asp.net - 实际上如何在 Entity Framework 4 Code-First CTP 5 中执行关系？

Question

我想要一个简短的示例来说明如何在 Entity Framework 4 Code-First CTP 5 中实际执行关系？

希望有一个此类关系的例子:

* one-to-many
* many-to-many

非常感谢!

Answer 1

一对一

public class One
{
  public int Id {get;set;}
  public virtual Two RelationTwo {get;set;}
}

public class Two
{
 public int Id {get;set;}
 public virtual One RelationOne {get;set;}
}

需要注意的是，它必须是虚拟的

一对多

public class One
{
  public int Id {get;set;}
  public virtual ICollection<Two> RelationTwo {get;set;}
}

public class Two
{
 public int Id {get;set;}
 public virtual One RelationOne {get;set;}
}

多对多

public class One
{
  public int Id {get;set;}
  public virtual ICollection<Two> RelationTwo {get;set;}
}

public class Two
{
 public int Id {get;set;}
 public virtual ICollection<One> RelationOne {get;set;}
}

注意它需要是 ICollection

以下链接可能有帮助，click和 click

希望这有帮助。

编辑

更新为包括一对多。

编辑#2

更新为包括执行评论所要求的发票<->产品场景的可能性。

注意:这尚未经过测试，但应该会让您朝着正确的方向

public class Invoice
{
    public int Id {get;set;}
    //.. etc. other details on invoice, linking to shipping address etc.

    public virtual ICollection<InvoiceProduct> Items {get;set;}
}

public class InvoiceProduct
{
    public int Id {get;set;}
    public int Quantity {get;set;}
    public decimal Price {get;set;} // possibly calculated
    //.. other details such as discounts maybe

    public virtual Product Product {get;set;}
    public virtual Invoice Order {get;set;} // maybe but not required
}

public class Product
{
    public int Id {get;set;}
    //.. other details about product
}

使用此功能，您可以遍历发票上的所有项目，然后 foreach 能够显示有关每个项目的发票详细信息以及产品本身的描述。