在单独的程序集中启用具有上下文的迁移？

Question

我有一个项目,我想update-database反对我,但我在一个单独的项目中有我的模型和上下文.

如果我运行,enable-migrations我会收到此错误:在程序集"MyProject"中找不到上下文类型.

这可能是因为我的Context在MyProject.MVC中.

如果我enable-migrations针对MyProject.MVC 运行,我必须添加一个app配置文件.我不想这样做,因为我想在许多项目中使用代码.

那么我可以enable-migrations针对MyProject 运行并以某种方式告诉它在MyProject.MVC中查找Context吗？

Answer 1

这仅适用于EF 6,但有一个版本将-ContextProjectName参数添加到-enable-migrations命令中.通过使用此命令,您可以执行以下操作:

enable-migrations -ContextProjectName MyProject.MVC -StartUpProjectName MyProject.MVC 
-ContextTypeName MyProject.MVC.MyContextFolder.MyContextName -ProjectName MyProject

这将MyProject使用中的上下文向项目添加迁移MyProject.MVC.您需要确保具有迁移的项目具有对您的Context的项目的引用,即MyProject引用MyProject.MVC

Answer 2

您只能在包含Database Context类的项目中运行"Enable-Migrations".

您的解决方案将包含2个项目:

1) MyProject.Models
    |- Migrations
        |- 201401061557314_InitialCreate.cs
        |- Configuration.cs
    |- MyContext.cs
    |- App.config (no connection string)

App.config中

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
  </configSections>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework" />
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>
</configuration>

2) MyProject.MVC
        |- Filters
            |- InitializeSimpleMembershipAttribute.cs

InitializeSimpleMembershipAttribute.cs

namespace MyProject.MVC.Filters
{
    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false, Inherited = true)]
    public sealed class InitializeSimpleMembershipAttribute : ActionFilterAttribute
    {
        private static SimpleMembershipInitializer _initializer;
        private static object _initializerLock = new object();
        private static bool _isInitialized;

        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            // Ensure ASP.NET Simple Membership is initialized only once per app start
            LazyInitializer.EnsureInitialized(ref _initializer, ref _isInitialized, ref _initializerLock);
        }

        private class SimpleMembershipInitializer
        {
            public SimpleMembershipInitializer()
            {
                try
                {
                    Database.SetInitializer<MyContext>(new MigrateDatabaseToLatestVersion<MyContext, MyProject.Model.Migrations.Configuration>());

                    using (var context = new MyContext())
                    {
                        context.Database.Initialize(force: true);
                        if (!context.Database.Exists())
                        {
                            // Create the SimpleMembership database without Entity Framework migration schema
                            ((IObjectContextAdapter)context).ObjectContext.CreateDatabase();
                        }
                    }

                    WebSecurity.InitializeDatabaseConnection("DefaultConnection", "UserProfile", "UserId", "UserName", autoCreateTables: true);
                }
                catch (Exception ex)
                {
                    throw new InvalidOperationException("The ASP.NET Simple Membership database could not be initialized. For more information, please see http://go.microsoft.com/fwlink/?LinkId=256588", ex);
                }
            }
        }
    }
}

将MyProject.MVC设置为启动项目

在包管理器中,选择项目:MyProject.Models

然后运行"启用 - 迁移"以在MyProject.Models中创建"迁移"文件夹

接下来是"更新 - 数据库" - >迁移将使用启动项目中的Web.config中的连接字符串来执行迁移