HTML Helper未在ASP.Net MVC3中检测模型

Question

在我当前的项目中，我必须在ASP.Net MVC3 Razor中实现从数据库动态加载树菜单。以下结构显示了我的菜单模型。 MVC3的专业水平：初学者

MenuId名称ParentMenuId OrderBy

1项目1空1 2项目2空2 3项目2.1
2 1 4项目2.1.1 3 1 5项目2.1.2 3 2

为此，我已经做了以下事情：1.Created Htmlhelper包含菜单和子菜单的静态类，2.Created Menu的模型，3.将HtmlHelper命名空间添加到views / web.config

当我们调试代码时，它显示了一个错误，即值不能为null。但是我的数据库包含数据，即count = 11该错误是由于菜单计数为零而导致的。由于菜单表包含11行数据，该如何解决？

错误

值不能为空。 参数名称：来源

说明：执行当前Web请求期间发生未处理的异常。 请查看堆栈跟踪，以获取有关错误及其在代码中起源的更多信息。

异常详细信息：System.ArgumentNullException：值不能为null。 参数名称：来源

源错误：

第14行：{第15行：string htmloutput = string.Empty; 第16行：如果（menu.Count（）> 0），则第17行：{第18行：htmloutput + =“”;

源文件：D：\\ VS Projects \\ Elixir \\ Elixir \\ HtmlHelpers \\ HtmlHelperExtensions.cs行：16

堆栈跟踪：

[ArgumentNullException：值不能为null。 参数名称：source] System.Linq.Enumerable.Count（IEnumerable 1 source) +4164811
Elixir.HtmlHelpers.HtmlHelperExtensions.ParentMenus(HtmlHelper html, IEnumerable 1 source) +4164811
Elixir.HtmlHelpers.HtmlHelperExtensions.ParentMenus(HtmlHelper html, IEnumerable D：\\ VS Projects \\ Elixir \\ Elixir \\ HtmlHelpers \\ HtmlHelperExtensions.cs：16中的1 source) +4164811
Elixir.HtmlHelpers.HtmlHelperExtensions.ParentMenus(HtmlHelper html, IEnumerable 1菜单）
d：\\ VS Projects \\ Elixir \\ Elixir \\ Views \\ Home \\ Menus.cshtml：4中的ASP._Page_Views_Home_Menus_cshtml.Execute（）
System.Web.WebPages.WebPageBase.ExecutePageHierarchy（）+207
System.Web.Mvc.WebViewPage.ExecutePageHierarchy（）+81
System.Web.WebPages.WebPageBase.ExecutePageHierarchy（WebPageContext pageContext，TextWriter writer，WebPageRenderingBase startPage）+88
System.Web.Mvc.RazorView.RenderView（ViewContext viewContext，TextWriter编写器，对象实例）+220
System.Web.Mvc.BuildManagerCompiledView.Render（ViewContext viewContext，TextWriter writer）+115
System.Web.Mvc.HtmlHelper.RenderPartialInternal（字符串局部视图名，ViewDataDictionary viewData，对象模型，TextWriter作家，ViewEngineCollection viewEngineCollection）+279
System.Web.Mvc.Html.PartialExtensions.Partial（HtmlHelper htmlHelper，字符串partialViewName，对象模型，ViewDataDictionary viewData）+113 System.Web.Mvc.Html.PartialExtensions.Partial（HtmlHelper htmlHelper，字符串partialViewName）+31
d：\\ VS Projects \\ Elixir \\ Elixir \\ Views \\ Home \\ Index.cshtml：16中的 ASP._Page_Views_Home_Index_cshtml.b_ 2（）
System.Web.WebPages。<> c _DisplayClassb.b__9（TextWriter tw）+283 System.Web.WebPages.HelperResult.WriteTo（TextWriter writer）+12 System.Web.WebPages.WebPageBase.Write（HelperResult结果）+67 ASP。 d：\\ VS Projects \\ Elixir \\ Elixir \\ Views \\ Shared_LayoutUser.cshtml：136中的_Page_Views_Shared__LayoutUser_cshtml.Execute（）
System.Web.WebPages.WebPageBase.ExecutePageHierarchy（）+207
System.Web.Mvc.WebViewPage.ExecutePageHierarchy（）+81
System.Web.WebPages.WebPageBase.ExecutePageHierarchy（WebPageContext pageContext，TextWriter writer，WebPageRenderingBase startPage）+88
System.Web.WebPages。<> c_ DisplayClass7.b _6（TextWriter writer）+102 System.Web.WebPages.HelperResult.WriteTo（TextWriter writer）+12 System.Web.WebPages.WebPageBase.Write（HelperResult结果）+67
System.Web.WebPages.WebPageBase.RenderSurrounding（字符串partialViewName，动作1 body) +66
System.Web.WebPages.WebPageBase.PopContext() +262
System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +95
System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +220
System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +115
System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +303 System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +13
System.Web.Mvc.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19() +23 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func 1 body) +66
System.Web.WebPages.WebPageBase.PopContext() +262
System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +95
System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +220
System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +115
System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +303 System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +13
System.Web.Mvc.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19() +23 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func 1 body) +66
System.Web.WebPages.WebPageBase.PopContext() +262
System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +95
System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +220
System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +115
System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +303 System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +13
System.Web.Mvc.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19() +23 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func 1延续）+260
System.Web.Mvc。<> c_ DisplayClass1e.b _1b（）+19 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters（ControllerContext controllerContext，IList 1 filters, ActionResult actionResult) +177
System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +343
System.Web.Mvc.Controller.ExecuteCore() +116
System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +97 System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +10
System.Web.Mvc.<>c__DisplayClassb.<BeginProcessRequest>b__5() +37
System.Web.Mvc.Async.<>c__DisplayClass1.<MakeVoidDelegate>b__0() +21
System.Web.Mvc.Async.<>c__DisplayClass8 1 filters, ActionResult actionResult) +177
System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +343
System.Web.Mvc.Controller.ExecuteCore() +116
System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +97 System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +10
System.Web.Mvc.<>c__DisplayClassb.<BeginProcessRequest>b__5() +37
System.Web.Mvc.Async.<>c__DisplayClass1.<MakeVoidDelegate>b__0() +21
System.Web.Mvc.Async.<>c__DisplayClass8 1 filters, ActionResult actionResult) +177
System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +343
System.Web.Mvc.Controller.ExecuteCore() +116
System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +97 System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +10
System.Web.Mvc.<>c__DisplayClassb.<BeginProcessRequest>b__5() +37
System.Web.Mvc.Async.<>c__DisplayClass1.<MakeVoidDelegate>b__0() +21
System.Web.Mvc.Async.<>c__DisplayClass8 1.b__7（IAsyncResult ）+12 System.Web.Mvc.Async.WrappedAsyncResult`1.End（）+ 62 System.Web.Mvc。<> c _DisplayClasse.b_ d（ ）+50
System.Web.Mvc.SecurityUtil.b _0（动作f）+7 System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust（动作）+22 System.Web.Mvc.MvcHandler.EndProcessRequest（IAsyncResult asyncResult）+60
System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest（IAsyncResult结果）+9
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute（）+8862381 System.Web.HttpApplication.ExecuteStep（IExecutionStep步骤，布尔值且已完成）+184

