实体框架代码第一：如何在两个表之间创建一对多与一对一的关系？ [英] Entity Framework Code First: How can I create a One-to-Many AND a One-to-One relationship between two tables?

问题描述

这是我的模型：

public class Customer
{
    public int ID { get; set; }

    public int MailingAddressID { get; set; }
    public virtual Address MailingAddress { get; set; }

    public virtual ICollection<Address> Addresses { get; set; }
}

public class Address
{
    public int ID { get; set; }

    public int CustomerID { get; set; }
    public virtual Customer Customer { get; set; }
}

客户可以有任意数量的地址，但只有其中一个地址可以是一个邮寄地址。

A customer can have any number of addresses, however only one of those addresses can be a mailing address.

我可以获得一对一的关系，一对多的工作只要我使用一个，但是当我尝试引入两者我在地址表上获得了多个CustomerID密钥（CustomerID1，CustomerID2，CustomerID3）。

I can get the One to One relationship and the One to Many working just fine if I only use one, but when I try and introduce both I get multiple CustomerID keys (CustomerID1, CustomerID2, CustomerID3) on the Addresses table. I'm really tearing my hair out over this one.

为了映射一对一关系，我使用这里描述的方法 http://weblogs.asp.net/manavi/archive/2011/01/23/associations-in-ef-code-first-ctp5-part-3-one-to-one-foreign-key- associations.aspx

In order to map the One to One relationship I am using the method described here http://weblogs.asp.net/manavi/archive/2011/01/23/associations-in-ef-code-first-ctp5-part-3-one-to-one-foreign-key-associations.aspx

推荐答案

我几乎整天都在努力，当然我等待问在这之前，最终弄清楚了！

I've struggled with this for almost the entire day and of course I wait to ask here just before finally figuring it out!

除了在博客中演示的一对一之外，我还需要使用流畅的api来指定一般来说，由于一对一的关系不存在，所以多对多是不够的。

In addition to implementing the One to One as demonstrated in that blog, I also then needed to use the fluent api in order to specify the Many to Many since the convention alone wasn't enough with the One to One relationship present.

modelBuilder.Entity<Customer>().HasRequired(x => x.PrimaryMailingAddress)
    .WithMany()
    .HasForeignKey(x => x.PrimaryMailingAddressID)
    .WillCascadeOnDelete(false);

modelBuilder.Entity<Address>()
    .HasRequired(x => x.Customer)
    .WithMany(x => x.Addresses)
    .HasForeignKey(x => x.CustomerID);

这里是数据库中的最终模型：

And here is the final model in the database:

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