Lambda 递归获取所有子节点

实体结构：

public class Sys_Menu
{
public string MenuCode { get; set; }

public string MenuDesc { get; set; }

public string ParentCode { get; set; }
}

　　

 

/// <summary>
        /// 获取current所有子级
        /// </summary>
        /// <param name="list"></param>
        /// <param name="current"></param>
        /// <returns></returns>

        public static List<Sys_Menu> GetChildren(List<Sys_Menu> list, Sys_Menu current)
        {
            var query = list.Where(x => x.ParentCode == current.MenuCode).ToList();
            return query.Concat(query.SelectMany(t => GetChildren(list, t))).ToList();

        }

        /// <summary>
        /// 获取current的所有父级
        /// </summary>
        /// <param name="list"></param>
        /// <param name="current"></param>
        /// <returns></returns>
        public static List<Sys_Menu> GetParents(List<Sys_Menu> list, Sys_Menu current)
        {
            var query = list.Where(x => x.MenuCode == current.ParentCode).ToList();
            return query.Concat(query.SelectMany(t => GetParents(list, t))).ToList();

        }

　　测试代码：

Sys_Menu menu = new Sys_Menu { MenuCode = "01", MenuDesc = "根节点", ParentCode = null };



            Sys_Menu menu1 = new Sys_Menu { MenuCode = "02", MenuDesc = "系统管理", ParentCode = "01" };
            Sys_Menu menu2 = new Sys_Menu { MenuCode = "03", MenuDesc = "用户管理", ParentCode = "02" };
            Sys_Menu menu3 = new Sys_Menu { MenuCode = "04", MenuDesc = "角色管理", ParentCode = "02" };

            Sys_Menu menu4 = new Sys_Menu { MenuCode = "05", MenuDesc = "基础数据", ParentCode = "01" };



            List<Sys_Menu> menuList = new List<Sys_Menu>();
            menuList.Add(menu);
            menuList.Add(menu1);
            menuList.Add(menu2);
            menuList.Add(menu3);
            menuList.Add(menu4);

            Expression<Func<Sys_Menu, Sys_Menu, bool>> tt = (x, y) => x.MenuCode == y.ParentCode;

            List<Sys_Menu> parents = new List<Sys_Menu>();
            TreeUtil.GetParents(menuList, menu3, "MenuCode","ParentCode", parents);

            List<Sys_Menu> children = new List<Sys_Menu>();
            TreeUtil.GetChildren(menuList, menu1, "MenuCode", "ParentCode", children);

            var mm = GetChildren(menuList, menu);

            var mm1 = GetParents(menuList, menu3);

            Console.ReadKey();