asp.net - Update dropdown after Items.Clear() -

i populate dropdown several items. when user chooses 1 of these items, second dropdown gets populated.

when user clicks on "x" button on first dropdown, 2 dropdown must cleared. first dropdown gets cleared automatically, , clear second dropdown using "dropdown.items.clear()".

it happens when load again data first dropdown, second dropdown not update.

this code:

protected void dropdowndiagstati_selectedindexchanged(object sender, eventargs e)     {         int selectedindex = this.dropdowndiagstati.selectedindex;         populateddlstates(selectedindex);     }  private void populateddlstates(int selectedindex)     {         // ottengo diagrammi di stato in sessione         arraylist diagrammistato = session["statediagrams"] arraylist;          if(selectedindex > 0)         {             // ottengo il diagramma di stato selezionato             docspawr.diagrammastato currdiagstato = (docspawr.diagrammastato)diagrammistato[selectedindex - 1];              // ottengo gli stati del diagramma di stato selezionato             stato[] stati = currdiagstato.stati;              for(int = 0; < stati.length; i++)             {                 listitem item = new listitem();                  item.value = convert.tostring(stati[i].system_id);                 item.text = stati[i].descrizione;                  this.dropdownstati.items.add(item);                 this.uppanelstatiddl.update();             }         }         else         {             this.dropdownstati.items.clear();             this.uppanelstatiddl.update();         }     } 

i see old value in second dropdown , cannot select it.

you need remove update pane or can set data source drop-down.

ddl1.datasource = datasource; ddl1.datatextfield = "name"; ddl1.datavaluefield = "id"; ddl1.databind();