同一数据库中的多个数据库上下文和EF 6中的应用程序以及代码优先迁移

我是实体框架的新手。我正在尝试设置使用EF 6的MVC应用程序。我正在使用代码优先迁移。我在应用程序中使用Areas，并且希望每个区域中都有不同的DbContext来分解它。我知道EF 6具有ContextKey，但是我找不到有关如何使用它的完整信息。目前，我一次只能使用一个上下文的迁移。

有人可以提供一个足够详细的示例，让像我这样的EF新手了解和使用。

实体框架6 DbContext通过添加-ContextTypeName和-MigrationsDirectory标志，增加了对Multiple 的支持。我只是在程序包管理器控制台中运行了命令，然后将输出粘贴到下面...

如果您DbContext的项目中有2 s并运行enable-migrations，则会出现错误（您可能已经知道）：

PM> enable-migrations
More than one context type was found in the assembly 'WebApplication3'.
To enable migrations for 'WebApplication3.Models.ApplicationDbContext', use Enable-Migrations -ContextTypeName WebApplication3.Models.ApplicationDbContext.
To enable migrations for 'WebApplication3.Models.AnotherDbContext', use Enable-Migrations -ContextTypeName WebApplication3.Models.AnotherDbContext.

因此，您必须分别运行enable-migrations每个DbContext。而且您必须Configuration.cs为要生成的每个文件指定一个文件夹...

PM> Enable-Migrations -ContextTypeName ApplicationDbContext -MigrationsDirectory Migrations\ApplicationDbContext
Checking if the context targets an existing database...
Code First Migrations enabled for project WebApplication3.

PM> Enable-Migrations -ContextTypeName AnotherDbContext -MigrationsDirectory Migrations\AnotherDbContext
Checking if the context targets an existing database...
Code First Migrations enabled for project WebApplication3.

要为每个添加迁移DbContext，您可以通过指定类的完全限定名称来做到这一点Configuration：

PM> Add-Migration -ConfigurationTypeName WebApplication3.Migrations.ApplicationDbContext.Configuration "InitialDatabaseCreation"
Scaffolding migration 'InitialDatabaseCreation'.
The Designer Code for this migration file includes a snapshot of your current Code First model. This snapshot is used to calculate the changes to your model when you scaffold the next migration. If you make additional changes to your model that you want to include in this migration, then you can re-scaffold it by running 'Add-Migration InitialDatabaseCreation' again.

PM> Add-Migration -ConfigurationTypeName WebApplication3.Migrations.AnotherDbContext.Configuration "InitialDatabaseCreation"
Scaffolding migration 'InitialDatabaseCreation'.
The Designer Code for this migration file includes a snapshot of your current Code First model. This snapshot is used to calculate the changes to your model when you scaffold the next migration. If you make additional changes to your model that you want to include in this migration, then you can re-scaffold it by running 'Add-Migration InitialDatabaseCreation' again.

并且您update-database以相同的方式运行：

PM> Update-Database -ConfigurationTypeName WebApplication3.Migrations.ApplicationDbContext.Configuration
Specify the '-Verbose' flag to view the SQL statements being applied to the target database.
Applying explicit migrations: [201402032113124_InitialDatabaseCreation].
Applying explicit migration: 201402032113124_InitialDatabaseCreation.
Running Seed method.

PM> Update-Database -ConfigurationTypeName WebApplication3.Migrations.AnotherDbContext.Configuration
Specify the '-Verbose' flag to view the SQL statements being applied to the target database.
Applying explicit migrations: [201402032113383_InitialDatabaseCreation].
Applying explicit migration: 201402032113383_InitialDatabaseCreation.
Running Seed method.

希望这可以帮助。