如何在ViewBag（）的帮助下填充下拉列表？ [英] How to populate the Drop Down List with the help of ViewBag()?

问题描述

你好，



我不知道我的代码有什么问题。以下是代码类，并获取错误 ArgumentNullException ：



我正在使用数据库第一种方法。



这是我的模型类：

Hello,

I do not know what is wrong in my code. following are the code classes respectively, and getting the error ArgumentNullException :

I am using the DB first approach.

Here is my model class:

public partial class Employee
    {
        public int EmployeeID { get; set; }
        public Nullable<int> EmployeeTypeID { get; set; }
        public int DepartmentID { get; set; }
        public int GradeID { get; set; }

        public virtual ICollection<BillingLinkedPersonnel> BillingLinkedPersonnels { get; set; }
        public virtual Department Department { get; set; }
        public virtual EmployeeType EmployeeType { get; set; }
        public virtual ICollection<EmployeeDetail> EmployeeDetails { get; set; }
        public virtual ICollection<EmployeeEducationDetail> EmployeeEducationDetails { get; set; }
        public virtual ICollection<EmployeeLeave> EmployeeLeaves { get; set; }
        public virtual Grade Grade { get; set; }
    }

现在这是我的控制器类 ViewBag 对象方法：

Now here is my controller class ViewBag object method:

ViewBag.EmployeeTypeName = from EmployeeType in employee.EmployeeType.Name select new SelectListItem() { Text = employee.EmployeeType.Name, Value = employee.EmployeeType.EmployeeTypeID.ToString()};

现在这里是我的视图 DropDownListFor（）：

Now here is my view DropDownListFor():

@Html.DropDownListFor(m => m.EmployeeType.Name,(IEnumerable<SelectListItem>)ViewBag.EmployeeTypeName, "select city")

任何人都可以告诉我这有什么问题吗？



谢谢

Can any one tell me what is wrong with this?

Thanks

推荐答案

再看一个条件

see with one more condition

@if(ViewBag.EmployeeTypeName !=null){
@Html.DropDownListFor(m => m.EmployeeType.Name,(IEnumerable<SelectListItem>)ViewBag.EmployeeTypeName, "select city") 
}

使用ToList（）对于viewbag对象，因为它需要可枚举的列表

make a to use ToList() for viewbag object because it needs enumerable list

                    ViewBag.EmployeeTypeName = new SelectList(employee.EmployeeType.ToList(), "EmployeeTypeID", "Name", "EmployeeTypeID");
;

Controller`s Create（）

Controller`s Create()

List<SelectListItem> employeeListItems = new List<SelectListItem>();
           foreach (var item in _entities.Employees.ToList())
           {
               employeeListItems.Add(new SelectListItem() { Text = item.FirstName + " " + item.LastName, Value = item.EmployeeID.ToString() });
           }
           ViewBag.EmployeeList = employeeListItems;

比视图

Than the in the view

@Html.DropDownListFor(model => model.EmployeeID, (IEnumerable<SelectListItem>)ViewBag.EmployeeList })

感谢Sankarsan先生帮助最高级别。

Thank you Sankarsan Sir for helping at an highest level.

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