具有多个 DBContext 的 EF 7 迁移 [英] EF 7 Migrations with multiple DBContexts

问题描述

我在搭建和从具有多个 DBContext 的类库进行迁移时遇到问题.我找到了一个类似于迁移的命令行参数:

I have a problem scaffolding and doing migrations from a class library with multiple DBContexts. I found a command line argument that looks like this for migrations:

dnx ef migration add -c Contexts.IndustryContext initial

但这甚至无法通过命令行解析器获得.我希望我所有的 DBContexts 和数据库内容都来自主 MVC 6 web 项目和它们自己的 DLL.这可能吗?需要什么命令行魔法?

But this doesn't even get by the command line parser. I want all my DBContexts and database stuff out of the main MVC 6 web project and in their own DLLs. Is this possible? What command line magic is required?

推荐答案

我正在寻找这个问题的答案，并希望为 ef core 2.0 提供我的解决方案.

I was looking for an answer to this question and wanted to provide my solution for ef core 2.0.

Microsoft.EntityFrameworkCore.Tools.DotNet 需要添加到每个包含 DbContext 的类库中.右键单击项目并选择Edit *.csproj.然后，添加以下内容:

Microsoft.EntityFrameworkCore.Tools.DotNet needs to be added to each of your class libraries that have a DbContext in them. Right click the project and select Edit *.csproj. Then, add the following:

  <ItemGroup>
    <DotNetCliToolReference Include="Microsoft.EntityFrameworkCore.Tools.DotNet" Version="2.0.0-preview2-final" />
  </ItemGroup>

注意:该版本是本文发布时的最新版本，未来可能会发生变化.

Note: the version is the latest at the time of this post and will likely change in the future.

接下来，我创建了一个名为 Migrations.Console 的新控制台应用程序 (.NET Core) 并将其添加到我的解决方案中.您必须引用此项目中的所有 DbContext 类库.

Next, I created a new Console App (.NET Core) called Migrations.Console and added it to my Solution. You will have to reference all of your DbContext class libraries in this project.

我安装了 Microsoft.EntityFrameworkCore 和 Microsoft.EntityFrameworkCore.Design Nuget 包.

I installed Microsoft.EntityFrameworkCore and Microsoft.EntityFrameworkCore.Design Nuget packages.

在 Migrations.Console 应用程序中，我为我拥有的每个 Db 上下文创建了一个 DbContextFactory 类.

In the Migrations.Console app, I created a DbContextFactory class for each Db context I have.

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Design;

public class ApplicationDbContextFactory : IDesignTimeDbContextFactory<ApplicationDbContext>
{
    public ApplicationDbContext CreateDbContext(string[] args)
    {
        var builder = new DbContextOptionsBuilder<ApplicationDbContext>();
        builder.UseSqlServer("Server=(local);Database=DATABASENAME;Trusted_Connection=True;MultipleActiveResultSets=true");
        return new ApplicationDbContext(builder.Options);
    }
}

注意:确保更新上下文和连接字符串以匹配您的项目.

Note: Make sure you update the context and connection string to match your project.

现在创建了每个 DbContextFactory，您可以开始创建迁移.转到您的类库的文件夹.最简单的方法是右键单击项目并在文件资源管理器中打开文件夹.然后，在 File Explorer 的地址栏中键入 cmd 以在该文件夹中打开命令提示符.

Now that each DbContextFactory is created, you can start to create the migrations. Go to the folder for your class library. The easiest way it to right click the project and Open Folder in File Explorer. Then, type cmd in the address bar of the File Explorer to open a command prompt in that folder.

现在使用以下命令创建迁移:

Now use the following command to create the migration:

dotnet ef migrations add InitialCreate -c ApplicationDbContext --startup-project ../Migrations.Console/Migrations.Console.csproj

注意:更改 ApplicationDbContext 以匹配您正在使用的上下文的名称.此外，如果您使用其他名称调用控制台项目，则需要更改路径和名称.

Note: Change ApplicationDbContext to match the name of the context you are working with. Also, if you called the console project by another name, you will need to change the path and name.

您现在应该会在类库中看到一个 Migrations 文件夹.

You should now see a Migrations folder in your class library.

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