🧠 1. Cache কী এবং কেন ব্যবহার করবো?

Cache হলো এমন একটা system যেখানে database থেকে বারবার data না এনে memory থেকে দ্রুত data আনা হয়।

👉 এতে performance অনেক বেড়ে যায়

⚡ 2. Cache::rememberForever (Basic Usage)

use Illuminate\Support\Facades\Cache;
use App\Models\Product;

$products = Cache::rememberForever('active_products', function () {
    return Product::with('category')->where('active', 1)->get();
});

🧠 এটা কী করে?

প্রথমবার DB থেকে data নেয়
পরে cache থেকে data দেয়
manual clear না করলে forever থাকে

⚠️ Problem

Product update হলে cache update হয় না ❌

🚀 3. Trait তৈরি করা (Reusable Cache Clear)

📍 app/Traits/ClearsCache.php

namespace App\Traits;

use Illuminate\Support\Facades\Cache;

trait ClearsCache
{
    protected function clearCache(string $key): void
    {
        Cache::forget($key);
    }
}

🧩 4. Observer (Automatic Cache Clear)

📍 Create observer:

php artisan make:observer ProductObserver --model=Product

✍️ Observer code:

namespace App\Observers;

use App\Models\Product;
use App\Traits\ClearsCache;
use App\Events\ProductUpdated;

class ProductObserver
{
    use ClearsCache;

    protected function clearAll(): void
    {
        $this->clearCache('active_products');
    }

    public function created(Product $product)
    {
        $this->clearAll();
        event(new ProductUpdated());
    }

    public function updated(Product $product)
    {
        $this->clearAll();
        event(new ProductUpdated());
    }

    public function deleted(Product $product)
    {
        $this->clearAll();
        event(new ProductUpdated());
    }
}

🔗 Register Observer

📍 AppServiceProvider.php

use App\Models\Product;
use App\Observers\ProductObserver;

public function boot(): void
{
    Product::observe(ProductObserver::class);
}

🚀 5. Filament Cache Usage

use Illuminate\Support\Facades\Cache;
use App\Models\Product;

public static function getEloquentQuery()
{
    return Cache::rememberForever('active_products', function () {
        return Product::with('category')->where('active', 1);
    });
}

⚡ 6. Livewire Event Listener (UI Auto Refresh)

📍 ListProducts.php

protected $listeners = ['productUpdated' => '$refresh'];

🧩 Bridge Event

use Illuminate\Support\Facades\Event;
use App\Events\ProductUpdated;

public function mount(): void
{
    parent::mount();

    Event::listen(ProductUpdated::class, function () {
        $this->dispatch('productUpdated');
    });
}

🔄 FINAL FLOW

Admin updates product
        ↓
Observer runs
        ↓
Cache cleared
        ↓
Event fired
        ↓
Livewire catches event
        ↓
UI refresh ($refresh)
        ↓
User sees updated data

🎯 Best Practices

✅ Cache naming

Good:

active_products
active_products_with_category

Bad:

data1
temp

✅ Always clear cache on mutation

create
update
delete

✅ Use Observer (not controller)

✔ clean
✔ scalable

🏁 Final Summary

Cache = speed ⚡

Observer = freshness 🔄

Trait = reuse ♻️

Event = communication 📡

Livewire = UI update 🎯

"Cache speeds up reading, Observer keeps it fresh, Livewire updates UI"

How to Use Cache in FilamentPHP (Beginner Guide + Best Practices)