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我在兩個類之間創建了一個多對多的關係。EF 4.2代碼第一,如何刪除多對多的關聯?
public class Member
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid MemberId { get; set; }
public string Name { get; set; }
public virtual ICollection<Group> Groups { get; set; }
public Member()
{
Groups = new HashSet<Group>();
}
}
public class Group
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid GroupId { get; set; }
public string Name { get; set; }
public virtual ICollection<Member> Members { get; set; }
public Group()
{
Members = new HashSet<Member>();
}
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Group>().HasMany(x => x.Members).WithMany(c => c.Groups)
.Map(y =>
{
y.MapLeftKey("GroupId");
y.MapRightKey("MemberId");
y.ToTable("Group_to_Member");
});
}
這工作,如果我測試:
var member = new Member();
member.Name = "Smith";
db.Members.Add(member);
var group = new Group();
group.Name = "Group 1";
db.Groups.Add(group);
member.Groups.Add(group);
group.Members.Add(member);
db.SaveChanges();
但我怎樣才能刪除組成員?我嘗試過: var group = db.Groups.First(); db.Groups.Remove(group); db.SaveChanges();
我只是不斷收到「DELETE語句與REFERENCE約束衝突」。 那麼我怎麼能告訴它首先刪除關聯,然後輸入?
在您的數據庫中,將引用的屬性設置爲級聯刪除。 –
工作就像一個魅力。 – Patrick