. NET MVC DropDownList drop-down box _ Infinite class classification

1. Database design:
Id:int
Name:string
Pid:int//Parent ID (the top-level menu defaults to 0)

2. Controller:

Using system;using system.collections.generic;using system.linq;using system.web;using System.Web.Mvc;using        Mvctest.models;namespace mvctest.controllers{[ValidateInput (false)] public class Homecontroller:controller {        Private Testentities db = new testentities ();            [Loginfilter] public ActionResult Index () {binddropdownlist ();        return View (); }//Bind top-level classification private void Binddropdownlist () {list<selectlistitem> Select1 = n            EW list<selectlistitem> (); var one = from C in db.            Categories where c.pid = = 0 Select C;                foreach (Var b in one) {string name = B.name; string id = b.id.tostring (); Select1.                ADD (new SelectListItem {Text = ">" + name, Value = ID                }); int sonparentpid = Int.                Parse (ID);          string blank = "┠";      Recursive sub-classification method Bindnode (Sonparentid, blank, Select1);        } viewbag.calist = new SelectList (Select1, "Value", "Text");            }//bound sub-classification private void Bindnode (int pid, string blank, list<selectlistitem> select1) { var = db.            Categories.where (c = c.pid = = pId);                foreach (var c in) {string zname = blank + c.name;                String zid = C.id.tostring (); Select1.                 ADD (new SelectListItem {Text = zname, Value = Zid}); int sonparentid = Int.                Parse (Zid);                String blank2 = blank + "-";            Bindnode (Sonparentid, BLANK2, Select1); }        }    }}

3. View:

@Html. dropdownlistfor (A = A.caid, viewbag.calist as IENUMERABLE<SELECTLISTITEM>,---Please select---, new {style = "wi dth:120px; "})

. NET MVC DropDownList drop-down box _ Infinite class classification