c# - Listing matching items in a combo box while entering a text? -

i have combobox in form , while user typing text in box, if there matching items in database text typed, should listed in combobox. user can notified if item being entered in database. i'm trying achieve follows.

when text entered in combo fire event. listening event, presenter matching user list database , list set datasource of combobox follows...

but why not displayed in combo? please let me know issue in code!

form

public partial class frmuser : form {     // 2 seperate , set properties used same combo box list set datasource.      public string username      {         get{return cmbusername.text;}     }      public ienumerable<user> userlist     {         set { cmbusername.datasource = value; }     }     private void cmbusername_textchanged(object sender, eventargs e)     {         onchangetext(sender, e);     } }  

presenter

class userpresenter {            private void wireupevents()     {         _view.onchangetext += new eventhandler(_view_onchangetext);     }      private void _view_onchangetext(object sender, eventargs e)     {         showmatchingusers();     }      private void showmatchingusers()     {         var userlist = _dataservice.getusers(_view.username ); //edit         _veiew.userlist = userlist; //edit     } } 

dataservice

    public ienumerable<user> getusers(string userid)     {          string selectstatement = "select user_id [user] user_id '@userid %'";         list<user> userlist = new list<user>();          using (var sqlconnection = new sqlconnection(db.connectionstring))          using (var sqlcommand = new sqlcommand(selectstatement, sqlconnection))         {             sqlcommand.parameters.add("@userid", sqldbtype.varchar).value = userid ;             sqlconnection.open();              using (sqldatareader datareader = sqlcommand.executereader())                  while (datareader.read())                 {                     userlist.add(                     new user                      {                         userid = (string) datareader["user_id"]                     });                 }              return userlist;          }     } 

i can't tell exactly how change code because missing quite few details, events , classes , possible nesting states of classes , objects.

but error is, noted, fact resulting ienumerable<user>which getusers brings thrown away.

you wrote should used datasource of combobox via property userlist in fact hiding property declaring new

list<user> userlist = new list<user>(); 

locally in getusers. ok, albeit little confusing; (i suggest call different newuserlist ;) still need set real userlist returned result set somewhere!

when patched (missing important info on actual code)

private void cmbusername_textchanged(object sender, eventargs e) {   userlist = _dataservice.getusers("_view.username");     ///onchangetext(sender, e); re-instate own wiring! } 

a dummy value showed fine in combobox..

you should not use code stay set up! changing

_dataservice.getusers(_view.username ); 

to

userlist = _dataservice.getusers(_view.username ); 

seems direct solution, have watch way connect innner , outer class variables..