EF 4.1 - 模型关系

Question

我正在尝试使用RC版本的RS 4.1创建一个快速的ASP.NET MVC 3应用程序.我有两个型号:

public class Race
{
    public int RaceId { get; set; }
    public string RaceName { get; set; }
    public string RaceDescription { get; set; }
    public DateTime? RaceDate { get; set; }
    public decimal? Budget { get; set; }
    public Guid? UserId { get; set; }
    public int? AddressId { get; set; }

    public virtual Address Address { get; set; }
}

和

public class Address
{
    public int AddressId { get; set; }
    public string Street { get; set; }
    public string StreetCont { get; set; }
    public string City { get; set; }
    public string State { get; set; }
    public string ZipCode { get; set; }

    public virtual Race Race { get; set; }
}

尝试插入新Race时出现以下错误:

无法确定类型'rcommander.Models.Race'和'rcommander.Models.Address'之间关联的主要结束.必须使用关系流畅API或数据注释显式配置此关联的主要结尾.

它不应该自动将RaceId识别为Races表的主键和AddressId作为地址表的FK吗？我错过了什么吗？

谢谢!

Answer 1

这里的问题似乎是EntityFramework无法识别foreing键的位置,因为您在两个对象中都持有交叉引用.不确定你想要实现什么,我可能会建议这样的事情:

public class Race
{
  public int RaceId { get; set; }
  public string RaceName { get; set; }
  public string RaceDescription { get; set; }
  public DateTime? RaceDate { get; set; }
  public decimal? Budget { get; set; }
  public Guid? UserId { get; set; }

  public int? AddressId { get; set; }
  public virtual Address Address { get; set; }
}

public class Address
{
  public int AddressId { get; set; }
  public string Street { get; set; }
  public string StreetCont { get; set; }
  public string City { get; set; }
  public string State { get; set; }
  public string ZipCode { get; set; }
}

在第二个实体中跳过对Race的引用.

Answer 2

这里的问题是地址和种族之间的1:1关系!您可能希望将其映射为1:N,因此您需要将地址修改为:

public class Address
{
  public int AddressId { get; set; }
  public string Street { get; set; }
  public string StreetCont { get; set; }
  public string City { get; set; }
  public string State { get; set; }
  public string ZipCode { get; set; }

  public virtual ICollection<Race> Races { ... }
}

如果你想使用1:1然后你不能在Race中使用AddressId但Address中的AddressId必须是Race的外键,因为实体框架只能以1:1的方式"共享"主键.

Answer 3

对于一对一关系,您需要在第二个类中添加"[required]"属性.见下文:

public class Race
{
  public int RaceId { get; set; }
  public string RaceName { get; set; }
  public string RaceDescription { get; set; }
  public DateTime? RaceDate { get; set; }
  public decimal? Budget { get; set; }
  public Guid? UserId { get; set; }

  public int? AddressId { get; set; }
  public virtual Address Address { get; set; }
 }

public class Address
{
 public int AddressId { get; set; }
 public string Street { get; set; }
 public string StreetCont { get; set; }
 public string City { get; set; }
 public string State { get; set; }
 public string ZipCode { get; set; }

 [required]
 public Race Race { get; set; }

}

Answer 4

有一个好帖子:EF Code First CTP5中的关联:第2部分 - 共享主键关联

http://weblogs.asp.net/manavi/archive/2010/12/19/entity-association-mapping-with-code-first-one-to-one-shared-primary-key-associations.aspx