找不到具有不变名称"System.Data.SqlServerCe.4.0"的ADO.NET提供程序的实体框架提供程序

Question

当我使用sqlce 4.0 with entityframework 6.0时出现以下错误

No Entity Framework provider found for the ADO.NET provider with invariant name 'System.Data.SqlServerCe.4.0'

我的app.config看起来像这样

....
<configSections>
    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" requirePermission="false" />
    <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 -->
  <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 --></configSections>
 <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework" >
      <parameters>
        <parameter value =" System.Data.SqlServerCe.4.0" />
      </parameters>
    </defaultConnectionFactory>
    <!--providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers-->
  </entityFramework>
  <connectionStrings>
    <add name="FbMultipleInsOrderContainer" connectionString="metadata=res://*/FbMultipleInsOrder.csdl|res://*/FbMultipleInsOrder.ssdl|res://*/FbMultipleInsOrder.msl;provider=System.Data.SqlServerCe.4.0;provider connection string=&quot;data source=|DataDirectory|\FBMultipleOrderSync.sdf&quot;" providerName="System.Data.EntityClient" />
  </connectionStrings>
...

我尝试重新安装EF 6.但没有用.

任何关于此的线索都会非常明显.

Answer 1

安装EntityFramework.SqlServerCompact nuget包后,检查您的app.config是否包含以下内容(根据@ ErikEJ上面的注释):

<providers>
  <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
  <provider invariantName="System.Data.SqlServerCe.4.0" type="System.Data.Entity.SqlServerCompact.SqlCeProviderServices, EntityFramework.SqlServerCompact" />
</providers>

(即使你真的不需要它,你也可以为SqlClient保留这一行.)

Answer 2

ErikEJ指出了这一点,但我想强调一下,你必须记得安装Nuget包

EntityFramework.SqlServerCompact

我尝试按照建议的答案,但没有意识到我没有App.config引用所需的NuGet包.

Answer 3

我在单元测试中遇到了这个问题.棘手的是错误不是经常出现的.我设法通过添加以下类我的单元测试解决方案来解决它:

public static class Trick
{
    public static void FixEfProviderServicesProblem()
    {
        // this commented line should be used for SQL Server provider
        //var instance = System.Data.Entity.SqlServer.SqlProviderServices.Instance;

        // this is used for SQL Server CE provider
        var instance = System.Data.Entity.SqlServerCompact.SqlCeProviderServices.Instance;
    }
}

Answer 4

要实现这一点,您只需EntityFramework.SqlServerCompact在Package Manager控制台中注册,

要执行此操作,请打开电源管理器控制台并键入以下命

PM> Install-Package EntityFramework.SqlServerCompact