One-to-Zero/One 和 Entity Framework 中的一对多关系 5

Question

我 google 很苦恼，但无法完全理解，here 我发现有用的信息很少，但没有成功。下面是我的问题，

我有以下类并且需要一种方法来指定实体模型中的关系。

public class User
{
    [Key]
    public int UserId { get; set; }
    public int? HomeAddressId { get; set; }

    public virtual ICollection<Address> Addresses { get; set; }
    public virtual Address HomeAddress{ get; set; }
}
public class Address
{
    [Key]
    public int AddressId { get; set; }
    public int UserId { get; set; }
    public string AddressLine1 { get; set; } 

    // other properties
    public virtual User User { get; set; }
}

要求是每个用户有多个地址，每个地址与一个用户关联（一对多）。地址之一是家庭地址，因此用户有家庭地址（可选）。 HomeAddressId 是地址 table 的 FK（可为空）。我如何首先在实体模型代码中定义这种关系，最好是在 Fluent API 方法中？

Answer 1

我更喜欢以简单的方式展示代码。

   public class User
    {
        [Key]
        public int UserId { get; set; }
        public int? HomeAddressId { get; set; }

        public virtual ICollection<Address> Addresses { get; set; }
        public Address HomeAddress { 
           get {
                if(Addresses != null)
                   return Addresses.FirstOrDefault(p=> p.AddressType.Home);
                return null;
           }
        }
    }
    public enum AddressType
    {
        Unknown,
        Home,
        Office
    }
public class Address
{
    [Key]
    public int AddressId { get; set; }
    public int UserId { get; set; }
    public string AddressLine1 { get; set; } 
    public AddressType AddressType {get; set; }

    // other properties
    public virtual User User { get; set; }
}

第二流利。

public class User
{
     public int UserId { get; set; }
     public virtual Address HomeAddress { get; set; }
     public virtual int? HomeAddressId { get; set; }
     public virtual ICollection<Address> OfficeAddresses { get; set; }
}

public class Address
{
     public int AddressId { get; set; }
     public string AddressLine1 { get; set; } 
}

public class UserMap : MapEntityTypeConfiguration<User>
{
     public UserMap ()
     {
        //Other definitions PK etc...

        this.HasOptional(o => o.HomeAddress)
                .WithMany()
                .HasForeignKey(a => a.HomeAddressId);

        this.HasMany(t => t.OfficeAddresses)
          .WithMany()
          .Map(m =>
          {
              m.ToTable("UserOfficeAddresses");
              m.MapLeftKey("AddressId");
              m.MapRightKey("UserId");
          });
     }
}
//and define Address Configurations.. MapEntityTypeConfiguration<Address>

One-to-Zero/One 和 Entity Framework 中的一对多关系 5

Both One-to-Zero/One and One-to-Many relation in Entity Framework 5

c#

one-to-one

one-to-many

ef-code-first

entity-framework-5