asp.net下拉控件的數據綁定列表

Question

早上好。 我有一個下拉列表控件，當選擇一個特定的項目時，另一個下拉列表將根據該選擇進行填充。後面的代碼如下。

Imports System.IO 
Partial Class Data 
Inherits System.Web.UI.Page 
Private Property _futureslist As List(Of String) 
Property FuturesList As List(Of String) 
    Get 
     Return _futureslist 
    End Get 
    Set(value As List(Of String)) 
     Dim strText As String = File.ReadAllText(HttpContext.Current.Server.MapPath("~/DataFiles/AvailableFutures.txt")) 
     Dim arytext() As String = strText.Split(",") 
     For i As Integer = 0 To arytext.Count - 1 
      value.Add(arytext(i)) 
     Next 
     _futureslist = value 
    End Set 

End Property 
Protected Sub ddlMain_SelectedIndexChanged(sender As Object, e As System.EventArgs) Handles ddlMain.SelectedIndexChanged 
    If Not IsPostBack Then 

     If ddlMain.SelectedItem.Text = "Futures" Then 
      ddlMainsub1.DataSource = _futureslist 
      ddlMainsub1.DataBind() 

     End If 
    End If 
End Sub 
End Class 

它正在讀取以創建列表屬性的文件格式如下; 玉米，小麥 ， 咖啡

所以當主下拉選擇的項目是「未來」的第二下拉值數據綁定到所述FuturesList屬性。任何幫助，將不勝感激

Answer 1

設置AutoPostBack=True 「ddlMain」，然後在

Protected Sub ddlMain_SelectedIndexChanged(sender As Object, e As System.EventArgs) Handles ddlMain.SelectedIndexChanged 
ddlMainsub1.Items.Clear() 
'bound items here to DropDownList2 
End Sub 

希望它幫助。祝你好運。