NET 6如何将AddDbContext注册代码迁移到Service静态扩展类

我在.NET 6项目的Program.cs文件中编写了如下数据库上下文注册代码：

var idConnectionString = builder.Configuration.GetConnectionString("IdentityConnection");

builder.Services.AddDbContext<ApplicationDbContext>(options => options.UseSqlServer(idConnectionString));

var abcConnectionString = builder.Configuration.GetConnectionString("abcConnection");
builder.Services.RegisterSqlServer<AbcDbContext>(abcConnectionString);

var xyzConnectionString = builder.Configuration.GetConnectionString("xyzConnection");
builder.Services.AddDbContext<XzyDbContext>(x => x.UseSqlServer(xyzConnectionString));

需要将上述数据库上下文注册代码迁移到自定义的Service扩展类中，现有扩展类结构如下：

public static class ServiceExtensions
{     
    public static IServiceCollection AddDbContextServices(this IServiceCollection services)
    {
        // 待填充注册逻辑
        return services;
    }
}

• 调整扩展方法签名，传入配置实例
  原注册逻辑依赖IConfiguration读取连接字符串，给扩展方法增加IConfiguration类型入参，把Program.cs中的注册逻辑直接平移到扩展方法内部即可，完整扩展类代码如下：

  using Microsoft.EntityFrameworkCore;
  // 引入项目中DbContext、自定义RegisterSqlServer扩展方法所在的命名空间
  
  public static class ServiceExtensions
  {     
      public static IServiceCollection AddDbContextServices(this IServiceCollection services, IConfiguration configuration)
      {
          // 注册ApplicationDbContext
          var idConnectionString = configuration.GetConnectionString("IdentityConnection");
          services.AddDbContext<ApplicationDbContext>(options => options.UseSqlServer(idConnectionString));
  
          // 注册AbcDbContext
          var abcConnectionString = configuration.GetConnectionString("abcConnection");
          services.RegisterSqlServer<AbcDbContext>(abcConnectionString);
  
          // 注册XzyDbContext
          var xyzConnectionString = configuration.GetConnectionString("xyzConnection");
          services.AddDbContext<XzyDbContext>(x => x.UseSqlServer(xyzConnectionString));
  
          return services;
      }
  }
  

• 替换Program.cs中的注册代码
  删除原来写在Program.cs里的零散DbContext注册代码，替换为一行扩展方法调用：

  builder.Services.AddDbContextServices(builder.Configuration);
  

注意：如果编译时提示找不到UseSqlServer、RegisterSqlServer方法或者各个DbContext类型，先检查命名空间引用：UseSqlServer需要引用Microsoft.EntityFrameworkCore以及SqlServer提供器包Microsoft.EntityFrameworkCore.SqlServer，自定义的RegisterSqlServer方法和各个DbContext需要引用项目内对应的命名空间。

内容的提问来源于stack exchange，提问作者Steve