Question

我在VS2010中使用Razor进行C＃项目。（MVC 4）。我需要将错误消息从Controller返回到View并显示给User。我的尝试是：

控制器：

 [HttpPost]
 public ActionResult form_edit(FormModels model)
 {          
    model.error_msg = model.update_content(model);           
    ModelState.AddModelError("error", "adfdghdghgdhgdhdgda");
    ViewBag.error = TempData["error"];
    return RedirectToAction("Form_edit", "Form");

 }

查看：

@model mvc_cs.Models.FormModels
@using ctrlr = mvc_cs.Controllers.FormController


@using (Html.BeginForm("form_edit", "Form", FormMethod.Post))
{

        <table>
        <tr>
        <td>       
        @Html.ValidationSummary("error")       
        @Html.ValidationMessage("error")      
        </td>
        </tr>
    <tr>
        <th>
            @Html.DisplayNameFor(model => model.content_name)
            @Html.DropDownListFor(x => x.selectedvalue, new SelectList(Model.Countries, Model.dd_value, Model.dd_text), "-- Select Product--")

        </th>
    </tr>
</table>

<table>
    <tr>
        <td>
            <input  type="submit" value="Submit" />
        </td>
    </tr>
</table>
}

请帮助我实现这一目标。

Answer 1

返回视图（模型）返回错误，因为您没有使用post方法中的值填充模型，并且下拉列表的模型数据为空。请提供Get方法以进一步说明如何管理显示错误。为了显示错误，您应该使用：

[HttpPost]
public ActionResult form_edit(FormModels model)
{          
   if(ModelState.IsValid())
   {
      --- operations 
      return Redirect("OtherAction", "SomeController");
   }

   // here you can use a little trick
   //fill the model property that holds the information for the dropdown with the data 

   // you haven't provided the get method but it should look something like this
   model.Countries = ... some data goes here;
   model.dd_value = ... some other data;
   model.dd_text = ... other data;

   ModelState.AddModelError("", "adfdghdghgdhgdhdgda");
   return View(model);
}

然后在视图中使用：

@model mvc_cs.Models.FormModels
@using ctrlr = mvc_cs.Controllers.FormController


@using (Html.BeginForm("form_edit", "Form", FormMethod.Post))
{

    <table>
    <tr>
    <td>       
    @Html.ValidationSummary(true)             
    </td>
    </tr>
<tr>
    <th>
        @Html.DisplayNameFor(model => model.content_name)
        @Html.DropDownListFor(x => x.selectedvalue, new SelectList(Model.Countries, Model.dd_value, Model.dd_text), "-- Select Product--")

    </th>
</tr>
</table>

<table>
<tr>
    <td>
        <input  type="submit" value="Submit" />
    </td>
</tr>
</table>
}

这应该可行。

如果您只是使用RedirectToAction，它会将您重定向到get方法 - ＆gt;您将没有错误，但视图将被重新加载，并且不会显示任何错误。

另一种方法是你不能通过ModelState.AddError传递错误，但是像这样使用ViewData [“error”]：

[HttpPost]
public ActionResult form_edit(FormModels model)
{          
   TempData["error"] = "someErrorMessage";
   return RedirectToAction("form_Post", "Form");
}

[HttpGet]
public ActionResult form_edit()
{
    do stuff here ----
    ViewData["error"] = TempData["error"];
    return View();
}

@model mvc_cs.Models.FormModels
@using ctrlr = mvc_cs.Controllers.FormController


@using (Html.BeginForm("form_edit", "Form", FormMethod.Post))
{

    <table>
    <tr>
    <td>       
    <div>@ViewData["error"]</div>             
    </td>
    </tr>
<tr>
    <th>
        @Html.DisplayNameFor(model => model.content_name)
        @Html.DropDownListFor(x => x.selectedvalue, new SelectList(Model.Countries, Model.dd_value, Model.dd_text), "-- Select Product--")

    </th>
</tr>
</table>

<table>
<tr>
    <td>
        <input  type="submit" value="Submit" />
    </td>
</tr>
</table>
}

Answer 2

感谢所有回复。

我能够通过以下方式解决这个问题：

控制器：

[HttpPost]       
public ActionResult form_edit(FormModels model)
{
  model.error_msg = model.update_content(model);
  return RedirectToAction("Form_edit", "Form", model);
}

public ActionResult form_edit(FormModels model, string searchString,string id)
{
  string test = model.selectedvalue;
  var bal = new FormModels();
  bal.Countries = bal.get_contentdetails(searchString);
  bal.selectedvalue = id;
  bal.dd_text = "content_name";
  bal.dd_value = "content_id";

  test = model.error_msg;
  ViewBag.head = "Heading";

  if (model.error_msg != null)
  {
    ModelState.AddModelError("error_msg", test);
  }

  model.error_msg = "";
  return View(bal);
}

查看：

@using (Html.BeginForm("form_edit", "Form", FormMethod.Post))
{
  <table>
    <tr>
      <td>
        @ViewBag.error
        @Html.ValidationMessage("error_msg")
      </td>
    </tr>
    <tr>
      <th>
        @Html.DisplayNameFor(model => model.content_name)
        @Html.DropDownListFor(x => x.selectedvalue, new SelectList(Model.Countries, Model.dd_value, Model.dd_text), "-- Select Product--")
      </th>
    </tr>
  </table>
}

Answer 3

如果您想进行重定向，可以：

ViewBag.Error = "error message";

或

TempData["Error"] = "error message";

Answer 4

您可以将其添加到_Layout.cshtml：

@using MyProj.ViewModels;
...
    @if (TempData["UserMessage"] != null)
    {
        var message = (MessageViewModel)TempData["UserMessage"];
        <div class="alert @message.CssClassName" role="alert">
            <button type="button" class="close" data-dismiss="alert" aria-label="Close">
                <span aria-hidden="true">&times;</span>
            </button>
            <strong>@message.Title</strong>
            @message.Message
        </div>
    }

然后，如果您想在控制器中抛出错误消息：

    TempData["UserMessage"] = new MessageViewModel() { CssClassName = "alert-danger  alert-dismissible", Title = "Error", Message = "This is an error message" };

MessageViewModel.cs：

public class MessageViewModel
    {
        public string CssClassName { get; set; }
        public string Title { get; set; }
        public string Message { get; set; }
    }

注意：使用Bootstrap 4类。

来自Controller的MVC 4-Return错误消息-Show in View

4 个答案: