MySql连接器6.8.2 RC,实体框架6和代码优先

Question

我最近升级到Entity Framework 6并安装了MySql 6.8.2 RC Connector,因为它声称现在支持EF6 Code First.

请记住,在升级之前,我的项目在连接器6.7.4和EF 5中运行良好.

我对web.config进行了以下更改

<defaultConnectionFactory type="MySql.Data.Entity.MySqlConnectionFactory, MySql.Data.Entity.EF6" />
<providers>
  <provider invariantName="MySql.Data.MySqlClient" type="MySql.Data.MySqlClient.MySqlProviderServices, MySql.Data.Entity.EF6, Version=6.8.2.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d"></provider>
  <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
</providers>

<connectionStrings>
<add providerName="MySql.Data.MySqlClient" name="dbcontext" connectionString="Server=localhost; Database=db; Uid=un; Pwd=pw;Convert Zero Datetime=True" />
</connectionStrings>

我还添加了以下引用(.net 4.5版本)

1. MySql.Data
2. MySql.Data.Entity.EF6
3. MySql.Web

问题是 - 代码调用我收到的DBContext的那一刻:

Object reference not set to an instance of an object.

再次 - 请记住,升级之前一切正常,所以我知道它不是代码问题,但是,我可能没有正确设置web.config？

另外 - 您可能会问,如果在升级之前它运行良好,为什么要升级？好吧,据说EF6和新的MySql连接器解决了我遇到的一些错误 - 所以我希望现在实现它,而它在开发中,当它转移到生产(几个月后)我应该能够加载6.8.x连接器的生产版本.

这是堆栈跟踪,以防它有所帮助

[NullReferenceException: Object reference not set to an instance of an object.]
MySql.Data.MySqlClient.MySqlProviderServices.GetDbProviderManifestToken(DbConnection connection) +85
System.Data.Entity.Core.Common.DbProviderServices.GetProviderManifestToken(DbConnection connection) +332
System.Data.Entity.Utilities.DbProviderServicesExtensions.GetProviderManifestTokenChecked(DbProviderServices providerServices, DbConnection connection) +67
System.Data.Entity.Infrastructure.<>c__DisplayClass1.<ResolveManifestToken>b__0(Tuple`3 k) +63
System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory) +72
System.Data.Entity.Infrastructure.DefaultManifestTokenResolver.ResolveManifestToken(DbConnection connection) +260
System.Data.Entity.Utilities.DbConnectionExtensions.GetProviderInfo(DbConnection connection, DbProviderManifest& providerManifest) +89
System.Data.Entity.DbModelBuilder.Build(DbConnection providerConnection) +79
System.Data.Entity.Internal.LazyInternalContext.CreateModel(LazyInternalContext internalContext) +143
System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input) +171
System.Data.Entity.Internal.LazyInternalContext.InitializeContext() +594
System.Data.Entity.Internal.InternalContext.Initialize() +31
System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType) +39
System.Data.Entity.Internal.Linq.InternalSet`1.Initialize() +138
System.Data.Entity.Internal.Linq.InternalSet`1.Include(String path) +41
System.Data.Entity.Infrastructure.DbQuery`1.Include(String path) +142
[edited].Global.Application_BeginRequest(Object sender, EventArgs e) in c:\edited\Global.asax.cs:47
System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +136
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +69

Answer 1

当所有内容都在一个MVC项目中时,我有MySQL EF6和Migrations.我把它拆分成层(核心[接口/权限],数据,服务和Web)并开始得到Loren提到的相同错误.

弄清楚它没有从MVC应用程序中获取连接字符串.事实证明,我所要做的就是在我的Data项目中的App.config中重新创建连接字符串(DbContext和映射所在的位置).

