = 1);
+
+namespace Lubian\NoFramework\Action;
+
+final class Hello implements \Psr\Http\Server\RequestHandlerInterface
+{
+    public function handle(\Psr\Http\Message\ServerRequestInterface $request): \Psr\Http\Message\ResponseInterface
+    {
+        $name = $request->getAttribute('name', 'Stranger');
+        $response = (new \Laminas\Diactoros\Response)->withStatus(200);
+        $response->getBody()->write('Hello ' . $name . '!');
+        return $response;
+    }
+}
+```
+
+You can see that we implement the [RequestHandlerInterface](https://github.com/php-fig/http-server-handler/blob/master/src/RequestHandlerInterface.php)
+that has a 'handle'-Method with requires a Requestobject as its parameter and returns a Responseobject. For now this is
+fine, but we may have to change our approach later. In anyway it is good to know about this interface as we will implement
+it in some other parts of our application as well. In order to use that Interface we have to require it with composer:
+'composer require psr/http-server-handler'.
+
+The autoloader will only work if the namespace of a class matches the file path and the file name equals the class name. 
+At the beginning I defined `Lubian\NoFramework` as the root namespace of the application so this is referring to the `src/` folder.
+
+Now let's change the hello world route so that it calls your new class method instead of the closure. Change your `routes.php` to this:
+
+```php
+return function(\FastRoute\RouteCollector $r) {
+    $r->addRoute('GET', '/hello[/{name}]', \Lubian\NoFramework\Action\Hello::class);
+    $r->addRoute('GET', '/another-route', \Lubian\NoFramework\Action\Another::class);
+};
+```
+
+Instead of a callable we are now passing the fully namespaced class identifier to the route-definition. I also declared
+the class 'Another' as the target for the second route, you can create it by copying the Hello.php file and changing
+the response to the one we defined for the second route.
+
+To make this work, you will also have to do a small refactor to the routing part of the `Bootstrap.php`:
+
+```php
+case \FastRoute\Dispatcher::FOUND:
+     $handler = new $routeInfo[1];
+     if (! $handler instanceof \Psr\Http\Server\RequestHandlerInterface) {
+        throw new \Exception('Invalid Requesthandler');
+     }
+     foreach ($routeInfo[2] as $attributeName => $attributeValue) {
+        $request = $request->withAttribute($attributeName, $attributeValue);
+     }
+    $response = $handler->handle($request);
+    assert($response instanceof \Psr\Http\Message\ResponseInterface)
+    break;
+```
+
+So instead of just calling a method you are now instantiating an object and then calling the method on it.
+
+Now if you visit `http://localhost:1234/` everything should work. If not, go back and debug.
+
+And of course don't forget to commit your changes.
+
+Something that still bothers me is the fact, that we do have classes for our Handlers, but the Error responses are still
+generated in the routing-matching section and not in special classes. Also we have still left some cases to chance, for
+example if there is an error in creating our RequestHandler class or if the call to the 'handle' function fails. We still
+have our whoopsie error-handler but i like to be more explicit in my control flow.
+
+In order to do that we need to define some special Exceptions that we can throw and catch explicitly. Lets add a new
+Folder/Namespace to our src directory called Exceptions. And define the classes NotFound, MethodNotAllowed and
+InternalServerError. All three should extend phps Base Exception class.
+
+Here is my NotFound.php for example.
+
+```php
+<?php
+
+declare(strict_types=1);
+
+namespace Lubian\NoFramework\Exception;
+
+final class NotFound extends Exception{}
+```
+
+Use that example to create a MethodNotAllowedException.php and InternalServerErrorException.php as well.
+
+After you have created those we update our Routercode to use the new Exceptions.
+
+```php
+try {
+    switch ($routeInfo[0]) {
+        case Dispatcher::FOUND:
+            $className = $routeInfo[1];
+            $handler = new $className;
+            assert($handler instanceof RequestHandlerInterface);
+            foreach ($routeInfo[2] as $attributeName => $attributeValue) {
+                $request = $request->withAttribute($attributeName, $attributeValue);
+            }
+            $response = $handler->handle($request);
+            break;
+        case Dispatcher::METHOD_NOT_ALLOWED:
+            throw new MethodNotAllowed;
+
+        case Dispatcher::NOT_FOUND:
+        default:
+            throw new NotFound;
+    }
+} catch (MethodNotAllowed) {
+    $response = (new Response)->withStatus(405);
+    $response->getBody()->write('Not Allowed');
+} catch (NotFound) {
+    $response = (new Response)->withStatus(404);
+    $response->getBody()->write('Not Found');
+} catch (Throwable $t) {
+    throw new InternalServerError($t->getMessage(), $t->getCode(), $t);
+}
+```
+
+Check if our code still works, try to trigger some errors, run phpstan and the fix command
+and don't forget to commit your changes.
+
+[<< previous](06-router.md) | [next >>](08-inversion-of-control.md)