my dropdownlist generates an error after postback : The Official Microsoft ASP.NET Forums

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my dropdownlist generates an error after postback

Mar 31, 2012 11:31 PM|LINK

Hi all

I have two Drop down lists : (ddlUserID and ddlUserID0)

ddlUserID is filled using sqldatasource during page load.

ddlUserID0 is filled based on the selection from ddlUserID using the following javascript code

function AppendUsers()
        {
            var opt = document.createElement("Option");
            var i =document.getElementById("ddlUserID").selectedIndex;
            
            opt.text = document.getElementById("ddlUserID").options[i].text;
            opt.value = i;
            
                document.getElementById("ddlUserID0").options.add(opt);
        }

The above code works fine BUT when I try to save or if any postback happens, I get a long error message as follows :

Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.

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Re: my dropdownlist generates an error after postback

Apr 01, 2012 01:10 AM|LINK

Look at the code in the top of your aspx page and change EnableEventValidation="true" to EnableEventValidation="false".

If you dont see that code in your aspx page then look for it in your webconfig file and change it there

Please "Mark as Answer" if this resolved your issue

Marked as answer by Allen Li - MSFT on Apr 09, 2012 01:26 AM

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roopeshreddy

All-Star

20143 Points

3327 Posts

Re: my dropdownlist generates an error after postback

Apr 01, 2012 02:03 AM|LINK

Hi,

You can try registering you event!

Page.ClientScript.RegisterForEventValidation(myDropDown.ClientID);

http://blogs.msdn.com/b/amitsh/archive/2007/07/31/why-i-get-invalid-postback-or-callback-argument-errors.aspx

Hope it helps u...

Thanks & Regards
Roopesh Reddy C
Roopesh's Space

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human2x

Member

118 Points

81 Posts

Re: my dropdownlist generates an error after postback

Apr 01, 2012 06:33 AM|LINK

Dear Bakra

Your answer stoped the compilation error but the filled drop down list (ddlUserID0) was reset and became blank.

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bakra

Member

342 Points

59 Posts

Re: my dropdownlist generates an error after postback

Apr 01, 2012 11:55 AM|LINK

Hi haman2x

Can you ensure that you change the ClientIDMode of the the drop down list that is bound to the sql datasource (ddlUserID) to "Static" e.g.

<asp:DropDownList ID="ddlUserID" runat="server"
DataSourceID="sqlDatasource" DataTextField="textField"
DataValueField="valueField" ClientIDMode="Static">
</asp:DropDownList>

Please "Mark as Answer" if this resolved your issue

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human2x

Member

118 Points

81 Posts

Re: my dropdownlist generates an error after postback

Apr 01, 2012 01:17 PM|LINK

I tried that but it still gets reset and becomes blank

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bakra

Member

342 Points

59 Posts

Re: my dropdownlist generates an error after postback

Apr 01, 2012 02:29 PM|LINK

Can you ensure that you change the ClientIDMode of the the other drop down list as well (ddlUserID0) to "Static"

If changing both drop down lists to static does not work can you post your full code as this would be more helpful in diagnosing the problem

