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ASP。NET MVC模型绑定

model-binding asp.net-mvc c#

Les · 技术社区 · 17 年前

我在模型绑定方面遇到了问题。如果我做使用CopyToModelStateDictionary方法中的前缀,我无法获得无效控件的样式或验证消息。如果我

    [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);
            }
        }
    }

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

1 回复 | 直到 17 年前

Community Mohan Dere 9 年前

这可能会有所帮助。

您正在添加一个模态错误,因此MVC正在尝试检索尝试的值,但由于您没有添加它,它失败了。

Validating form using ModelState

ASP.NET MVC - Html.Textbox() throws "Object reference not set to an instance of an object"