C# EF 4.2代码首先,如何删除多对多关联?
我在两个类之间创建了多对多关系C# EF 4.2代码首先,如何删除多对多关联?,c#,entity-framework,entity-framework-4,ef-code-first,fluent-interface,C#,Entity Framework,Entity Framework 4,Ef Code First,Fluent Interface,我在两个类之间创建了多对多关系 public class Member { [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public Guid MemberId { get; set; } public string Name { get; set; } public virtual ICollection<Group> Groups { get; set; } public
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");
});
}
但如何从组中删除成员?
我试过这个:
var group=db.Groups.First();
db.Groups.Remove(组);
db.SaveChanges()
我只是不断得到“DELETE语句与引用约束冲突”。
那么,我如何告诉它先删除关联,然后删除条目?请参阅RedHat关于将数据库中的FK设置为删除时级联的评论。在数据库中,将引用的属性设置为删除时级联。
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();