同一配置文件中有两个不同的提供程序

Question

我正在使用EntityFramework 6.1.0

我有2个提供者.MysqlClient和SQLServerCE,我需要创建2个不同的DBContext.这迫使我创建了2个配置类,因为mysql有一些不同的东西.但是当我初始化应用程序时,Database.DefaultConnectionFactory它来自defaultConnectionFactory(配置文件),并且我无法指定在daterminated Context上采用什么提供程序.

怎么做？

我的配置文件:

<entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlCeConnectionFactory, EntityFramework">
        <parameters>
          <parameter value="System.Data.SqlServerCe.4.0" />
        </parameters>
    </defaultConnectionFactory>
    <providers>
        <provider invariantName="MySql.Data.MySqlClient" type="MySql.Data.MySqlClient.MySqlProviderServices, MySql.Data.Entity.EF6" />
        <provider invariantName="System.Data.SqlServerCe.4.0" type="System.Data.Entity.SqlServerCompact.SqlCeProviderServices, EntityFramework.SqlServerCompact" />
     </providers>
</entityFramework>

Mysql上下文:

namespace Sistema.DataAccess
{
    [DbConfigurationType(typeof(Sistema.DataAccess.Migrations.Configuration))] 
    public class SistemaContext : Sistema.Common.Repository.DataContext
    {
        static SistemaContext()
        {
            Database.SetInitializer(new MigrateDatabaseToLatestVersion<SistemaContext, Sistema.DataAccess.Migrations.Configuration>());
        }
        public SistemaContext()
            : base(GetConnectionString())
        {

        }
        private static string GetConnectionString()
        { 
                return "Server=127.0.0.1;Database=?????;Uid=????;Pwd=????;Port=3306;";//MySQL
        }
    }
}

SQLCe背景:

namespace Sistema.DataAccess
{
    [DbConfigurationType(typeof(Sistema.DataAccess.Migrations.Configuration2))]
    public class SistemaContext2 : Sistema.Common.Repository.DataContext
    {
        static SistemaContext2()
        {
            Database.SetInitializer(new MigrateDatabaseToLatestVersion<SistemaContext2, Sistema.DataAccess.Migrations.Configuration2>());
        }
        public SistemaContext2()
            : base(GetConnectionString())
        {

        }
        private static string GetConnectionString()
        {
            return "Data Source=C:/teste2.sdf;Persist Security Info=False;";//SQLCE
        }
    }
}

Mysql配置

 public sealed class Configuration : DbMigrationsConfiguration<Sistema.DataAccess.SistemaContext>
    {
        public Configuration()
        {
            DbInterception.Add(new NLogCommandInterceptor());// guardar logs

            AutomaticMigrationsEnabled = true;
            AutomaticMigrationDataLossAllowed = true;

            SetSqlGenerator("MySql.Data.MySqlClient", new MySql.Data.Entity.MySqlMigrationSqlGenerator());//Mysql da erro se nao colocar isso.(Pelo que vi da para colocar no App.config tambem.)
            SetHistoryContextFactory("MySql.Data.MySqlClient", (conn, schema) => new MySQLHistoryContext(conn, schema));
        }
    }

SQLCE配置

public sealed class Configuration2 : DbMigrationsConfiguration<Sistema.DataAccess.SistemaContext2>
    {
        public Configuration2()
        {
            DbInterception.Add(new NLogCommandInterceptor());// guardar logs

            AutomaticMigrationsEnabled = true;
            AutomaticMigrationDataLossAllowed = true;
        }
    }

Answer 1

首先,您使用了错误的配置类.DbConfigurationType需要从DbConfiguration继承而不是DbMigrationsConfiguration <>的类型.

