在EF6中切换MySQL / SQL Server

Question

我有一个在mysql和SQL Server上运行的项目。在过去的几周里，我已经设法使用基于现有SQL Server架构的数据库优先设计将其从普通旧SQL“迁移”到实体框架（也使用Spring依赖注入）。

现在我需要用MySQL进行测试。即使我使用了“适当的”MySQL配置，应用程序也会在从ClassCastException到MySql.Data.MySqlClient.MySqlConnection的System.Data.SqlClient.SqlConnection上崩溃

码：

//Autowired by Spring
public auitool2014Entities DataContext{get;set;}

public IList<News> FindAllValid()
{
    return (from News news in DataContext.news where news.annullata == 0 select news).ToList();
}

春季定义：

<object id="dataContext" singleton="false" scope="request" type="DiagnosticoSite.Models.auitool2014Entities, Auitool2014" factory-object="dataContextFactory" factory-method="Build" destroy-method="Dispose" ></object>

春天工厂：

public auitool2014Entities Build()
{
    return new auitool2014Entities();
}

错误消息（从本地化翻译）

Unable to cast object of type 'MySql.Data.MySqlClient.MySqlConnection' to type 'System.Data.SqlClient.SqlConnection'.

跟踪堆栈跟踪：

[InvalidCastException: Unable to cast object of type 'MySql.Data.MySqlClient.MySqlConnection' type 'System.Data.SqlClient.SqlConnection'.]
   System.Data.SqlClient.SqlCommand.set_DbConnection(DbConnection value) +26
   System.Data.Common.DbCommand.set_Connection(DbConnection value) +9
   System.Data.Entity.Internal.InterceptableDbCommand.set_DbConnection(DbConnection value) +41
   System.Data.Common.DbCommand.set_Connection(DbConnection value) +9
   System.Data.Entity.Core.Common.Utils.CommandHelper.SetStoreProviderCommandState(EntityCommand entityCommand, EntityTransaction entityTransaction, DbCommand storeProviderCommand) +123
   System.Data.Entity.Core.EntityClient.Internal.EntityCommandDefinition.PrepareEntityCommandBeforeExecution(EntityCommand entityCommand) +314
   System.Data.Entity.Core.EntityClient.Internal.EntityCommandDefinition.ExecuteStoreCommands(EntityCommand entityCommand, CommandBehavior behavior) +70
   System.Data.Entity.Core.Objects.Internal.ObjectQueryExecutionPlan.Execute(ObjectContext context, ObjectParameterCollection parameterValues) +1283
   System.Data.Entity.Core.Objects.<>c__DisplayClass7.<GetResults>b__6() +185
   System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction(Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess) +448
   System.Data.Entity.Core.Objects.<>c__DisplayClass7.<GetResults>b__5() +271
   System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Func`1 operation) +251
   System.Data.Entity.Core.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption) +648
   System.Data.Entity.Core.Objects.ObjectQuery`1.<System.Collections.Generic.IEnumerable<T>.GetEnumerator>b__0() +68
   System.Data.Entity.Internal.LazyEnumerator`1.MoveNext() +68
   System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) +381
   System.Linq.Enumerable.ToList(IEnumerable`1 source) +58
   DiagnosticoSite.Data.Managers.Spring.NewsManagerImpl.FindAllValid() in d:DocumentsVisual Studio 2013ProjectsAuitoolAuitool2014DataManagersSpringNewsManagerImpl.cs:16

配置完成后：

  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="v11.0" />
      </parameters>
    </defaultConnectionFactory>
    <providers>
      <provider invariantName="MySql.Data.MySqlClient" type="MySql.Data.MySqlClient.MySqlProviderServices, MySql.Data.Entity.EF6, Version=6.9.5.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" />
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>
  <system.data>
    <DbProviderFactories>
      <remove invariant="MySql.Data.MySqlClient" />
      <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.9.5.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" />
    </DbProviderFactories>
  </system.data>

我基本上将连接字符串更改为MySQL连接字符串

<add name="myConnectionString" connectionString="metadata=res://*/Models.Auitool2014.csdl|res://*/Models.Auitool2014.ssdl|res://*/Models.Auitool2014.msl;provider=Mysql.Data.MysqlClient;provider connection string=&quot;Server=localhost;Database=auitemp;Uid=root;Pwd=root;Allow Zero Datetime=True;CharSet=latin1;Pooling=True;Min Pool Size=5&quot;" providerName="System.Data.EntityClient" />

如何在两个DB之间进行编译后进行切换？我提到Spring是因为我的DbContext是request-scoped对象，可以通过工厂对象轻松实例化。

调查进展

我发现堆栈跟踪报告了以下涉及的类：System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy。这显然是SQL Server包的一部分。我需要了解EF如何实例化它。在EF源代码我see

var executionStrategy = ExecutionStrategy
                                    ?? DbProviderServices.GetExecutionStrategy(QueryState.ObjectContext.Connection, QueryState.ObjectContext.MetadataWorkspace);

真的，那必须是MySql.Data.entity.EF6.MySqlExecutionStrategy的一个实例