Solved

DropDownList selectedindex = -1 after postback

Posted on 2008-06-19
3
3,898 Views
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
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
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
0
 
LVL 37

Accepted Solution

by:
samtran0331 earned 500 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.
0
 

Author Closing Comment

by:rss2
ID: 31468860
Thank you SO MUCH!!! :)
0

Featured Post

Free Tool: Port Scanner

Check which ports are open to the outside world. Helps make sure that your firewall rules are working as intended.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction Hi all and welcome to my first article on Experts Exchange. A while ago, someone asked me if i could do some tutorials on object oriented programming. I decided to do them on C#. Now you may ask me, why's that? Well, one of the re…
A quick way to get a menu to work on our website, is using the Menu control and assign it to a web.sitemap using SiteMapDataSource. Example of web.sitemap file: (CODE) Sample code to add to the page menu: (CODE) Running the application, we wi…
Finds all prime numbers in a range requested and places them in a public primes() array. I've demostrated a template size of 30 (2 * 3 * 5) but larger templates can be built such 210  (2 * 3 * 5 * 7) or 2310  (2 * 3 * 5 * 7 * 11). The larger templa…
How to Install VMware Tools in Red Hat Enterprise Linux 6.4 (RHEL 6.4) Step-by-Step Tutorial

734 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question