DbMigrationsConfiguration实际上只用于Migrators和DatabaseInitializers.

public class MyDbConfiguration : DbConfiguration
{
    public MyDbConfiguration()
    {
        this.SetDefaultConnectionFactory(new System.Data.Entity.Infrastructure.SqlCeConnectionFactory("System.Data.SqlServerCe.4.0"));

        this.SetProviderServices("System.Data.SqlServerCe.4.0", SqlCeProviderServices.Instance);

        this.AddInterceptor(new NLogCommandInterceptor());// guardar logs

        this.SetMigrationSqlGenerator("System.Data.SqlServerCe.4.0", () => new SqlCeMigrationSqlGenerator());
    }
}

[DbConfigurationType(typeof(MyDbConfiguration))]
public class TestContext : DbContext

遗憾的是,即使使用多个DbConfiguration,也无法设置多个DefaultConnectionFactories.

在您的情况下,您必须将连接字符串存储在app.config中,并将名称传递给DbContext构造函数.

public class TestContext : DbContext
    {
        public TestContext()
            : base("name=MyConnectionString")
        {

        }

将根据app.config中MyConnectionString的提供程序名称初始化连接

或者,如果您不希望app.config中的连接字符串将刚已初始化的DbConnection传递给DbContext构造函数

public class TestContext : DbContext
    {
        public TestContext()
            : base(new SqlCeConnection(GetConnectionString()),true)
        {

        }

或者,如果您不想初始化特定连接,请使用DbProviderFactory.

public class TestContext : DbContext
    {
        public TestContext()
            : base(GetConnection(),true)
        {

        }

        public static DbConnection GetConnection() { 
            var factory = DbProviderFactories.GetFactory("System.Data.SqlServerCe.4.0");
            var connection = factory.CreateConnection();
            connection.ConnectionString = "Data Source=C:/teste2.sdf;Persist Security Info=False;";
            return connection;
        }

Answer 2

解决!(对我而言)

我的配置文件

  <entityFramework>
    <providers>
      <provider invariantName="MySql.Data.MySqlClient" type="MySql.Data.MySqlClient.MySqlProviderServices, MySql.Data.Entity.EF6" />
      <provider invariantName="System.Data.SqlServerCe.4.0" type="System.Data.Entity.SqlServerCompact.SqlCeProviderServices, EntityFramework.SqlServerCompact" />
    </providers>
  </entityFramework>
  <system.data>
    <DbProviderFactories>
      <remove invariant="MySql.Data.MySqlClient"></remove>
      <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.8.3.0" />
      <remove invariant="System.Data.SqlServerCe.4.0" />
      <add name="Microsoft SQL Server Compact Data Provider 4.0" invariant="System.Data.SqlServerCe.4.0" description=".NET Framework Data Provider for Microsoft SQL Server Compact" type="System.Data.SqlServerCe.SqlCeProviderFactory, System.Data.SqlServerCe, Version=4.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91" />
    </DbProviderFactories>
  </system.data>
</configuration>

2个上下文与问题相同.但我删除[DbConfigurationType(typeof(Sistema.DataAccess.Migrations.Configuration))] 了2个上下文

配置类1(mysql)

public sealed class Configuration : DbMigrationsConfiguration<Sistema.DataAccess.SistemaContext>
    {
        public Configuration()
        {
            DbConfiguration.SetConfiguration(new DbConfigurationBase("MYSQL"));

            DbInterception.Add(new NLogCommandInterceptor());// guardar logs

            AutomaticMigrationsEnabled = true;
            AutomaticMigrationDataLossAllowed = true; 

            SetSqlGenerator("MySql.Data.MySqlClient", new MySql.Data.Entity.MySqlMigrationSqlGenerator());//Mysql da erro se nao colocar isso.(Pelo que vi da para colocar no App.config tambem.)
            SetHistoryContextFactory("MySql.Data.MySqlClient", (conn, schema) => new MySQLHistoryContext(conn, schema));
        }
}

配置2级(SQLCE)

public sealed class Configuration2 : DbMigrationsConfiguration<Sistema.DataAccess.SistemaContext2>
    {
        public Configuration2()
        {
            DbConfiguration.SetConfiguration(new DbConfigurationBase("SQLCE"));

            DbInterception.Add(new NLogCommandInterceptor());// guardar logs

            AutomaticMigrationsEnabled = true;
            AutomaticMigrationDataLossAllowed = true;
        }
}

我使用您的DBConnection Idea来创建连接.