Automating Logic with Eloquent Model Events and Observers

// --- Method 1: Using Model Events (within the Model) ---
// app/Models/User.php
namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Support\Str;

class User extends Model
{
    protected static function boot()
    {
        parent::boot();

        // Automatically generate a UUID for new users
        static::creating(function ($user) {
            if (empty($user->uuid)) {
                $user->uuid = (string) Str::uuid();
            }
        });

        // Log whenever a user is updated
        static::updating(function ($user) {
            \Log::info("User {$user->id} updated. New email: {$user->email}");
        });

        // Perform actions after a user is deleted
        static::deleted(function ($user) {
            // For example, delete related files or clear cache
            \Cache::forget('user_profile_' . $user->id);
            \Log::info("User {$user->id} and related cache cleared.");
        });
    }
}

// --- Method 2: Using an Eloquent Observer (for cleaner separation) ---
// 1. Create the Observer: php artisan make:observer UserObserver --model=User
// app/Observers/UserObserver.php
namespace App\Observers;

use App\Models\User;

class UserObserver
{
    /**
     * Handle the User "created" event.
     *
     * @param  \App\Models\User  $user
     * @return void
     */
    public function created(User $user)
    {
        // Send welcome email, assign default role, etc.
        \Mail::to($user->email)->send(new \App\Mail\WelcomeEmail($user));
        $user->assignRole('default');
    }

    /**
     * Handle the User "updated" event.
     *
     * @param  \App\Models\User  $user
     * @return void
     */
    public function updated(User $user)
    {
        // Record changes in an audit log
        \AuditLog::create([
            'user_id' => $user->id,
            'action' => 'updated',
            'details' => json_encode($user->getDirty()),
        ]);
    }

    // You can define methods for retrieved, creating, updating, saving,
    // deleting, restoring, forceDeleting
}

// 2. Register the Observer (in App\Providers\AppServiceProvider.php's boot method)
// use App\Models\User;
// use App\Observers\UserObserver;
// ...
// public function boot()
// {
//     User::observe(UserObserver::class);
// }