为什么 entity framework 试图删除删除时的关联行？

Question

所以我得到了这个代码：

...
     modelBuilder.Entity<Person>(builder => {
           builder.ToTable("person");
           builder.Property(x => x.PersonId).HasColumnName("nconst");
           builder.Property(x => x.FirstName).HasColumnName("firstname");
           builder.Property(x => x.LastName).HasColumnName("lastname");
           builder.Property(x => x.BirthYear).HasColumnName("birthyear");
           builder.HasKey(x => x.PersonId);
           builder.HasMany(x => x.Works).WithOne().HasForeignKey(x => x.PersonId);
           builder.HasOne(x => x.Death).WithOne().HasForeignKey<Death>(x => x.PersonId);
     });

     modelBuilder.Entity<PersonBookmark>(builder => {
          builder.ToTable("personbookmark");
          builder.Property(x => x.PersonId).HasColumnName("nconst");
          builder.Property(x => x.UserId).HasColumnName("user_id");
          builder.Property(x => x.Date).HasColumnName("date");
          builder.Property(x => x.Label).HasColumnName("label");
          builder.HasKey(x => new { x.UserId, x.PersonId });
          builder.HasOne(x => x.User).WithMany(x => x.PersonBookmarks).HasForeignKey(x => x.UserId);
          builder.HasOne(x => x.Person).WithOne().HasPrincipalKey<PersonBookmark>(x => x.PersonId).HasForeignKey<Person>(x => x.PersonId);
     });
...

namespace DataService.Domain {

    public class PersonBookmark {

        public int UserId { get; set; }

        public DateTime Date { get; set; }

        [StringLength(100, MinimumLength = 1)]
        public string Label { get; set; }

        [StringLength(10, MinimumLength = 10)]
        public string PersonId { get; set; }


        [NotMapped]
        public virtual User User { get; set; }

        [NotMapped]
        public virtual Person Person { get; set; }
    }
}

namespace DataService.Domain {

    public class Person {

        public Person() {
            Works = new HashSet<Work>();
        }

        [StringLength(10, MinimumLength = 10)]
        public string PersonId { get; set; }

        [StringLength(100, MinimumLength = 1)]
        public string LastName { get; set; }

        [StringLength(100, MinimumLength = 1)]
        public string FirstName { get; set; }

        [StringLength(4, MinimumLength = 4)]
        public string BirthYear { get; set; }


        [NotMapped]
        public virtual ICollection<Work> Works { get; set; }

        [NotMapped]
        public virtual Death Death { get; set; }
    }
}

public bool DeletePersonBookmark(int UserId, string PersonId) {
    var personBookmark = Context.PersonBookmarks.FirstOrDefault(x => x.UserId == UserId && x.PersonId == PersonId);
     var found = personBookmark != null;

     if (found) {
          Context.PersonBookmarks.Remove(personBookmark);
          Context.SaveChanges();
     }

     return found;
}

当我试图从数据库中删除 PersonBookmark 时，我遇到了这个异常：

Microsoft.EntityFrameworkCore.DbUpdateException : An error occurred while updating the entries. See the inner exception for details.
---- Npgsql.PostgresException : 23503: update or delete on table "person" violates foreign key constraint "personbookmark_nconst_fkey" on table "personbookmark"

看起来 entity framework 正试图删除关联的 Person 行，但我不知道我在哪里告诉他这样做... 我只想删除 PersonBookmark 行。也许我不明白一些明显的事情，但在我看来 Person 影子属性并不意味着关联的 Person 应该与其引用所有者一起消失。

有人可以帮助我吗？

提前致谢

Answer 1

It looks like entity framework is trying to remove the associated Person row, but I don't know where I told him to do this...

就在这里

builder.HasOne(x => x.Person).WithOne()
   .HasPrincipalKey<PersonBookmark>(x => x.PersonId) // <--
   .HasForeignKey<Person>(x => x.PersonId);

对于一对一关系，HasPrincipalKey / HasForeignKey 的通用类型参数用于指定谁是 principal 以及谁是依赖关系 (docs)。并且级联删除从主体到依赖方向工作，即删除主体级联删除依赖项。

这里需要的是交换Person和PersonBookmark角色：

builder.HasOne(x => x.Person).WithOne()
   .HasPrincipalKey<Person>(x => x.PersonId)
   .HasForeignKey<PersonBookmark>(x => x.PersonId);

确保重新生成迁移并将其应用到数据库。

为什么 entity framework 试图删除删除时的关联行？

Why is entity framework trying to delete the associated row on delete?

c#

entity-framework

entity-framework-core