c# - ViewBag 和 HtmlHelper 错误 : "One or more types required to compile a dynamic expression cannot be found. Are you missing an assembly reference?"

Question

ViewBag 错误:“找不到编译动态表达式所需的一种或多种类型。是否缺少程序集引用？”

所有 HTML Helper 方法都包含错误:“无法从用法中推断方法的类型参数。尝试明确指定类型参数。”

在过去两天仔细研究与此错误相关的其他帖子后，这是我尝试过的方法:

• 修复 Visual Studio
• 重新安装 Visual Studio
• 确保我引用了 Microsoft.CSharp 和 System.Core
• 添加到 global.asax:ViewEngines.Engines.Clear()； ViewEngines.Engines.Add(new CustomRazorViewEngine());
• 将Microsoft.CSharp Copy Local的引用值从false改为True
• 今天我安装了 RC 3 更新
• 检查 GAC 的版本(仅包含版本 4.0.0.0)
• 卸载/重新安装最新版本的 .NET 框架

这是我的 Web.Config View :

<?xml version="1.0"?>

<configuration>
  <configSections>
    <sectionGroup name="system.web.webPages.razor" type="System.Web.WebPages.Razor.Configuration.RazorWebSectionGroup, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
      <section name="host" type="System.Web.WebPages.Razor.Configuration.HostSection, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
      <section name="pages" type="System.Web.WebPages.Razor.Configuration.RazorPagesSection, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
    </sectionGroup>
  </configSections>

  <system.web.webPages.razor>
    <host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=5.2.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
    <pages pageBaseType="System.Web.Mvc.WebViewPage">
      <namespaces>
        <add namespace="System.Web.Mvc" />
        <add namespace="System.Web.Mvc.Ajax" />
        <add namespace="System.Web.Mvc.Html" />
        <add namespace="System.Web.Optimization"/>
        <add namespace="System.Web.Routing" />
        <add namespace="WebApplication14" />
      </namespaces>
    </pages>
  </system.web.webPages.razor>

  <appSettings>
    <add key="webpages:Enabled" value="false" />
  </appSettings>

  <system.webServer>
    <handlers>
      <remove name="BlockViewHandler"/>
      <add name="BlockViewHandler" path="*" verb="*" preCondition="integratedMode" type="System.Web.HttpNotFoundHandler" />
    </handlers>
  </system.webServer>
</configuration>

Web.Config:

<?xml version="1.0"?>
<!--
  For more information on how to configure your ASP.NET application, please visit
  http://go.microsoft.com/fwlink/?LinkId=301880
  -->
<configuration>
  <configSections>
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false"/>
  </configSections>
  <connectionStrings>
    <add name="DefaultConnection" connectionString="Data Source=(LocalDb)\v11.0;AttachDbFilename=|DataDirectory|\aspnet-WebApplication14-20140703071149.mdf;Initial Catalog=aspnet-WebApplication14-20140703071149;Integrated Security=True" providerName="System.Data.SqlClient"/>
  </connectionStrings>
  <appSettings>
    <add key="webpages:Version" value="3.0.0.0"/>
    <add key="webpages:Enabled" value="false"/>
    <add key="ClientValidationEnabled" value="true"/>
    <add key="UnobtrusiveJavaScriptEnabled" value="true"/>
  </appSettings>
  <system.web>
    <authentication mode="None"/>
    <compilation debug="true" targetFramework="4.0"/>
    <httpRuntime/>
  </system.web>
  <system.webServer>
    <modules>
      <remove name="FormsAuthentication"/>
    </modules>
  </system.webServer>
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="Newtonsoft.Json" culture="neutral" publicKeyToken="30ad4fe6b2a6aeed"/>
        <bindingRedirect oldVersion="0.0.0.0-6.0.0.0" newVersion="6.0.0.0"/>
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Helpers" publicKeyToken="31bf3856ad364e35"/>
        <bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0"/>
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35"/>
        <bindingRedirect oldVersion="1.0.0.0-5.2.0.0" newVersion="5.2.0.0"/>
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Optimization" publicKeyToken="31bf3856ad364e35"/>
        <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="1.1.0.0"/>
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="System.Web.WebPages" publicKeyToken="31bf3856ad364e35"/>
        <bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0"/>
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="WebGrease" publicKeyToken="31bf3856ad364e35"/>
        <bindingRedirect oldVersion="1.0.0.0-1.5.2.14234" newVersion="1.5.2.14234"/>
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="v11.0"/>
      </parameters>
    </defaultConnectionFactory>
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer"/>
    </providers>
  </entityFramework>
</configuration>

这是我的 Global.asax:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Web.Optimization;
using System.Web.Routing;

namespace WebApplication14
{
    public class MvcApplication : System.Web.HttpApplication
    {
        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);
        }
    }
}

此时真的不知所措。打开全新的 MVC 项目和旧项目时都会发生这种情况。我认为在新安装和更新后错误会消失，但我错了。任何帮助将不胜感激。

示例代码:

   @model WebApplication14.Models.ResetPasswordViewModel
    @{
        ViewBag.Title = "Reset password";
    }

    <h2>@ViewBag.Title.</h2>

    @using (Html.BeginForm("ResetPassword", "Account", FormMethod.Post, new { @class = "form-horizontal", role = "form" }))
    {
        @Html.AntiForgeryToken()
        <h4>Reset your password.</h4>
        <hr />
        @Html.ValidationSummary("", new { @class = "text-danger" })
        @Html.HiddenFor(model => model.Code)
        <div class="form-group">
            @Html.LabelFor(m => m.Email, new { @class = "col-md-2 control-label" })
            <div class="col-md-10">
                @Html.TextBoxFor(m => m.Email, new { @class = "form-control" })
            </div>
        </div>
        <div class="form-group">
            @Html.LabelFor(m => m.Password, new { @class = "col-md-2 control-label" })
            <div class="col-md-10">
                @Html.PasswordFor(m => m.Password, new { @class = "form-control" })
            </div>
        </div>
        <div class="form-group">
            @Html.LabelFor(m => m.ConfirmPassword, new { @class = "col-md-2 control-label" })
            <div class="col-md-10">
                @Html.PasswordFor(m => m.ConfirmPassword, new { @class = "form-control" })
            </div>
        </div>
        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" class="btn btn-default" value="Reset" />
            </div>
        </div>
    }

    @section Scripts {
        @Scripts.Render("~/bundles/jqueryval")
    }

Answer 1

我也遇到过这个问题。在我执行了以下步骤后，这个问题得到了解决:

• 已安装 Visual Studio 更新 3
• 删除所有临时文件(来自\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files、\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files、\AppData\Local\Temp\Temporary ASP.NET Files\root)
• 从项目文件夹和 csproj.user 中删除 {ProjectName}.v12.suo
• 创建一个新的 asp.net mvc 应用程序并将 View web.config 复制到旧应用程序中。这里有旧的(左)和新的(右)之间的区别:http://screencast.com/t/x4WisCWf

编辑:忽略比较文件中的第 20 行。