实体框架中的1：1关系 [英] 1:1 relationship in Entity framework

问题描述

我需要在实体框架中 ApplicationUser 和我自己的类之间的1：1关系。

I need 1:1 relationship between ApplicationUser and my own class in entity framework.

我这样做：

public class ApplicationUser : IdentityUser
{
    public async Task<ClaimsIdentity> GenerateUserIdentityAsync(UserManager<ApplicationUser> manager)
    {
        var userIdentity = await manager.CreateIdentityAsync(this, DefaultAuthenticationTypes.ApplicationCookie);
        return userIdentity;
    }

    /*Realations*/

    public virtual ICollection<Comment> Comments { get; set; }
    public virtual Posts Post { get; set; }
}


public class Posts : System.Object
{
    public Posts()
    {
        this.PostDate = DateTime.Now;
        this.PostViews = 0;
        this.PostPic = "d.jpg";
    }

    [Key]
    public int PostID { get; set; }

    public string PostName { get; set; }
    public string PostSummery { get; set; }
    public string PostDesc { get; set; }
    public string PostPic { get; set; }
    public DateTime PostDate { get; set; }
    public int PostViews { get; set; }
    public string postMetaKeys { get; set; }
    public string PostMetaDesc { get; set; }


    public string UserId { get; set; }
    [Key, ForeignKey("UserId")]
    public virtual ApplicationUser ApplicationUser { get; set; }


    public int CategoryID { get; set; }
    [Key, ForeignKey("CategoryID")]
    public virtual Categories Category { get; set; }

    public virtual ICollection<Comment> commnets {get; set;}
}

但是当我写命令add -migration关系在 Nuget 控制台内。

But I am getting an exception when I write the command "add-migration relation" inside Nuget console.

无法确定
类型的FinalKaminet.Models.ApplicationUser和Models.Posts之间的关联。必须使用
显式配置此关联的
主体结尾，即关联流畅的API或数据注释。

Unable to determine the principal end of an association between the types 'FinalKaminet.Models.ApplicationUser' and 'Models.Posts'. The principal end of this association must be explicitly configured using either the relationship fluent API or data annotations.

我还在 IdentityModels 中添加以下代码，但是显示了另一个错误：

I also add below code inside IdentityModels, but another error was shown:

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder); 


        modelBuilder.Entity<ApplicationUser>()
        .HasOptional(f => f.Post)
        .WithRequired(s => s.ApplicationUser);
    }

在模型中检测到一个或多个验证错误一代：

One or more validation errors were detected during model generation:

ApplicationUser_Post_Target：：在ApplicationUser_Post关系中的角色
'ApplicationUser_Post_Target'中，多项式无效。
由于从属角色属性不是关键属性，因此从属角色的多重性的
上界必须为'*'。

ApplicationUser_Post_Target: : Multiplicity is not valid in Role 'ApplicationUser_Post_Target' in relationship 'ApplicationUser_Post'. Because the Dependent Role properties are not the key properties, the upper bound of the multiplicity of the Dependent Role must be '*'.

有什么问题？

推荐答案

你想要1到1的用户和帖子之间的关系？一个用户只能发布一个而且只发布？

you want a 1 to 1 relation between user and post ? A user can only post one, and only, post ?

无论如何，在EF（至少6）中，可以在共享相同的两个实体之间建立1到1的关系PK。那就是PK是FK。所以你必须将帖子的PK设置为一个字符串。

Anyway, in EF (at least 6) a 1 to 1 relation can be established between two entities sharing the same PK. That is the PK is the FK. So you must set the PK of posts as a string.

否则你处于1到*关系。

Otherwise you are in a 1 to * relation.

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