How to populate second dropdownlist without postback?

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I have many dropdownlists and textboxes in a single page. I have done validations on textboxes. Each dropdownlist populate another dropdownlist. The problem is, all existing validation messages are disappear when selectedindexchanged event fired. How to populate second dropdownlist without postback?

Posted 24-Feb-15 3:19am

Member 9018012

Updated 15-Mar-17 3:00am

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Manoj Sawant · Answer 1 · 2015-02-24T20:23:00

hi,
you can make use of Updatepanel in your page, this will not postback your page. Check this i have used it. The ControlID given in the <asp:AsyncPostBackTrigger> is the Control on whose indexchanging changes the values in the second dropdown. update panel is to be applied on the second dropdown where the values has to be reflected without postback. in the example below year dropdown gets filled as per the process selected.

ASP.NET

<asp:UpdatePanel ID="upSetSession" runat="server">
             <ContentTemplate>
         <asp:DropDownList ID="ddlyear" runat="server" AppendDataBoundItems="True" CssClass="textarea" ValidationGroup="validate">
             <asp:ListItem>Please Select</asp:ListItem>
         </asp:DropDownList>
                 <asp:CustomValidator ID="CustomValidator1" runat="server" ClientValidationFunction="validateyear" ControlToValidate="ddlyear" Display="Dynamic" ErrorMessage="*" ForeColor="#FF3300" ToolTip="*" ValidationGroup="validate">*</asp:CustomValidator>
         </ContentTemplate>
              <Triggers>
                <asp:AsyncPostBackTrigger ControlID="ddlprocess" 
                    EventName="SelectedIndexChanged" />
            </Triggers>
       </asp:UpdatePanel>

Peter Leow · Answer 2 · 2015-02-24T03:49:00

Solution 1

Refer: cascading dropdownlist without postback[^]

Posted 24-Feb-15 3:49am

Peter Leow

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Member 9018012 24-Feb-15 10:53am

I used ajax call updatepanel and triggers.

Samatha Reddy G · Answer 3 · 2015-02-24T21:49:00

Solution 3

Using ajax call and Web Method you can bind dropdown wiht out postback

Posted 24-Feb-15 21:49pm

Samatha Reddy G

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Member 9018012 25-Feb-15 4:05am

Thanks. I have 7 dropdownlists which populates another dropdownlist. Is there any way to reduce code?

Dev parmar · Answer 4 · 2015-02-24T22:07:00

set validation group on validation control and button and use update panel for asynchronously bind drop down on selected Chang Event of another drop down
use update panel like
first declare ScriptManager your page

ASP.NET

<asp:ScriptManager ID="ScriptManager1" runat="server">
   </asp:ScriptManager>

ASP.NET

<asp:dropdownlist id="ddl1" runat="server" enableviewstate="False" >
</asp:dropdownlist>   
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
   <ContentTemplate>
          <asp:dropdownlist id="ddl2" runat="server" enableviewstate="False">
          </asp:dropdownlist>                                     
   </ContentTemplate>
   <Triggers>
   <asp:AsyncPostBackTrigger ControlID="ddl1" EventName="SelectedIndexChanged" />
   </Triggers>
</asp:UpdatePanel>

How to populate second dropdownlist without postback?

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