Error in selection change of item in DropdownList

Question

In ASP.NET project I have to load the content( TextBlock,Buttons etc) based on item selction

<asp:DropDownList ID="ddl_FieldType" CssClass="form-control" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddl_FieldType_SelectedIndexChanged">
    <asp:ListItem Text="Single Line Text" Value="0"></asp:ListItem>
    <asp:ListItem Text="Multiple Line Text" Value="5"></asp:ListItem>
    <asp:ListItem Text="Date Time" Value="2"></asp:ListItem>
    <asp:ListItem Text="Date Only" Value="4"></asp:ListItem>
    <asp:ListItem Text="Single Select" Value="1"></asp:ListItem>
    <asp:ListItem Text="Multiple Select" Value="6"></asp:ListItem>
    <asp:ListItem Text="Yes / No" Value="3"></asp:ListItem>
</asp:DropDownList>

I faced error while changing item selection related to postback or callback:

are you dynamically adding elements in the dropdown list on client side? — Akshey Bhat, Dec 30 '15 at 11:40
Possible duplicate of [Invalid postback or callback argument. Event validation is enabled using ''](http://stackoverflow.com/questions/228969/invalid-postback-or-callback-argument-event-validation-is-enabled-using-page) — Salah Akbari, Dec 30 '15 at 11:40
I have controlled display of content by setting the visibility=true or false of items based on selection in Dropdown list. But i faced error .. — jayanta, Dec 30 '15 at 11:46
@Frebin Francis i have only changed visibility in selection change of dropdown list — jayanta, Dec 30 '15 at 12:08
@jayanta can you please retry with set enableEventValidation property to false in your page ? — Frebin Francis, Dec 30 '15 at 12:10
@Frebin Francis enableEventValidation property to false works fine .But is is it good to do so ?? — jayanta, Dec 30 '15 at 12:30
if we want to modify the server side elements using client side scripts we need to do this. — Frebin Francis, Dec 30 '15 at 12:32
@jayanta or you can use asp.net ajax controls and set the visibility via ajax update panels. — Frebin Francis, Dec 30 '15 at 12:34

apexlol · Answer 1 · 2015-12-30T13:44:47.713

I would probably try to achieve this with javascript.

Something like this should work:

<asp:DropDownList ID="ddl_FieldType" CssClass="form-control" runat="server" Onchange=findselected()>
<asp:ListItem Text="Single Line Text" Value="0"></asp:ListItem>
<asp:ListItem Text="Multiple Line Text" Value="5"></asp:ListItem>
<asp:ListItem Text="Date Time" Value="2"></asp:ListItem>
<asp:ListItem Text="Date Only" Value="4"></asp:ListItem>
<asp:ListItem Text="Single Select" Value="1"></asp:ListItem>
<asp:ListItem Text="Multiple Select" Value="6"></asp:ListItem>
<asp:ListItem Text="Yes / No" Value="3"></asp:ListItem>

<script type="text/javascript">
            function findselected() {
                var selMenu =    document.getElementById('<%=DropDownList1.ClientID%>');
                var someField = document.getElementById('<%=TB1.ClientID%>');
                var anotherField = document.getElementById('label1');
                var btnField= document.getElementById('<%=ExportBtn.ClientID%>');
                if (selMenu.value == '2' || selMenu.value =='3') {
                    someField.style.display = "none";
                    anotherField.style.display = "none";
                    btnField.style.display = "none";
                }
                else {
                    someField.style.display = "";
                    anotherField.style.display = "";
                    btnField.style.display = "";
                }
            }
 </script>

Hope this helps, Apex

Error in selection change of item in DropdownList

1 Answers1