HTML帮助代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Web.Mvc.Html;
using Elixir.Models;

namespace Elixir.HtmlHelpers
{
    public static class HtmlHelperExtensions
    {
        public static string ParentMenus(this HtmlHelper html,IEnumerable<Menus> menu)
        {
            string htmloutput=string.Empty;
            if (menu.Count() > 0)
            {
                htmloutput += "<ul class='side-navigation accordion' id='nav-accordion'>";
                var MainMenu = from mainMenu in menu where mainMenu.MainMenuId == null orderby mainMenu.MenuOrder select mainMenu;
                foreach(Menus m in MainMenu)
                {
                    htmloutput += "<li>";
                    htmloutput += "<li><i class='icon-home'>";
                    htmloutput += LinkExtensions.ActionLink(html, m.LinkName, m.ActionName, m.ControllerName);
                    htmloutput += "</li>";
                    htmloutput += "</li></i>";
                }
                htmloutput += "</ul>";
            }
            return htmloutput;

        }

        public static string SubMenu(this HtmlHelper html, IEnumerable<Menus> SubMenu, int MenuId)
        {
            string htmlOutput = string.Empty;
            if (SubMenu.Count() > 0)
            {
                htmlOutput += "<ul class='side-navigation accordion' id='nav-accordion'>";
                var subMenu = from SMenu in SubMenu where SMenu.MainMenuId == MenuId orderby SMenu.MenuOrder select SMenu;
                foreach (Menus m in subMenu)
                {
                    htmlOutput += "<li>";
                    htmlOutput += "<li><i class='icon-home'>";
                    htmlOutput += LinkExtensions.ActionLink(html, m.LinkName, m.ActionName, m.ControllerName);
                    htmlOutput += "</li>";
                    htmlOutput += "</li></i>";
                }
                htmlOutput += "</ul>";
            }
            return htmlOutput;
        }

    }
}

控制器代码

public ActionResult Menus()
        {
            var MMenu = ment.Menu.ToList();
            return PartialView(MMenu);
        }

Menu.cshtml（部分布局）

@model IEnumerable<Elixir.Models.Menus>

<div>
    @Html.Raw(@Html.ParentMenus(Model))



    </div>

索引页

@{
    ViewBag.Title = "Elixir ERP V1.0 Beta";
    Layout = "~/Views/Shared/_LayoutUser.cshtml";
}
<div class="main-container">
    <div class="main-wrapper">
        <div class="scroll-top">
            <a href="#" class="tip-top" title="Go Top"><i class="icon-arrow-up"></i></a>
        </div>
        <div class="left-bar merge-left">
            <!-- SEARCH BAR -->
            <!-- LEFT NAV -->
          @section leftnav{

             <div class="left-nav">
             @Html.Partial("Menus");
             </div>


          }
        </div>
    </div>
    <div class="container">
    </div>
</div>

菜单型号

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace Elixir.Models
{
    [Table("tbl_Menus")]
    public class Menus
    {
        [Key]
        public int MenuId { get; set; }
        public string UserName { get; set; }
        public string MenuName { get; set; }
        public int MenuOrder { get; set; }
        public int? MainMenuId { get; set; }
        public string LinkName { get; set; }
        public string ActionName { get; set; }
        public string ControllerName { get; set; }

    }
}

错误

Answer 1

您的Menu.cshtml应该是Menus.cshtml吗？

如果是这样，您可以在此行中将其作为部分调用：

@Html.Partial("Menus");

但是您没有给它一个模型。

尝试使用

@Html.Action("Menus")