Entity Framework 6 SQL 没有配置文件的 Server Compact 3.5

Question

我正在尝试使用 Entity Framework 6 使用 EntityFramework.SqlServerCompact.Legacy 6.1.3.

访问 SQL Server Compact 3.5 数据库

我的应用程序是一个 Visual Studio 扩展，我无法向应用程序配置文件添加任何内容。

如果我做一个简单的测试应用程序，我可以毫无问题地连接到数据库。如果我尝试从 class 库访问数据库，它会失败并显示错误消息

Schema specified is not valid. Errors: ProjectTemplate.ssdl(2,2) : error 0152: No Entity Framework provider found for the ADO.NET provider with invariant name 'System.Data.SqlServerCe.3.5'. Make sure the provider is registered in the 'entityFramework' section of the application config file. See http://go.microsoft.com/fwlink/?LinkId=260882 for more information.

我找到了一些有趣的链接，例如 here and here，但我无法使其正常工作，因为该示例适用于 EF5 或 SQL 服务器（或者我有问题我的眼睛）。

我该怎么做？

Answer 1

我目前正在使用控制台应用程序和 class 库进行测试。控制台应用程序对 Entity Framework 一无所知，只是调用 class 库中的一个方法。

static void Main(string[] args)
{
  EFTest t = new EFTest();
  t.Test();
}

这是 class 库中的代码。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
using System.Data.Entity.Core.EntityClient;

namespace EF6_SQLCompact_CleanTest_000
{
  public class EFTest
  {
    public void Test()
    {
      try
      {
        // Add an event handler for DbConfiguration.Loaded, which adds our dependency 
        // resolver class to the chain of resolvers.
        System.Data.Entity.DbConfiguration.Loaded += (_, a) => {
          a.AddDependencyResolver(new MyDependencyResolver(), true);
        };

        // Define the provider connection string, specifying the SQL Server Compact 3.5 filename.
        String FileName = @"f:\DotNetTestProjects15\CS\SQLCompact35DllTest\SQLCompact35DllTest\ProjectTemplate.sdf";
        String ConnectionString = String.Format("Data Source={0}", FileName);

        // Create the entity framework connection string, specifying the model,
        // the provider and the provider connection string.
        var builder = new EntityConnectionStringBuilder();
        builder.Metadata = @"res://*/ProjectTemplate.csdl|res://*/ProjectTemplate.ssdl|res://*/ProjectTemplate.msl";
        builder.Provider = "System.Data.SqlServerCe.3.5";
        builder.ProviderConnectionString = ConnectionString;

        // Create the entity framework kontext
        Entities Context = new Entities(builder.ToString());

        // Do a trivial query as a test.
        int i = Context.Languages.Count();
        MessageBox.Show(i.ToString());
      }
      catch (Exception e)
      {
        MessageBox.Show(e.Message);
      }
    }
  }

  // Define an additional constructor for the Entities class, so that we can 
  // pass the connection string into the base class DbContext.
  public partial class Entities : DbContext
  {
    public Entities(String ConnectionString)
      : base(ConnectionString)
    {
    }
  }

  class MyDependencyResolver : System.Data.Entity.Infrastructure.DependencyResolution.IDbDependencyResolver
  {
    public object GetService(Type type, object key)
    {
      // Output the service attempting to be resolved along with it's key 
      System.Diagnostics.Debug.WriteLine(string.Format("MyDependencyResolver.GetService({0}, {1})", type.Name, key == null ? "" : key.ToString()));

      if ((type == typeof(System.Data.Common.DbProviderFactory))
           && (key != null)
           && ((string)(key) == "System.Data.SqlServerCe.3.5"))
      {
        return System.Data.SqlServerCe.SqlCeProviderFactory.Instance ;
      }
      else if ((type == typeof(System.Data.Entity.Core.Common.DbProviderServices))
                && (key != null)
                && ((string)(key) == "System.Data.SqlServerCe.3.5"))
      {
        return System.Data.Entity.SqlServerCompact.Legacy.SqlCeProviderServices.Instance ;
      }
      else if ((type == typeof(System.Data.Entity.Infrastructure.IProviderInvariantName))
                && (key is System.Data.SqlServerCe.SqlCeProviderFactory))
      {
        return new MyProviderInvariantName();
      }

      return null;
    }

    public IEnumerable<object> GetServices(Type type, object key)
    {
      return new object[] { GetService(type, key) }.ToList().Where(o => o != null);
    }
  }

  // Implement IProviderInvariantName so that we can return an object when
  // requested in GetService()
  class MyProviderInvariantName : IProviderInvariantName
  {
    public string Name
    {
      get { return "System.Data.SqlServerCe.3.5"; }
    }
  }
}

依赖项解析器基于 EricEJ 提到的 link 中 Ryan Griffith 的回答。

这似乎在我的测试程序的上下文中有效，但我还没有在 Visual Studio 扩展的上下文中尝试过。

据我所知，只有在 AppDomain 中首次加载 DbConfiguration 之前将事件处理程序添加到 DbConfiguration.Loaded 时，此技术才会起作用（我可能无法保证).我还担心它可能对 Visual Studio 或其他 Visual Studio 扩展有副作用。

Entity Framework 6 SQL 没有配置文件的 Server Compact 3.5

Entity Framework 6 SQL Server Compact 3.5 without Config file

c#

.net

entity-framework

sql-server-ce

app-config