Question

I have a Image Button declared as,

<div>
    <asp:ImageButton ID="btnDoWork" runat="server" ImageUrl="/_LAYOUTS/1033/IMAGES/row.png" ValidationGroup="Page" />
</div>
<div>
    <asp:RequiredFieldValidator runat="server" ID="reqName" ControlToValidate="txtEmail" ValidationGroup="Page" ErrorMessage="enter a email" />
    <asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" ValidationExpression="^([\w\.\-]+)@([\w\-]+)((\.(\w){2,3})+)$" ControlToValidate="txtEmail" ValidationGroup="Page" ErrorMessage="enter a email" />
</div>

within a update panel,

now in code behind I am doing something like this,

btnDoWork = (ImageButton)this.control.FindControl("btnDoWork"); //this code is in childcontrols method
btnDoWork.Click += new ImageClickEventHandler(btnDoWork_Click);

then

protected void btnDoWork_Click(object sender, ImageClickEventArgs e)
        {

//Process a bit of code and at end,

this.Page.Unload += new EventHandler(Page_Unload_MessageBox);

and then in button click event,

public static void Page_Unload_Page_Unload_MessageBox(object sender, EventArgs e)
        {
            System.Globalization.CultureInfo _culture = Thread.CurrentThread.CurrentUICulture;
            StringBuilder sb = new StringBuilder();
            sb.Append("<script language=\"javascript\">");
            sb.Append("$('body').append(\"<div id='M'><span id='text'>" +
               SPUtility.GetLocalizedString("$Resources:abc", "def", (uint)_culture.LCID) +
               "</span><br/><div id='BB' onclick='return BB();'><a href='' onclick='return BB();'>" +
               SPUtility.GetLocalizedString("$Resources:OK", "def", (uint)_culture.LCID) +
               "</a></div></div>\");");
            sb.Append("function BB() { $('#M').remove(); $('#E').remove(); return false; }");
            sb.Append("function dM(){   var browser = navigator.appName; if (browser == 'Netscape') { $('#M').css({ 'top': '5%' }, 500);    } }");
            sb.Append("</script>");

            // Write the JavaScript to the end of the response stream.
            HttpContext.Current.Response.Write(sb.ToString());

Now if I put email address I get error while when it tries to Response.Write I think, I wonder what alternative is there, e.g. can I use triggers in update panel or any other event or something..

here’s the error I am getting now,

Note: I changed all variable names so don’t get confused if something doesn’t match

Answer 1

The message is very clear, you can not add this command HttpContext.Current.Response.Write on update panel, and that because can not know how to handle it, because the update panel is return a struct that is used by the javascript to redraw some part of the page.

The solution is to add a literal control inside the UpdatePanel, in the place you wish to add the extra html code, and write that control the render as:

txtLiteralID.Text = sb.ToString();

How ever, here you have a diferent situation than the normal, you won to render and run a script.

The main problem is how to trigger the script to run. The only way is to use the UpdatePanel handler that is this standard code:

<script type="text/javascript"> 
   // if you use jQuery, you can load them when dom is read.
   $(document).ready(function () {
       var prm = Sys.WebForms.PageRequestManager.getInstance();    
       prm.add_initializeRequest(InitializeRequest);
       prm.add_endRequest(EndRequest);

    });        

    function InitializeRequest(sender, args) {
    }

    function EndRequest(sender, args) {
       // after update occur on UpdatePanel run the code.
       UnloadMsgBox();
    }
</script>

Now on the EndRequest you need to call your script, where it may all read exist in your code as:

function UnloadMsgBox()
{
    // render your code of the javascript.
    $('body').append(\"<div id='M'><span id='text'></span><br/><div id='BB' onclick='return BB();'><a href='' onclick='return BB();'></a></div></div>\");

    function BB() { $('#M').remove(); $('#E').remove(); return false; }"
    function dM(){   var browser = navigator.appName; if (browser == 'Netscape') { $('#M').css({ 'top': '5%' }, 500);    } }"
}

and not need to render it on UpdatePanel.

To summarize:

• On the update panel you can not use the Response.Write to render something but a literal control, that renders inside him.
• On the update panel you can not render javascript code and expect to run, to run a javascript code you need to use the EndRequest handler that comes with the UpdatePanel.