Laravel 5.4: attach custom service provider to a controller - laravel-5.4

Question

I created a service provider named AdminServiceProvider
namespace App\Providers;
use Modules\Orders\Models\Orders;
use Illuminate\Support\ServiceProvider;
use View;
class AdminServiceProvider extends ServiceProvider
{
public function boot()
{
$comments = Orders::get_new_comments();
View::share('comments', $comments);
}
public function register()
{
}
}
Registered the provider
App\Providers\AdminServiceProvider::class,
Now I try to attach it to the controller
namespace App\Http\Controllers\admin;
use Illuminate\Http\Request;
use App\Http\Controllers\Controller;
use App\Providers\AdminServiceProvider;
class AdminController extends Controller
{
public $lang;
public function __construct()
{
}
public function index(){
return view('admin/dashboard');
}
}
Now I get this error message
Undefined variable: comments
This is the first time I try to use a custom service provider and don't know exactly how it works I'm sure there's something missing Hope you can help. Thanks in advance.
[UPDATE]
removed use App\Providers\AdminServiceProvider; from the controller
php artisan clear-compiled solved the problem but I want to attach it to some controllers not all controllers as the $comments are sent to all contollers in my app. So how to attach the service provider to specific controllers not all of them?

Answer 1

For the undefined variable run: php artisan clear-compiled will solve it
If you want to share a variable in some of your views you can create a middleware and assign it to the views you want to share the data with:
First create a middleware: php artisan make:middleware someName
Then in the handle function you add your view sharing logic:
$comments = Orders::get_new_comments();
view()->share('comments',$comments);
return $next($request);
Then register your middleware under the $routeMiddleware array and
give it an alias.
Then attach it to your routes like:
Route::group(['middleware'=> 'yourMiddlewwareName'], function(){
//your routes
});

Answer 2

If you have all your admin views in one directory (views\admin for example) you can use view composer in AdminServiceProvider:
public function boot()
{
view()->composer('admin.*', function($view){
$view->with('comments', Orders::get_new_comments());
});
}
It will attach comments variable to each view in your views\admin directory.
You can also attach a variable to some specific views or folders like this:
view()->composer(['admin.posts.*', 'admin.pages.index'], function($view){
$view->with('comments', Orders::get_new_comments());
});