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

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.我被尝试的是:

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");

 }

视图:

@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>
}

请帮我实现这个目标.

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>
}

这应该没问题.

如果您只使用RedirectToAction,它会将您重定向到get方法 - >您将没有错误,但视图将被重新加载并且不会显示错误.

另一种方法是你不能通过ModelState.AddError传递错误,但是使用ViewData ["error"],如下所示:

[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

感谢所有的答复.

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);
}   

视图:

@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>
}