如何使用 Entity Framework 4 Code First (POCO) 声明一对一关系 [英] How to declare one to one relationship using Entity Framework 4 Code First (POCO)

查看:38
本文介绍了如何使用 Entity Framework 4 Code First (POCO) 声明一对一关系的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

如何使用实体框架 4 代码优先 (POCO) 声明一对一关系?

How to declare a one to one relationship using Entity Framework 4 Code First (POCO)?

我发现了这个问题(一个-实体框架 4 中的一对一关系),但答案引用的文章没有用(有一行代码是 1-1 关系,但没有提到如何定义它).

I found this question (one-to-one relationships in Entity Framework 4) , but the article that the answer references was not useful (there is one line of code that is a 1-1 relationship, but no mention of how to define it).

推荐答案

你只是在寻找这样的东西吗?

Are you just looking for something like this?

public class User
{
    public int Id { get; set; }
    public string Username { get; set; }
    public Profile Profile { get; set; }
    public int ProfileId { get; set; }
}

public class Profile
{
    public int Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string PostalCode { get; set; }
    // etc...
}

public class UserMapping : EntityConfiguration<User>
{
    public UserMapping()
    {
        this.HasKey(u => u.Id);
        this.Property(u => u.Username).HasMaxLength(32);

        // User has ONE profile.
        this.HasRequired(u => u.Profile);
    }
}

public class ProfileMapping : EntityConfiguration<Profile>
{
    public ProfileMapping()
    {
        this.HasKey(p => p.Id);
        this.Property(p => p.FirstName).HasMaxLength(32);
        this.Property(p => p.LastName).HasMaxLength(32);
        this.Property(p => p.PostalCode).HasMaxLength(6);
    }
}

EDIT:是的,我面前没有 VS,但您需要在 UserMapping 中添加以下行而不是当前的 HasRequired 并添加一个 ProfileId 属性(而不是您添加的 Profile_Id):

EDIT: Yeah I didn't have VS in front of me but you need to add the following line in the UserMapping instead of the current HasRequired and also add a ProfileId property (instead of Profile_Id that you added):

this.HasRequired(u => u.Profile).HasConstraint((u, p) => u.ProfileId == p.Id);

我目前认为没有办法解决这个问题,但我相信它会改变,因为我们只在 CTP4 中.如果我能说:

I currently don't think there's a way around this, but I'm sure it'll change since we're only in CTP4. It'd be nice if I could say:

this.HasRequired(u => u.Profile).WithSingle().Map(
    new StoreForeignKeyName("ProfileId"));

这样我就不必包含 ProfileId 属性.也许目前有一种方法可以解决这个问题,但我仍然要在清晨思考:)

This way I wouldn't have to include a ProfileId property. Maybe there is a way around this currently and it's still to early in the morning for me to think :).

如果你想包含一个导航属性",还记得调用 .Include("Profile").

Also remember to call .Include("Profile") if you want to include a "navigational property".

这篇关于如何使用 Entity Framework 4 Code First (POCO) 声明一对一关系的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!

查看全文
登录 关闭
扫码关注1秒登录
发送“验证码”获取 | 15天全站免登陆