如何使用缓存 obect 将数据缓存 asp.net mvc

我在 asp.net 应用程序中使用数据缓存。这是我的ICacheProvider接口.cs

public interface ICacheProvider
{
    object Get(string key);
    void Set(string key, object data, int cacheTime);
    bool IsSet(string key);
    void Invalidate(string key);
}

这是我在服务中使用缓存的方式。

public List<EmployeeLookUp> GetEmployeeLookUp(RecordStatusEnum recordStatusEnum, int locatioId)
    {
        var status = (int)recordStatusEnum;
        var employeeData = Cache.Get("EmployeeLookUp") as IEnumerable;
        if (employeeData == null)
        {
            var result = MyDb.Employee.Where(w => w.Status == status && w.LocationId == locatioId).ToList().Select(s => new EmployeeLookUp()
            {
                EmployeeId = s.EmployeeId,
                DepartmentId = s.DepartmentId,
                EmployeeValue = string.Format("{0}{1}{2} {3} {4}", "[", s.CustomEmployeeId, "]", s.FirstName, s.LastName)
            }).ToList();
            if (result.Any())
                Cache.Set("EmployeeLookUp", result, 30);
            return result;
        }
        return (List<EmployeeLookUp>) employeeData;
    }

在控制器中，我像这样使用员工的返回。

 public ActionResult Index()
    {
        var employees = _employeeServices.GetEmployeeLookUp(RecordStatusEnum.Active, User.GetCemexUser().LocationId);
        employees.Insert(0, new EmployeeLookUp() { EmployeeId = -1, EmployeeValue = "All" });
        var complexRosterViewModel = new ComplexRosterViewModel
        {
            EmployeeList = new SelectList(employees, "EmployeeId", "EmployeeValue"),
            ListEmployeeGroups = new SelectList(_employeeGroupServices.GetEmployeeGroup(RecordStatusEnum.Active, User.GetCemexUser().LocationId), "EmployeeGroupId", "Value"),
            ListDepartments = new SelectList(_departmentService.GetDepartments(RecordStatusEnum.Active,User.GetCemexUser().LocationId),"DepartmentId","Value")
        };
        return View(complexRosterViewModel);
    }

现在我的问题是，当我多次重新加载页面时，我添加到员工选择列表中的附加"全部"选项已多次添加到缓存对象（"EmployeeLookUp"）中。这怎么可能？我不希望缓存"全部"选项。