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DropDownList selectedindex = -1 after postback

Posted on 2008-06-19
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Last Modified: 2010-04-21
Hi Experts,

The dropdownlist (DDL1) on my aspx page gets populated on page load just fine. On page load I set the selectedindex to 1.

I have Autopostback set to false on the dropdownlist.

When I click on a button, and go to the function behind that button click Updatebtn_Click(), I want to retrieve the selected item in DDL1. However, at this point I get an object reference error and DDL1.selectedindex = -1.

Could you tell me what's going on and how I can get the selected value without a flash on the page?

Here's the aspx:
Dropdownlist:
<asp:DropDownList AutoPostBack="false" ID="DDL1" runat="server" Font-Size="X-Small" width="120"></asp:DropDownList>

Button:
<asp:Button ID="Updatebtn" runat="server" Text="Update" Font-Size="1.0em" OnClick="Updatebtn_Click" />

The page has enableviewstate set to false.


Here's the code behind:

protected void Page_Load(object sender, EventArgs e)
    {

        if (!Page.IsPostBack && !Page.IsCallback)
        {

            InitAlertsPanel();

            DataTable dt = (DataTable)Session["dataTable"];
            grid1.DataSource = dt;
            grid1.KeyFieldName = "RowNumber";
            grid1.DataBind();


            // Register trigger for update panel
            ScriptManager1.RegisterAsyncPostBackControl(Button1);
            AsyncPostBackTrigger trigger = new AsyncPostBackTrigger();
            trigger.EventName = "Click";

            if (Button1.UniqueID.EndsWith(trigger.ControlID))
            {
                trigger.ControlID = Button1.UniqueID.ToString();
            }

        }
        else
        {
            //Bind the grid on every request
            BuildGrid1();


        }

        if (!IsPostBack){
            GetUPendingStatus(); // This populates DDL1

        }

0
Comment
Question by:rss2
3 Comments
 
LVL 16

Expert Comment

by:burakiewicz
ID: 21823659
to get it form the codebehind you need it to postback, if you can use ajax then you could put the ddl in an update panel, and you wont see the screen flash
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LVL 37

Accepted Solution

by:
samtran0331 earned 2000 total points
ID: 21824233
>>The page has enableviewstate set to false.

ViewState is what holds the values of controls.
Try either enabling viewstate on the entire page or just on the dropdownlist.
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Author Closing Comment

by:rss2
ID: 31468860
Thank you SO MUCH!!! :)
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