使用linq2sql 的DetailView 如何保存多对多关系

比如有用户和角色这2个对象是多对多关系,而linq2sql是不支持多对多的,这个时候就要自己手工写代码了.

代码

public partial class frmUserEdit : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                if (Request["AddNew"] == "1")
                {
                    DetailsView1.DefaultMode = DetailsViewMode.Insert;
                    DetailsView1.AutoGenerateInsertButton = true;
                }
                else
                {
                    DetailsView1.DefaultMode = DetailsViewMode.Edit;

                }
                BindRoleList();
            }
        }

        private void BindRoleList()
        {
            CheckBoxList cblRole = DetailsView1.FindControl("cblRole") as CheckBoxList;
            cblRole.DataTextField = "RoleName";
            cblRole.DataValueField = "RoleID";
            cblRole.DataSourceID = RolesDataSource.ID;
            cblRole.DataBind();
        }
        private List<long> GetSelectedRoles()
        {
            CheckBoxList cblRole = DetailsView1.FindControl("cblRole") as CheckBoxList;
            List<long> result = new List<long>();
            foreach (ListItem item in cblRole.Items)
            {
                if (item.Selected)
                    result.Add(long.Parse(item.Value));
            }
            return result;
        }

        //roles data bound,check many-to-many to check/uncheck selected
        protected void cblRole_DataBound(object sender, EventArgs e)
        {
            User usr = DetailsView1.DataItem as User;
            if (null == usr) return;

            CheckBoxList cblRole = sender as CheckBoxList;
            foreach (Role r in usr.RoleList)
            {
                foreach (ListItem item in cblRole.Items)
                {
                    if (r.RoleID.ToString() == item.Value)
                        item.Selected = true;
                }
            }
        }

        }
        private void ShowMsg(string ExceptionMsg)
        {
            lblErr.Text = ExceptionMsg;
        }

        protected void DetailsView1_ItemUpdating(object sender, DetailsViewUpdateEventArgs e)
        {
            User usr = new User();
            usr.UserID = long.Parse(Request["ID"]);
            usr.UserName = e.NewValues["UserName"].ToString();
            UserService.Save(usr, GetSelectedRoles(), false);
            e.Cancel = true;
            ShowMsg("Save Successfully");

        }

    }