Route Model Binding

// Type-hint the model - Laravel resolves automatically
Route::get('/posts/{post}', function (Post $post) {
    return view('posts.show', compact('post'));
});
// Laravel executes: Post::findOrFail($routeValue)
// Returns 404 if not found - no manual handling needed

// In controllers - same magic applies
public function show(Post $post): View
{
    return view('posts.show', compact('post'));
}

// Use slug instead of id - override getRouteKeyName() in model
public function getRouteKeyName(): string
{
    return 'slug'; // Route {post} now resolves by slug column
}

// Scoped binding - child must belong to parent
// GET /users/{user}/posts/{post:slug}
Route::get('/users/{user}/posts/{post:slug}',
    function (User $user, Post $post) {
        // $post is automatically scoped: WHERE user_id = $user->id
        return view('users.posts.show', compact('user', 'post'));
    }
);
// Returns 404 if post exists but doesn't belong to this user

// Register in RouteServiceProvider (or bootstrap/app.php in Laravel 11)
Route::bind('post', function (string $value) {
    return Post::where('slug', $value)
        ->where('published', true)
        ->firstOrFail();
    // Only resolves published posts - drafts return 404
});

// Custom resolution for complex scenarios
Route::bind('invoice', function (string $value) {
    return Invoice::where('reference_number', $value)
        ->where('user_id', auth()->id())
        ->firstOrFail();
    // Users can only access their own invoices
});

// Model method alternative (cleaner)
// In Post model:
public function resolveRouteBinding($value, $field = null)
{
    return $this->where('slug', $value)
        ->where('published', true)
        ->firstOrFail();
}