codebar-ag/observers

Observers

When to Use

• A side effect must run on every model lifecycle mutation, regardless of call site.
• The behavior is model-centric (cache invalidation, audit trail, lightweight notifications).
• Multiple code paths mutate the same model and should trigger consistent reactions.

When Not to Use

• Side effects should run only in one explicit workflow (use an Action).
• You need precise control over exactly when logic runs in a business transaction.
• The logic is complex orchestration (use a Service/Event pipeline).

Rules

• Observer classes live in app/Observers/
• Naming: PascalCase with an Observer suffix, named after the model they observe: UserObserver, InvoiceObserver
• Only define the event methods you actually need — do not scaffold empty methods
• Register observers in AppServiceProvider using the observe() method
• Use observers for side effects tied to model lifecycle events that should always fire
• Never put business logic that should be explicitly controlled in an observer — use an Action instead

Examples

namespace App\Observers;

use App\Models\User;
use App\Notifications\WelcomeNotification;
use Illuminate\Support\Facades\Cache;

class UserObserver
{
    public function created(User $user): void
    {
        $user->notify(new WelcomeNotification());
    }

    public function updated(User $user): void
    {
        Cache::forget("user:{$user->id}");
    }

    public function deleted(User $user): void
    {
        Cache::forget("user:{$user->id}");
    }
}

// Registration in AppServiceProvider
use App\Models\User;
use App\Observers\UserObserver;

public function boot(): void
{
    User::observe(UserObserver::class);
}

// Anti-pattern: observer used where explicit Action flow is required
class InvoiceObserver
{
    public function updated(Invoice $invoice): void
    {
        if ($invoice->status === 'paid') {
            app(SendPaidInvoiceEmail::class)->execute($invoice);
        }
    }
}

// Better: explicit flow in Action for predictable control
class MarkInvoicePaid
{
    public function execute(Invoice $invoice): void
    {
        $invoice->update(['status' => 'paid']);
        app(SendPaidInvoiceEmail::class)->execute($invoice);
    }
}

Available lifecycle events:

| Method | Fires when... | |---|---| | creating | Before a model is first saved | | created | After a model is first saved | | updating | Before an existing model is saved | | updated | After an existing model is saved | | saving | Before creating or updating | | saved | After creating or updating | | deleting | Before a model is deleted | | deleted | After a model is deleted | | restoring | Before a soft-deleted model is restored | | restored | After a soft-deleted model is restored |

creating, updating, saving, deleting, and restoring run before persistence and may cancel the operation by returning false when needed.

Anti-Patterns

• Using an observer for side effects specific to one particular action (use the Action directly instead)
• Scaffolding empty observer methods for all lifecycle events when only one is needed
• Putting complex orchestration inside an observer (use a Service)
• Using an observer for validation (use Form Requests)
• Using an observer for authorization (use Policies)
• Relying on observers when you need fine-grained control over when side effects fire

References

• Laravel Observers
• Laravel Model Events
• Related: Models/SKILL.md — Eloquent model conventions
• Related: Events/SKILL.md — alternative for decoupled side effects