Issue while clicking on ImageButton

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XML

<asp:GridView ID="GridImport" runat="server" AutoGenerateColumns="false" Width="99%" Height="50%"
                                   AllowPaging="true" GridLines="None" Style="padding: 15px; text-align: left; overflow: scroll;
                                   font-family: Arial; font-size: 11pt;" ShowHeaderWhenEmpty="true" PageSize="5"
                                   CssClass="Grid_LE" HeaderStyle-CssClass="Grid_Head" EmptyDataText = "No files Imported">
               <Columns>
                   <asp:BoundField DataField="Text" HeaderText="File Name" />
                   <asp:TemplateField>
                       <ItemTemplate>
                        <%--   <asp:LinkButton ID="lnkDownload" Text = "Download" CommandArgument = '<%# Eval("Value") %>' runat="server" OnClick = "DownloadFile" ></asp:LinkButton> --%>
                             <asp:ImageButton ID="lnkDownload" runat="server" CommandArgument='<%# Eval("Value") %>'  Style="width: 24px; height: 24px;" ImageUrl="~/Images/download.png" OnClick="DownloadFile" />   <%--CommandName="Upload"--%>
                       </ItemTemplate>
                   </asp:TemplateField>
                   <asp:TemplateField>
                       <ItemTemplate>
                           <%--<asp:LinkButton ID = "lnkDelete" Text = "Delete" CommandArgument = '<%# Eval("Value") %>' runat = "server" OnClick = "DeleteFile" /> --%>
                             <asp:ImageButton ID="lnkDelete" runat="server" CommandArgument='<%# Eval("Value") %>'  Style="width: 24px; height: 24px;" ImageUrl="~/Images/cancel.png" OnClick="DeleteFile" />
                       </ItemTemplate>
                   </asp:TemplateField>
               </Columns>
           </asp:GridView>

HERE is my DownloadFile function
--------------------------------------

C#

protected void DownloadFile(object sender, EventArgs e)
       {
           string filePath = (sender as ImageButton).CommandArgument;
           Response.ContentType = ContentType;
           Response.AppendHeader("Content-Disposition", "attachment; filename=" + Path.GetFileName(filePath));
           Response.WriteFile(filePath);
           Response.End();
       }

WHILE CLICKING ON DOWNLOAD BUTTON I AM GETTING THIS ERROR

XML

Server Error in '/' Application.

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.

HOW CAN I SOLVE THIS?

Posted 6-Nov-14 19:34pm

jithesh a

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3 solutions

Solution 1

This error may be thrown when you click on your command and the Page_load is being ran again. Bind data only the first time when your page load, like below

C#

if (!Page.IsPostBack)
{ 
   //bind data to  GridImport
}

hope this helps, there may be many other reasons for the same error, this is the common mistake I have pointed first.

Posted 6-Nov-14 19:42pm

DamithSL

Solution 3

Hi,

I guess Set Command Name and Handle row Command Event to process

your Grid View as

XML

<asp:GridView ID="GridImport" runat="server" onrowcommand="GridView1_RowCommand" >

Your Image Button as

<asp:ImageButton ID="lnkDownload" runat="server" CommandArgument='<%# Eval("Value") %>'  Style="width: 24px; height: 24px;" ImageUrl="~/Images/download.png" CommandName="DownloadFile" />

then Row Command Event

C#

protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
        {
            if (e.CommandName == "DownloadFile")
            {
                string filePath = (sender as ImageButton).CommandArgument;
                Response.ContentType = ContentType;
                Response.AppendHeader("Content-Disposition", "attachment; filename=" + Path.GetFileName(filePath));
                Response.WriteFile(filePath);
                Response.End();
            }
        }

Thanks

Siva Rm K

Posted 6-Nov-14 19:53pm

rmksiva

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Laiju k · Accepted Answer · 2014-11-06T19:44:00

Solution 2

VB

<%@ Page Title="" Language="C#" 
EnableEventValidation="false" %>

change EnableEventValidation="false" in page

Posted 6-Nov-14 19:44pm

Laiju k

Comments

jithesh a 7-Nov-14 2:14am

Thanks ;)