CODEWITHSUNDEEP
asp.netdrop-down-menu
rlcrews
rlcrews

Reputation: 3562

How to set the selected value and text of a drop down menu on page load with asp.net

within an asp.net page I have a predefined drop down menu

<asp:DropDownList CssClass="queryterm dropdownSpacer" ID="ddResultNum" runat="server">
     <asp:ListItem Text="10 Results " Value="10" />
     <asp:ListItem Text="20 Results" Value="20" />
     <asp:ListItem Text="30 Results" Value="30" />
     <asp:ListItem Text="40 Results" Value="40" />
     <asp:ListItem Text="50 Results" Value="50" />
     <asp:ListItem Text="100 Results" Value="100" />
</asp:DropDownList>

In the code behind I am trying to set the selected value based upon a query to the database.

protected void SetResultsDropDown()
        {
            string selectCommand = String.Format("SELECT ResultsReturned FROM StoredFilters WHERE SecurityUserID = {0}", securityUserId);
            string resultValue = DatabaseUtilities.QueryDatabase(selectCommand, ConfigurationManager.AppSettings["informconnectstring"].ToString(), "ResultsReturned");
           //based upon the users id the db stores the set number from the drop down the default is 10 however if the number changes when the page loads I want the user to see what their current result set being returned is in the drop down vs. it defaulting to the first option
            ddResultNum.ClearSelection();
            switch (resultValue)
            {
                case "10":   
                    ddResultNum.Items[0].Selected = true; 
                    break;
                case "20":
                    ddResultNum.Items[1].Selected = true; 
                    break;
                case "30":
                    ddResultNum.Items[2].Selected = true;
                    break;
                case "40":
                    ddResultNum.Items[3].Selected =true;
                    break;
                case "50":
                    ddResultNum.Items[4].Selected = true;
                    break;
                case "100":
                    ddResultNum.Items[5].Selected = true;
                    break;
            }
        }

I have tried calling this method using onInit as well as during the page load

protected override void OnInit( EventArgs e)
        {
            base.OnInit(e);
            // Extract an Inform User ID from the Token.
            IClaimsIdentity claimsIdentity = ((IClaimsPrincipal)(Thread.CurrentPrincipal)).Identities[0];
            securityUserId = Convert.ToInt64(claimsIdentity.Claims.Where(c =>
                c.ClaimType == AuthenticationConstants.INFORM_USER_ID_CLAIM_TYPE).First().Value);

            SetResultsDropDown();
        }

While the switch steps through and updates object I never see the text within the drop down menu update. It always stays set to the first item of 10 results.

I have tried wrapping the control in an udpatepanel and then calling an update on the panel to see if I could force the refresh on render and page load.

I have also tried instead of using Items[0].Selected I have tried to set the selected index as:

protected void SetResultsDropDown()
{
string selectCommand = String.Format("SELECT ResultsReturned FROM StoredFilters WHERE SecurityUserID = {0}", securityUserId);
string resultValue = DatabaseUtilities.QueryDatabase(selectCommand, ConfigurationManager.AppSettings["informconnectstring"].ToString(), "ResultsReturned");
ddResultNum.ClearSelection();
ddResultNum.SelectedIndex = ddResultNum.Items.FindByValue(resultValue);
}

and still no luck. I'd appreciate any help on figuring out why this drop down menu fails to update and represent / display the correct text for what is stored in the database.

-Cheers

Upvotes: 1

Views: 4698

Answers (2)

Jupaol
Jupaol

Reputation: 21365

Why don't you use the DropDownList.SelectedValue property???

For example:

ddResultNum.SelectedValue = resultValue;

Upvotes: 1

Shai Cohen
Shai Cohen

Reputation: 6249

You need to set the SelectedIndex property on the DDL itself. Like so (remember, the index is zero-based):

        switch (resultValue)
        {
            case "10":   
                ddResultNum.SelectedIndex = 0;
                break;
            case "20":
                ddResultNum.SelectedIndex = 1; 
                break;
            case "30":
                ddResultNum.SelectedIndex = 2;
                break;
            case "40":
                ddResultNum.SelectedIndex = 3;
                break;
            case "50":
                ddResultNum.SelectedIndex = 4;
                break;
            case "100":
                ddResultNum.SelectedIndex = 5;
                break;
        }

Upvotes: 0

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