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我在两个类之间创建了一个多对多的关系。EF 4.2代码第一,如何删除多对多的关联?
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");
});
}
这工作,如果我测试:
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();
但我怎样才能删除组成员?我尝试过: var group = db.Groups.First(); db.Groups.Remove(group); db.SaveChanges();
我只是不断收到“DELETE语句与REFERENCE约束冲突”。 那么我怎么能告诉它首先删除关联,然后输入?
在您的数据库中,将引用的属性设置为级联删除。 –
工作就像一个魅力。 – Patrick