Question

我目前正在从事这项任务。除非我从另一个表中放入一个下拉列表，否则一切正常。我需要在我的数据库中插入一行，但我遇到了一个错误

System.ArgumentNullException: 'Value cannot be null.
Parameter name: items'

我已经找到了我在网上找到的解决方案，但出于某些原因它并不适用于我的问题。

控制器：

[HttpGet]
    public ActionResult Add()
    {
        try
        {
            ViewBag.Departments = db.Departments.ToList();
            return View();
        }
        catch (Exception genericException) 
        {
            ViewBag.ExceptionMessage = genericException.Message;
        }
        return View("~/Views/Errors/Details.cshtml");
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Add(Volunteer volunteer)
    {
        try
        {
            if (ModelState.IsValid)
            {
                db.Volunteers.Add(volunteer);
                db.SaveChanges();
                return RedirectToAction("Index");
            }
            ViewBag.Department = db.Departments.ToList();
            return View(volunteer);
        }
        catch (DbUpdateException DbException)
        {
            ViewBag.DbExceptionMessage = DbException.Message;
        }
        catch (Exception genericException)
        {
            ViewBag.ExceptionMessage = genericException;
        }
        return View("~/Views/Errors/Details.cshtml");
    }

查看：

@model Features.Models.Volunteer
@{
ViewBag.Title = "Add";
Layout = "~/Views/Shared/_Layout.cshtml";
}

<h2>Add a volunteer</h2>

@using (Html.BeginForm("Add", "Volunteer"))
{
@Html.AntiForgeryToken()

<div>
    <div>
        @Html.LabelFor(v => v.Department)

        @Html.DropDownListFor(v => v.Department, new SelectList(ViewBag.Department, "DepartmentName", "DepartmentName"), "-")
        @Html.ValidationMessageFor(v => v.Department)
    </div>
</div>
<input type="submit" value="Create" />

是的，有人能帮帮我吗？谢谢。

ASP.NET MVC：System.ArgumentNullException：＆＃39;值不能为null。参数名称：items＆＃39;

0 个答案: