在我的控制器操作中,我有以下代码:
public ActionResult GridAction(string id)
{
if (String.IsNullOrEmpty(id))
{
// add errors to the errors collection and then return the view saying that you cannot select the dropdownlist value with the "Please Select" option
}
return View();
}
更新:
if (String.IsNullOrEmpty(id))
{
// add error
ModelState.AddModelError("GridActionDropDownList", "Please select an option");
return RedirectToAction("Orders");
}
更新2:
这是我更新的代码:
@Html.DropDownListFor(x => x.SelectedGridAction, Model.GridActions,"Please Select")
@Html.ValidationMessageFor(x => x.SelectedGridAction)
模型如下所示:
public class MyInvoicesViewModel
{
private List<SelectListItem> _gridActions;
public int CurrentGridAction { get; set; }
[Required(ErrorMessage = "Please select an option")]
public string SelectedGridAction { get; set; }
public List<SelectListItem> GridActions
{
get
{
_gridActions = new List<SelectListItem>();
_gridActions.Add(new SelectListItem() { Text = "Export to Excel", Value = "1" });
return _gridActions;
}
}
}
这是我的控制器动作:
public ActionResult GridAction(string id)
{
if (String.IsNullOrEmpty(id))
{
// add error
ModelState.AddModelError("SelectedGridAction", "Please select an option");
return RedirectToAction("Orders");
}
return View();
}
什么都没发生!我完全迷失在这一个!
更新3:
我现在正在使用以下代码,但仍未验证验证:
public ActionResult GridAction(string id)
{
var myViewModel= new MyViewModel();
myViewModel.SelectedGridAction = id; // id is passed as null
if (!ModelState.IsValid)
{
return View("Orders");
}
更新4:
$("#linkGridAction").click(function () {
alert('link grid action clicked');
$.get('GridAction/', { SelectedGridAction: $("#SelectedGridAction").val() }, function (result) {
alert('success');
});
});
控制器如下所示:
// OrderViewModel has a property called SelectedGridAction.
public ActionResult GridAction(OrderViewModel orderViewModel)
{
return View();
}
更新5:验证未触发:
public ActionResult GridAction(OrderViewModel orderViewModel)
{
if (!ModelState.IsValid)
{
return View("Orders", orderViewModel);
}
return View();
}
答案 0 :(得分:55)
使用ModelState.AddModelError()
ModelState.AddModelError("MyDropDownListKey", "Please Select");
并输出到视图中:
<%= Html.ValidationMessage("MyDropDownListKey") %>
答案 1 :(得分:6)
您可以使用视图模型:
public class MyViewModel
{
[Required]
public string Id { get; set; }
}
然后:
public ActionResult GridAction(MyViewModel model)
{
if (ModelState.IsValid)
{
// the model is valid, the user has selected an id => use it
return RedirectToAction("Success");
}
return View();
}
更新:
在对我的回答发表数百条评论之后,我觉得有必要提供一个完整的工作示例:
像往常一样从视图模型开始:
public class MyViewModel
{
[Required]
public string SelectedItemId { get; set; }
public IEnumerable<SelectListItem> Items
{
get
{
// Dummy data
return new SelectList(Enumerable.Range(1, 10)
.Select(i => new SelectListItem
{
Value = i.ToString(),
Text = "item " + i
}),
"Value", "Text");
}
}
}
然后是控制器:
public class HomeController: Controller
{
public ActionResult Index()
{
return View(new MyViewModel());
}
[HttpPost]
public ActionResult Index(MyViewModel model)
{
if (!ModelState.IsValid)
{
// The user didn't select any value => redisplay the form
return View(model);
}
// TODO: do something with model.SelectedItemId
return RedirectToAction("Success");
}
}
最后是观点:
<% using (Html.BeginForm()) { %>
<%= Html.DropDownListFor(
x => x.SelectedItemId,
Model.Items,
"-- Select Item --"
) %>
<%= Html.ValidationMessageFor(x => x.SelectedItemId) %>
<input type="submit" value="OK" />
<% } %>
答案 2 :(得分:0)
关于你的更新#3,我怀疑那是因为你实际上是在分配值,它只是一个空字符串(必需检查为null)。
你想要这样做:
[Required(AllowEmptyStrings = false)]
您最好的选择是执行自定义验证(您可能希望验证密钥是否在列表中等)
编辑:修复了代码中的拼写错误 - 忘了关闭“)”