在使用实体框架，使用多个条件进行数据播种时，如何获取主键

Question

将Entity-Framework-6与MVC-5和Identity-framework-2结合使用。我想从第一个种子中找到主键，并将找到的密钥插入到第二个种子中。我使用多个条件来查找密钥，但不知何故我的Lambda表达式无法工作或未正确编写。

我遗漏了什么？

查看此处: /migrations/configurations.cs

我将使用这个示例https://stackoverflow.com/a/24936095/2910930作为其余seed的基础。

protected override void Seed(ApplicationDbContext context)
{
    bool itWorks = WriteReferenceData(context);
    base.Seed(context);
}

private bool WriteReferenceData(ApplicationDbContext ctx)
{
    DbContextTransaction transaction = null;
    bool succeeded = false;
    try
    {
        transaction = ctx.Database.BeginTransaction();

        CreateDetails(ctx);
        CreateRooms(ctx);

        ctx.SaveChanges();
        transaction.Commit();
        succeeded = true;
     }
     catch (Exception ex)
     {
         if (transaction != null) { transaction.Rollback(); transaction.Dispose(); }
         succeeded = false;
     }
     return succeeded;
}

在第一个种子，我将插入多个记录，主键是DB生成的。当我运行这个方法时，记录被正确插入并生成PK。

// FIRST SEED
private void CreateDetails(ApplicationDbContext ctx)
{
  var Details = new List<Detail>
  {
      new Detail { MaxUsers = 1, RoomName = "WorkRoom"},
      new Detail { MaxUsers = 2, RoomName = "WorkRoom"},
      new Detail { MaxUsers = 3, RoomName = "PlayRoom"}
  };
  Details.ForEach(s => ctx.Detail.AddOrUpdate(p => p.DetailID, s));
  ctx.SaveChanges();
}

// SECOND SEED
private void CreateRooms(ApplicationDbContext ctx)
{
    // THIS IS NOT WORKING CORRECTLY
    Int16 ID = ctx.Detail
                  .Single(x => 
                      x.RoomName == "WorkRoom" &&   
                      x.MaxUsers == 2).DetailID;

    var Rooms = new List<Room>
    {
        // 1 person
        new Room { RoomID = "X-16", DetailID = ID}
        new Room { RoomID = "X-17", DetailID = ID}
    };
    Rooms.ForEach(s => ctx.Room.AddOrUpdate(p => p.RoomID, s));
    ctx.SaveChanges();
}

Answer 1

在阅读了大量关于linq和Lambda的内容之后，答案比我想的要简单得多。

var detail = ctx.Detail.Where(x => x.DetailRoomName == "Patientroom" && x.MaxUsers == 1);

int detailID = detail.Single().DetailID;

var Rooms = new List<Room>
{
    // 1 person
    new Room { RoomID = "X-16", DetailID = detailID }
    new Room { RoomID = "X-17", DetailID = detailID }
};