Custom Controller Attribute to execute code before execution (C# Asp.Net Mvc)

AccessLevelAttribute.cs

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;
using System.Security.Claims;

namespace ASP.Attributes
{
    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
    public class AccessLevelAttribute : ActionFilterAttribute
    {
        private readonly int _role_level;
        public AccessLevelAttribute() { _role_level = 0; }

        public AccessLevelAttribute(int role)
        {
            _role_level = role;
        }

        public override void OnActionExecuting(ActionExecutingContext context)
        {
	    var org_Result = context.Result; //should be null but just in case
            context.Result = new UnauthorizedResult();

	    //Example using Identity to store userId (JWT)
            var identity = context.HttpContext.User.Identity as ClaimsIdentity;
            if (identity == null)
                return;
                
            var user_id = identity.FindFirst("UserId");
            if (user_id == null)
                return;

            var userRole = User.GetUser(user_id.Value).Role;
            if (userRole >= RoleLevel)
            {
                context.Result = org_Result;
                base.OnActionExecuting(context);
            }
        }

        public int RoleLevel => _role_level;
    }
}

//Don't forget to add the attr to the scope
services.AddScoped<AccessLevelAttribute>();

//Example in a controller
namespace ASP.Controller
{
    [ApiController]
    public class UserController
    {
        [HttpGet]
        [AccessLevel(7)] //check Role >= 7
        public IActionResult GetUserList()
        {
            return new JsonResult(UserManager.UserList);
        }
    }
}