EF Core外键配置问题代码优先问题

Posted 2023-02-16

【中文标题】EF Core外键配置问题代码优先问题

【英文标题】：EF Core Foreign Key configuration problem Code First Problem

【发布时间】：2022-01-01 06:28:51

【问题描述】：

我在应用中有 4 个表格。

User 表（来自 IdentityUser）-UserId 是 PK Club 表：PK 为 club_id。 必须属于Club 的Team 表。 PK 为team_id + club_id。 作为用户的表Player (PK UserID)。 必须属于一个团队的表Team_Players：PK 为team_id + club_id + UserId。

当我尝试添加迁移时，我收到以下错误：

具有外键属性 'Team_Id' : string 的从 'Team_Players.Team' 到 'Team' 的关系不能以主键 'Team_Id' : string, 'Club_Id' : string 为目标，因为它不兼容。为此关系配置一个主键或一组兼容的外键属性。

非常感谢您的帮助。

这是类的代码：

public class Club : BaseModel

        [Display(Name = "ID")]
        [Required]
        [Key]
        public string Club_id  get; set; 


public class Team : BaseModel

        [Display(Name = "ID")]
        [Required]
        public string Team_Id  get; set; 

        [ForeignKey("Club_Id")]
        public Club Club  get; set; 

        [Required]
        [Display(Name = "Club")]
        [MaxLength(50, ErrorMessage = "Field cannot be more than 50 Characters")]
        public string Club_Id   get; set; 
    

public class Player : BaseModel

        [Required]
        [Display(Name = "ID")]
        public string UserId  get; set; 
     
        [ForeignKey("Club_Id")]
        public Team Club  get; set; 

        [Required]
        [Display(Name = "Club ID")]
        [MaxLength(50, ErrorMessage = "Field cannot be more than 50 Characters")]
        public string Club_Id  get; set; 


public class Team_Players:BaseModel

        [Required]
        [Display(Name = "ID")]
        public string UserId  get; set; 

        [ForeignKey("Club_Id")]
        public Club Club  get; set; 

        [Display(Name = "Club ID")]
        [MaxLength(50, ErrorMessage = "Field cannot be more than 50 Characters")]
        public string Club_Id  get; set; 

        [ForeignKey("Team_Id")]
        public Team Team  get; set; 
        [Display(Name = "Team ID")]
        public string Team_Id  get; set; 

最后我的OnModelCreating 方法有以下代码：

modelBuilder.Entity<Team>()
                .HasKey(e => new  e.Team_Id, e.Club_Id);

modelBuilder.Entity<Coach>()
                .HasKey(e => new  e.UserId, e.Club_Id );

modelBuilder.Entity<Player>()
               .HasKey(e => new  e.UserId, e.Club_Id );

modelBuilder.Entity<Team_Players>()
               .HasKey(e => new  e.UserId, e.Club_Id ,e.Team_Id);

【参考方案1】：

外键以键为目标，而不仅仅是键的一部分。所以

[ForeignKey("Team_Id")]
public Team Team  get; set; 

应该是

[ForeignKey("Team_Id, Club_Id")]
public Team Team  get; set; 

因为

Entity<Team>().HasKey(e => new  e.Team_Id, e.Club_Id);