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.

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");



        }



    }