如何创建有2个引用到另一个类POCO对象 [英] How do I create a POCO object that has 2 references to another class

问题描述

我有一个表（事件），可以有2个位置（主，备用）。位置可以在其它表中（所以在locationTable无事件ID）使用POCO自跟踪，我怎么创建从事件表到位置表，或什么是处理这种情况的最好方法参考使用（我有一个总的脑冻过这一点）？ （.NET 4.0 C＃，EF4.1，MVC 3中使用）。

I have a table (Event) that can have 2 Locations (main, alternate). Locations can be used in other tables (so no EventId in the locationTable) Using POCO self-tracking, how do I create the reference from the Event table to the Locations table, or what is the best way to handle this situation (I'm having a total brain freeze over this)? (.NET 4.0 C#, EF4.1, MVC 3 being used).

简体类：

public class Event
{
   public int EventId {get; set;}
   public string Tile {get; set;}
   public int MainLocationId {get; set;}
   public int AltLocationId {get; set;}

   public virtual ICollection<Location> EventLocations {get; set;}
}

public class Location
{
   public int LocationId {get; set;}
   public string Name {get; set;}
}

我想每个表和指示，如果它是主要的或ALT位置的标志PK的链接表（EventLocations），但我不知道如何做到这一点看在POCO类设置。也许这一点，但它需要额外的业务逻辑（我最终希望能够将这一王解成T4，所以我不必在今后的项目添加业务逻辑）：

I was thinking a linking table (EventLocations) with the PK of each table and a flag indicating if it's the main or alt location, but I'm not sure how this would look in a POCO class setup. Maybe this, but it requires extra business logic (and I ultimately would like to be able to incorporate this king of solution into a T4 so I don't have to add business logic in future projects):

public class Event
{
   public int EventId {get; set;}
   public string Tile {get; set;}

   public virtual ICollection<EventLocation> EventLocations {get; set;}
}

public class Location
{
   public int LocationId {get; set;}
   public string Name {get; set;}

   public virtual ICollection<EventLocation> EventLocations {get; set;}
}

public class EventLocation
{
   public int EventId {get;set;}
   public int LocationId {get;set;}
   public bool IsMain {get; set;}

   public virtual Event Event {get;set;}
   public virtual Location Location {get;set;}
}

感谢您的任何建议/提示/解决方案/建设性的批评！

Thanks for any advice/ tips/ solutions/ constructive criticism!

推荐答案

最简单的方法就是使用：

The simplest way is simply using:

public class Event
{
   public int EventId {get; set;}
   public string Tile {get; set;}
   public int MainLocationId {get; set;}
   public int AltLocationId {get; set;}

   public virtual Location MainLocation {get; set;}
   public virtual Location AlternativeLocation {get; set;}

   // You can also add Foreign key properties for locations to simplify some usage scenarios
}

public class Location
{
   public int LocationId {get; set;}
   public string Name {get; set;}
}

您有那么使用多个一对多关系可能不是需要（它可能会意外地增加更多位置，在事件）为您的活动定义的位置确切数字。

You have exact number of locations defined for your event so using many-to-many relation is probably not needed (it can accidentally add more locations to your Event).

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