在 EF6 中的 MySQL/SQL 服务器之间切换

Question

我有一个在 MySQL 和 SQL 服务器上运行的项目。在过去的几周里，我使用基于现有 SQL 服务器架构。

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 MySql.Data.MySqlClient.MySqlConnection 到 System.Data.SqlClient.SqlConnection

的 ClassCastException 上崩溃

代码：

//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();
}

Spring定义：

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

Spring工厂：

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

错误消息（翻译自本地化）

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:\Documents\Visual Studio 2013\Projects\Auitool\Auitool2014\Data\Managers\Spring\NewsManagerImpl.cs:16

配置如下：

  <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" />

编译后如何在两个数据库之间切换？我提到 Spring 是因为我的 DbContext 是 request 范围的对象，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涉及以下 class：System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy。这显然是 SQL 服务器包的一部分。我需要了解 EF 如何实例化它。在 EF 源代码中我 see

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

真的，那一定是 MySql.Data.entity.EF6.MySqlExecutionStrategy

的实例

Answer 1

修复了 EntityFramework 的 configuration

  <entityFramework codeConfigurationType="MySql.Data.Entity.MySqlEFConfiguration, MySql.Data.Entity.EF6">
    <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" />
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>

MySql.Data.Entity.MySqlEFConfiguration 是关键。总结一下，为了从 SQL 服务器切换到 MySQL 我必须：

编辑该死的连接字符串
- 提供商属性始终为 System.Data.EntityClient
- 在连接 string 中，将提供商更改为 MySql.Data.MySqlClient
用上面的

entityFramework

在 EF6 中的 MySQL/SQL 服务器之间切换

Switching between MySQL/SQL Server in EF6

mysql

sql-server

entity-framework-6

调查进展