这些是我为使一切工作而采取的步骤:

步骤1)使用NuGet导入MySql.Data.Entities(截至本文的当前版本为6.8.3.0)

步骤2)将以下内容添加到App.config和/或Web.config:

<connectionStrings>
    <add name="MyDB" providerName="MySql.Data.MySqlClient" connectionString="Data Source=localhost; port=3306; Initial Catalog=mydb; uid=myuser; pwd=mypass;" />
  </connectionStrings>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework" />
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
      <provider invariantName="MySql.Data.MySqlClient" type="MySql.Data.MySqlClient.MySqlProviderServices, MySql.Data.Entity.EF6, Version=6.8.3.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d"></provider>
    </providers>
  </entityFramework>

步骤3)设置您的DbContext以使用MySql:

using MyApp.Core.Entities.Directory;
using MyApp.Data.Mapping;
using System.Data.Entity;

namespace MyApp.Data
{
    [DbConfigurationType(typeof(MySql.Data.Entity.MySqlEFConfiguration))]
    public class MyContext : DbContext
    {
        public MyContext() : this("MyDB") { }
        public MyContext(string connStringName) : base(connStringName) {}
        static MyContext ()
        {
            // static constructors are guaranteed to only fire once per application.
            // I do this here instead of App_Start so I can avoid including EF
            // in my MVC project (I use UnitOfWork/Repository pattern instead)
            DbConfiguration.SetConfiguration(new MySql.Data.Entity.MySqlEFConfiguration());
        }

        public DbSet<Country> Countries { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            // I have an abstract base EntityMap class that maps Ids for my entities.
            // It is used as the base for all my class mappings
            modelBuilder.Configurations.AddFromAssembly(typeof(EntityMap<>).Assembly);
            base.OnModelCreating(modelBuilder);
        }
    }
}

步骤4)在Package Manager控制台中将Default Project设置为Data项目

步骤5)使用enable-migrations,add-migration,update-database就像你通常会

Answer 2

ContosoUniversity MVC5 + EF6代码第一种方法使用MySQL示例下载:http://www.nzmk.com/Blogs/BlogsView/tabid/83/EntryId/8/MVC5-EF6-ContosoUniversity-code-first-approach-using-MySQL . ASPX

要开始使用Entity Framework 6和Visual Studio 2013,必须为Visual Studio 1.1.1 MySQL Connector/Net 6.8.3 GA安装MySQL

可以使用以下链接下载用于Visual Studio 1.1.1 Beta的MySQL:cdn.mysql.com/Downloads/MySQLInstaller/mysql-visualstudio-plugin-1.1.1.msi

MySQL Connector/Net 6.8.3 GA dev.mysql.com/downloads/connector/net/

开始使用VS 2013和EF 6

1. 为Visual Studio和Connector/Net卸载旧版本的MySQL
2. 为Visual Studio 1.1.1安装MySQL
3. 安装Connector/Net 6.8.3
4. 将MySql.Data,MySql.Data.Entity.EF6,MySql.Web(Version 6.8.3.0)程序集的引用添加到项目中.根据所使用的.NET Framework,将从v4.0或v4.5文件夹中获取程序集.

5. 编辑web.config或app.config

   <connectionStrings>
       <add name='SchoolContext' connectionString='Data Source=xxxxx;port=3306;Initial Catalog=ContosoUniversity;user id=root;password=xxxxxxxxx;' providerName='MySql.Data.MySqlClient'/>
    </connectionStrings>
    <entityFramework codeConfigurationType='MySql.Data.Entity.MySqlEFConfiguration, MySql.Data.Entity.EF6'>
       <defaultConnectionFactory type='System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework'/>
       <providers>
         <provider invariantName='MySql.Data.MySqlClient' type='MySql.Data.MySqlClient.MySqlProviderServices,
   

   MySql.Data.Entity.EF6'/>
   

6. 编辑SchoolContext.cs

   ....使用MySql.Data.Entity;

   namespace ContosoUniversity.DAL
   {
     [DbConfigurationType(typeof(MySqlEFConfiguration))]
     public class SchoolContext : DbContext
     {
     ....
     }
   }
   

7. 编辑Global.asax.cs

   ......使用MySql.Data.Entity;

   namespace ContosoUniversity
   {
       public class MvcApplication : System.Web.HttpApplication
       {
           protected void Application_Start()
           {
               AreaRegistration.RegisterAllAreas();
               FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
               RouteConfig.RegisterRoutes(RouteTable.Routes);
               BundleConfig.RegisterBundles(BundleTable.Bundles);
   
               DbConfiguration.SetConfiguration(new MySqlEFConfiguration());
           }
       }
   }