ASP.NET MVC模型绑定

我遇到了模型绑定的问题。如果我做在CopyToModelStateDictionary方法中使用前缀，我没有得到无效控件的样式或验证消息。如果我不要使用前缀，我会得到造型和验证消息，但如果用户没有从动态创建的单选按钮列表中进行选择，页面就会崩溃。我怎么能得到这两个？我不明白这里发生了什么。ASP.NET MVC模型绑定

[AcceptVerbs(HttpVerbs.Post)] 
    public ActionResult Edit(int id, FormCollection collection) 
    { 
     Request request = requestRepository.GetById(id); 
     UpdateModel(request); 
     Helpers.CopyToModelStateDictionary(request.GetRuleViolations(), ModelState, "request"); 
     ... 
     if (!ModelState.IsValid) 
     { 
      return View("Edit_Requestor", request); 
     } 
    } 

    public static void CopyToModelStateDictionary(NameValueCollection errors, ModelStateDictionary modelState, string prefix) 
    { 
     foreach (string key in errors) 
     { 
      foreach (string value in errors.GetValues(key)) 
      { 
       modelState.AddModelError(prefix + "." + key, value); 
      } 
     } 
    }

错误消息

Line 9: foreach (ProblemType problemType in problemTypes) 
Line 10: { 
Line 11:  Writer.Write(Html.RadioButton("ProblemType", problemType.Value)); 
Line 12:  Writer.Write(problemType.Text + "<br/>"); 
Line 13: }

堆栈跟踪：

[NullReferenceException: Object reference not set to an instance of an object.] 
System.Web.Mvc.HtmlHelper.GetModelStateValue(String key, Type destinationType) +63 
System.Web.Mvc.Html.InputExtensions.InputHelper(HtmlHelper htmlHelper, InputType inputType, String name, Object value, Boolean useViewData, Boolean isChecked, Boolean setId, Boolean isExplicitValue, IDictionary`2 htmlAttributes) +328 
System.Web.Mvc.Html.InputExtensions.RadioButton(HtmlHelper htmlHelper, String name, Object value, Boolean isChecked, IDictionary`2 htmlAttributes) +193 
System.Web.Mvc.Html.InputExtensions.RadioButton(HtmlHelper htmlHelper, String name, Object value, IDictionary`2 htmlAttributes) +282 
System.Web.Mvc.Html.InputExtensions.RadioButton(HtmlHelper htmlHelper, String name, Object value) +61 
ASP.views_request_lstproblemtype_ascx.__Render__control1(HtmlTextWriter __w, Control parameterContainer) in c:\Web\Views\Request\lstProblemType.ascx:11 
System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +256 
System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +19 
System.Web.UI.Control.Render(HtmlTextWriter writer) +10 
System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27 
System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +99 
System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25 
System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +134 
System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +19 
System.Web.UI.Page.Render(HtmlTextWriter writer) +29 
System.Web.Mvc.ViewPage.Render(HtmlTextWriter writer) +59 
System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27 
System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +99 
System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25 
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1266

感谢您阅读我的问题！

来源

2009-06-17 Leslie