ASP.Net dropdownlist not returning index on selectedindexchanged event

Question

I have a dropdownlist control with a selectedindexchanged event that fires correctly. However, when you select an item from the list the index value that is returned to the selectedindexchanged event does not change; the list box pops back tot the first item in the list.

ASP DROP DOWN LIST CONTROL:

 <asp:DropDownList ID="CuisineList" runat="server" Width="100" 
    AutoPostBack = "true" onselectedindexchanged="CuisineList_SelectedIndexChanged" >
 </asp:DropDownList>

DATA BOUND TO CONTROL IN PAGELOAD EVENT:

 protected void Page_Load(object sender, EventArgs e)
 {
    //Load drop down lists for restaurant selection

    BLgetMasterData obj = new BLgetMasterData();

    var cusineList = obj.getCuisines();
    CuisineList.DataSource = cusineList;
    CuisineList.DataBind();
    CuisineList.Items.Insert(0, "Any");

SELECTEDINDEXCHANGEDEVENT:

   protected void CuisineList_SelectedIndexChanged(object sender, EventArgs e)
   {
       if (IsPostBack)
       {
           string def = this.CuisineList.SelectedItem.Value;
           //ALWAYS returns index '0'
       }
   }

How are you triggering the event? Are you using the keyboard or mouse? Believe it or not, I've run into problems where one method works and the other does not! — NickAldwin
– NickAldwin, Commented Jun 27, 2011 at 15:20
What is the value bound to? If the value is always zero, then selected item will be the first one in the list with value = 0 - i.e. 'Any'. — Jackson Pope
– Jackson Pope, Commented Jun 27, 2011 at 15:20

Off The Gold · Accepted Answer · 2016-02-15 14:48:06Z

17

You need to put your Dropdownlist binding code under !IsPostBack() in the page_load event. like...

protected void Page_Load(object sender, EventArgs e) { 
 if(!IsPostBack)
 {
  BLgetMasterData obj = new BLgetMasterData();

  var cusineList = obj.getCuisines();
  CuisineList.DataSource = cusineList;
  CuisineList.DataBind();
  CuisineList.Items.Insert(0, "Any");
 }
}

Reason: Whenever your SelectedIndex Change Event fires, the Page_load event is called before the SelectedIndex Change event and your dropdown data rebinded, that's why your currect selection was lost.

edited Feb 15, 2016 at 14:48

Off The Gold

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answered Jun 27, 2011 at 15:20

Muhammad Akhtar

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