在 .NET4.5 上安装 EntityFramework5.0.0 后错误：“System.Data.Entity.Internal.AppConfig”的类型初始化程序在运行时引发异常

Question

我再次提出这个问题，因为之前的问题尚未解决。

我已经安装了 EntityFramework 5.0.0 on.Net 4.5 (MVC4)，通过使用 linq 查询来获取基于 id 的员工的结果。

public ActionResult Details(int id)
{
    EmployeeContext empctxt = new EmployeeContext();
    Employee employee = empctxt.Employees.Single(emp => emp.employeeid == id);
    return View(employee);
}

应显示输入的员工 ID 的记录，但运行时错误The type initializer for 'System.Data.Entity.Internal.AppConfig' threw an exception. 就行EmployeeContext empctxt = new EmployeeContext();

Web.配置：

<?xml version="1.0" encoding="utf-8"?>
<!--
  For more information on how to configure your ASP.NET application, please visit
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->

<configuration>
  <configSections>

  <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
  <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 --></configSections>
  <appSettings>
    <add key="webpages:Version" value="2.0.0.0" />
    <add key="webpages:Enabled" value="false" />
    <add key="PreserveLoginUrl" value="true" />
    <add key="ClientValidationEnabled" value="true" />
    <add key="UnobtrusiveJavaScriptEnabled" value="true" />
  </appSettings>

  <system.web>

    <httpRuntime targetFramework="4.5" />

    <compilation debug="true" targetFramework="4.5" />

    <pages>
      <namespaces>
        <add namespace="System.Web.Helpers" />
        <add namespace="System.Web.Mvc" />
        <add namespace="System.Web.Mvc.Ajax" />
        <add namespace="System.Web.Mvc.Html" />
        <add namespace="System.Web.Routing" />
        <add namespace="System.Web.WebPages" />
      </namespaces>
    </pages>
  </system.web>

  <system.webServer>
    <validation validateIntegratedModeConfiguration="false" />

  <handlers>
      <remove name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" />
      <remove name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" />
      <remove name="ExtensionlessUrlHandler-Integrated-4.0" />
      <add name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework\v4.0.30319\aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness32" responseBufferLimit="0" />
      <add name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness64" responseBufferLimit="0" />
      <add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
    </handlers></system.webServer>
  <entityFramework>
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>
<connectionStrings>
  <add name="EmployeeContext" providerName="System.Data.SqlClient" connectionString="SERVER=DESKTOP-DO6F13P;DATABASE=mvctrialdbase;uid=sa;pwd=sa@123;"/>
</connectionStrings>
</configuration>

Answer 1

问题出在web.config中。 在添加Entity Framework时， <provider></provider>标签会自动添加到web.config文件中。

自动添加代码：

<entityFramework>
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>

因此<provider></provider>标签需要被删除或必须评论。