Pleas "Mark as Answer" if this resolved your issue

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human2x

Member

118 Points

81 Posts

Re: my dropdownlist generates an error after postback

Apr 01, 2012 08:48 PM|LINK

thanks bakra for your care

the full page code is below

<%@ Page Language="VB"  AutoEventWireup="false" CodeFile="CreateTask.aspx.vb" EnableEventValidation="false" Inherits="CreateTask" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
<link href="Styles/NewTask.css" rel="stylesheet" type="text/css" />
</head>
<body style="direction: rtl">
    <form id="form1" runat="server">
    <div id="wrapper">
    <div id="header">
    </div>
    <div id="main">
      <table width="100%" border="0" id="NewTask">
        <tr>
          <th width="18%" align="left" scope="row">
              TASK NAME</th>
          <td colspan="3" align="right">
            <asp:TextBox ID="txtTaskName" runat="server" Height="1.5em" Width="95%"></asp:TextBox>
            </td>
        </tr>
        <tr>
          <th align="left" scope="row" >
              TASK DATE</th>
          <td colspan="3" align="right" style="direction: ltr; margin-left: 80px;">
            <asp:TextBox ID="txtActionDate" runat="server" Height="1.5em" Width="30%"></asp:TextBox>
            </td>
        </tr>
        <tr>
          <th align="left" scope="row" >DURATION</th>
          <td colspan="3" align="right">
              <asp:TextBox ID="txtDuration"
                  runat="server" Height="1.5em" Width="10%"></asp:TextBox>
            &nbsp;&nbsp;
            <asp:DropDownList ID="ddlTimeUnit" runat="server" Height="1.5em">
                  <asp:ListItem Value="1">MIN</asp:ListItem>
                  <asp:ListItem Value="60">HOUR</asp:ListItem>
                  <asp:ListItem Value="1440">DAY</asp:ListItem>
                  <asp:ListItem Value="43200">MONTH</asp:ListItem>
              </asp:DropDownList>
            </td>
        </tr>
        <tr>
          <th align="left" scope="row" >TASK TO</th>
          <td width="35%" align="right" >
              <asp:DropDownList ID="ddlUserID" runat="server" AppendDataBoundItems="True" Height="1.5em" Width="80%"
                  DataSourceID="sdsUsers" DataTextField="UserName" DataValueField="UserID" onchange="AppendUsers();"
                  ClientIDMode="Static"  >
              </asp:DropDownList>
            </td>
          <td width="26%" align="right" >
              <asp:DropDownList ID="ddlUserID0" runat="server" Height="1.5em" Width="181px" ClientIDMode="Static" >
              </asp:DropDownList >
            </td>
          <td width="21%" align="right" >
              <asp:Button ID="Button1" runat="server" Text="DELETE"
              onclientclick="return RemoveUser();" Width="49px" />
          </td>
        </tr>
        <tr>
          <th align="left" scope="row" >APPOINTMENT</th>
          <td colspan="3" align="right">
            <asp:TextBox ID="txtActionDate0" runat="server" Height="1.5em" Width="30%"></asp:TextBox>
            </td>
        </tr>
        <tr>
          <th align="left" scope="row" >TASK DETAILS</th>
          <td colspan="3" align="right">
            <asp:TextBox ID="txtDetails" runat="server" Height="7em" TextMode="MultiLine"
                  Width="95%"></asp:TextBox>
            </td>
        </tr>
        <tr>
          <th align="left" scope="row" >TASK NOTES</th>
          <td colspan="3" align="right">
            <asp:TextBox ID="txtNotes" runat="server" Height="3em" TextMode="MultiLine"
                  Width="95%"></asp:TextBox>
            </td>
        </tr>
        <tr>
          <th align="left" scope="row" >&nbsp;</th>
          <td colspan="3" align="right">
              <asp:Button ID="cmdCreate" runat="server" Font-Size="Medium" Text="CREATE" Width="100px"
               />
              <asp:Button ID="Button2" runat="server" Text="Button" />
            </td>
        </tr>
      </table>
    </div>
    </div>
    <asp:SqlDataSource ID="sdsUsers" runat="server"
        ConnectionString="<%$ ConnectionStrings:tasksConnectionString %>"
        ProviderName="<%$ ConnectionStrings:tasksConnectionString.ProviderName %>"
        SelectCommand="SELECT UserID, UserName FROM users ORDER BY UserName">
    </asp:SqlDataSource>
    </form>

    <script type="text/JavaScript">
        function AppendUsers() {
            var opt = document.createElement("Option");
            var i = document.getElementById("ddlUserID").selectedIndex;
            opt.text = document.getElementById("ddlUserID").options[i].text;
            opt.value = i;
            opt.sno = document.getElementById("ddlUserID0").options.length + 1;
            //            var userID = document.getElementById("ddlUserID").value;
            //          alert (userID);
            //            document.getElementById("ddlUserID0").options.add(opt);
            //alert(document.getElementById("ddlUserID0").options.value);
            //alert(opt.value);
            //alert(opt.sno);

            x = document.getElementById("ddlUserID0");
            alert(x.length);
            if (x.length == 0) {
                document.getElementById("ddlUserID0").options.add(opt);
            }
            else {
                var flag = 0;
                for (j = 1; j <= x.length; j++) {
                    if (i == x.options[j - 1].value) {
                        flag = 1; //the name is already available
                        break;
                    }
                }
                if (flag == 0) { // if the name does not exist on the list
                    document.getElementById("ddlUserID0").options.add(opt);
                }
            }
        }

        function RemoveUser() {
            var x = document.getElementById("ddlUserID0")
            x.remove(x.selectedIndex);
            return false;
        }
    </script>
</body>
</html>

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bakra

Member

342 Points

59 Posts

Re: my dropdownlist generates an error after postback

Apr 01, 2012 11:26 PM|LINK

Add the following "onload" event to body tag in your html

<body onload="AppendUsers()"> //will call the function every time the page loads

Also add AutoPostBack="True" to your "ddlUserID" drop down list

          <asp:DropDownList ID="ddlUserID" runat="server" AppendDataBoundItems="True" Height="1.5em" Width="80%"

                  DataSourceID="sdsUsers" DataTextField="UserName" DataValueField="UserID" onchange="AppendUsers();"

                  ClientIDMode="Static" AutoPostBack="True">
              </asp:DropDownList>

Please "Mark as Answer" if this helped you

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DotNetRaven

Member

236 Points

52 Posts

Re: my dropdownlist generates an error after postback

Apr 02, 2012 05:50 AM|LINK

Use AJAX Update Panel For both The DropDownList's

Please remember to click " Mark As Answer " on the post that helps you. This can be beneficial to other community members reading the thread.
Good Luck

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11 replies

human2x

my dropdownlist generates an error after postback

bakra

Re: my dropdownlist generates an error after postback

roopeshreddy

Re: my dropdownlist generates an error after postback

human2x

Re: my dropdownlist generates an error after postback

bakra

Re: my dropdownlist generates an error after postback

human2x

Re: my dropdownlist generates an error after postback

bakra

Re: my dropdownlist generates an error after postback

human2x

Re: my dropdownlist generates an error after postback

bakra

Re: my dropdownlist generates an error after postback

DotNetRaven

Re: my dropdownlist generates an error after postback

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