observer design pattern

Author: rcsofttech85

src/Controller/ObserverDesignPattern.php

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+<?php
+
+namespace App\Controller;
+
+use App\Observable\User;
+use App\Observers\UserObserver;
+use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\Routing\Annotation\Route;
+
+class ObserverDesignPattern extends AbstractController
+{
+
+    #[Route(path: "/observerDesignPattern", name: 'observerDesignPattern', methods: ['GET'])]
+    public function welcomeUser(): Response
+    {
+        $newUser = new User();
+
+        $newUserObserver = new UserObserver();
+        $newUser->attach($newUserObserver);
+
+        $newUser->setName('rahul');
+
+            $newUser->detach($newUserObserver); // It won't notify further updates..
+
+
+        return new Response("Welcome {$newUser->getName()}!, your user id is {$newUser->getUserId()}");
+    }
+}

src/Observable/User.php

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+<?php
+
+namespace App\Observable;
+
+use SplObserver;
+
+class User implements \SplSubject
+{
+
+    private array $observers = [];
+    private string $name;
+    private string $userId;
+    public function __construct()
+    {
+    }
+
+    public function attach(SplObserver $observer): void
+    {
+        $observerId = spl_object_hash($observer);
+        $this->observers[$observerId] = $observer;
+    }
+
+    public function detach(SplObserver $observer): void
+    {
+        $observerId = spl_object_hash($observer);
+        unset($this->observers[$observerId]);
+    }
+
+    public function notify(): void
+    {
+        foreach ($this->observers as $observer) {
+            $observer->update($this);
+        }
+    }
+
+    public function setName($name) {
+        $this->name = $name;
+        $this->notify();
+    }
+
+    public function getName():string
+    {
+        return $this->name;
+    }
+
+    /**
+     * @return string
+     */
+    public function getUserId(): string
+    {
+        return $this->userId;
+    }
+
+    /**
+     * @param string $userId
+     */
+    public function setUserId(string $userId): void
+    {
+        $this->userId = $userId;
+    }
+
+}

src/Observers/UserObserver.php

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+<?php
+
+namespace App\Observers;
+
+use App\Observable\User;
+use SplSubject;
+
+class UserObserver implements \SplObserver
+{
+
+    public function update(SplSubject $subject): void
+    {
+        if (!$subject instanceof User) {
+            return;
+        }
+
+        $userId = $this->generateRandomUserID();
+
+        $subject->setUserId($userId);
+    }
+
+    private function generateRandomUserID(int $length = 8): string
+    {
+        $characters = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
+        $userID = '';
+        $charCount = strlen($characters);
+
+        for ($i = 0; $i < $length; $i++) {
+            $randomChar = $characters[random_int(0, $charCount - 1)];
+            $userID .= $randomChar;
+        }
+
+        return $userID;
+    }
+}