為什么物體框架試圖在洗掉時洗掉關聯的行？

所以我有這個代碼：

...
     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;
}

當我試圖PersonBookmark從資料庫中洗掉 a 時，我遇到了這個例外：

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"

看起來物體框架正在嘗試洗掉關聯的Person行，但我不知道我在哪里告訴他這樣做的......我只想PersonBookmark洗掉該行。也許我不明白一些明顯的東西，但在我看來，Person影子屬性并不意味著關聯Person應該與其參考所有者一起消失。

有人能幫我嗎？

先感謝您

uj5u.com熱心網友回復：

看起來物體框架正試圖洗掉關聯的 Person 行，但我不知道我在哪里告訴他這樣做的......

就在這兒

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

對于一對一關系，HasPrincipalKey/的泛型型別引數HasForeignKey用于指定關系中誰是主體，誰是從屬關系 ( docs )。級聯洗掉從主體到依賴方向，即洗掉主體級聯洗掉依賴。

你在這里需要的是交換Person和PersonBookmark角色：

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

確保重新生成遷移并將其應用到資料庫。

標籤：C＃ 实体框架 实体框架核心

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