PageMethod Static Ajax WebService and User Controls

I have a page HostPage.aspx, which is a generic hostpage that will dynamically load Web User Controls at runtime, according to the needs of various other users. Those other Web User Controls will be created by the other users, such that they can put anything they like in that Web User Control, and it will be dynamically populated and put in the HostPage.aspx. They will always use HostPage.aspx, they cannot edit it. This is working as-is, and everything is great.

Now, some users want to put AJAX functionality in their User Controls, such that the HostPage.aspx will contain their User Control, the User Control will contain an UpdatePanel, a ScriptManager, etc.

To enable page methods, we have to set the EnablePageMethods="true" on the scriptmanager, and have to declare a static method *somewhere*. The requirements are such that we cannot be declaring these static methods in the HostPage.aspx, because it cannot know what the controls, and therefore static methods, are until runtime. On the other hand, if we declare these static methods in the User Control, it's not defined in the HostPage, and AJAX PageMethod callbacks fail ("Method myMethod is not defined"), because the page doesn't know of it's existence.

1. Has anyone tried to do something similar to this, namely having AJAX controls in a User Control, which is hosted in a page, yet also needs to use the Page Methods, yet cannot declare them in the page (I know, that's pretty specific).

2. Any ideas on how this might be accomplished?

I'm thinking of using Reflection or DynamicMethod (http://msdn2.microsoft.com/en-us/library/system.reflection.emit.dynamicmethod.aspx) to make this happen, such that at runtime, the page will examine its child controls for any static methods with the ScriptService attribute, and then dynamically create a static method on itself with the same name, calling the child, but that is rather involved and I fear the performance risk of this (if this whole idea is even possible). Plus, the generated method wouldn't exist until after the controls exist, and I'm not sure where that falls in relation to the timing of the AJAX extensions (looking for the MethodName). It might be (probable) that the handler is looking for the method even before the controls are initialized, in which case that idea won't fly.

You can't do that... as described here (http://www.singingeels.com/Articles/Using_Page_Methods_in_ASPNET_AJAX.aspx) Page Methods are only on pages :)

But you can get what you want if you make your user control register a "web service" as in this article:http://www.singingeels.com/Articles/Consuming_Web_Services_With_ASPNET_AJAX.aspx

If your users aren't able to add webserivces (I really don't know the situation your building)... then they can register a regular old "AsyncPostBack" and wire it up themselves (sorry, no article on that yet).

Right, I understand completely the concept of PageMethods, that they are on pages, etc. That's why this is a bit of a tricky spot.

I guess what I'm looking for is whether anyone has come up with anything clever to get around this situation (PageMethods from a Usercontrol). The usersare free to create and consume their own webservices, if they like, but if possible, I would like to give them this functionality for this situation.

OK, I believe it's Page.ClientScript.RegisterAsyncPostBack or maybe ScriptManager.RegisterAsycnPostBack ( I can't remember )... either way, it'll post back to the page... and ultimately the user control, and fire an event (on the user control).

That'll work just like the page methods... (a little better actually for what you're doing)

Paging in GridView gets Object Expected Error

I have a grid in an update panel that gets databound at runtime (to index server results). I have implemented paging and it works without atlas. As soon as I place that grid in update panel, paging stops working. All I get is a javascript error saying "line 1 :Object Requiered".

I have tried debugging it but on paging, it doesn't event get to the server.

thanks

Hi Biren,

Have you tried this with the April CTP of Atlas that was released earlier this week?

If it's still a problem, can you please provide some more details on your scenario so that we can investigate?

Thanks,

Eilon

I have done it and it works for me. Object required is a pretty generic error just as the "Object reference not set to an..." in .Net. It could be because of wrong syntax in javascript or html that you might have on the page.

If you don't mind pasting the code on the forum please do so we can look at it.

Just tried it and same error.

here is the code:

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

<!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 id="Head1" runat="server">
<title>Search</title>
<link href="http://links.10026.com/?link=Style.css" rel="stylesheet" type="text/css" />
</head>
<body>
<atlas:ScriptManager EnablePartialRendering="true" ID="atlas1" runat="server" EnableViewState="true" />
<form id="frm1" runat="server">

<atlas:UpdateProgress ID="up11" runat="server" >
<ProgressTemplate >
<table>
<tr>
<th style="color:red">Please wait while your serach results are calculated...</th>
</tr>
<tr>
<td>
<img src="http://pics.10026.com/?src=images/spinner.gif" /></td>
</tr>
</table>

</ProgressTemplate>
</atlas:UpdateProgress>
<atlas:UpdatePanel ID="up1" Mode="conditional" runat="server" >
<ContentTemplate >



<table>
<tr>
<th>A word or phrase in the file: </th><td><asp:TextBox ID="txtsearch" runat="server" /></td>
</tr>
<tr>
<th>All or part of filename: </th><td><asp:TextBox ID="txtfilename" runat="server" /></td>
</tr>
<tr>
<th>When was it modified?:</th>
<td>
<asp:DropDownList ID="lstDuration" runat="server">
<asp:ListItem Text="Don't remember" Value="0" />
<asp:ListItem Text="Within the last week" Value="7" />
<asp:ListItem Text="Past Month" Value="30" />
<asp:ListItem Text="Within the past year" Value="365" />
</asp:DropDownList>
</td>
</tr>
<tr>
<td colspan="2"><asp:Button ID="btnSubmit" runat="server" Text="Search" /></td>
</tr>
</table>

<asp:GridView ID="grdResults" runat="server" CellPadding="4" ForeColor="#333333"
GridLines="None" AllowSorting="True" AllowPaging="True" PageSize="2" AutoGenerateColumns="False">
<Columns>
<asp:TemplateField HeaderText="Document Information">
<ItemTemplate>
<p>
<a href="http://links.10026.com/?link=<%# DataBinder.Eval(Container, "DataItem.path")%>">
<%# DataBinder.Eval(Container, "DataItem.Path")%>
</a>
<br />
<i>Last modified:
<%# DataBinder.Eval(Container, "DataItem.Write")%>
</i>
<br />
</p>
</ItemTemplate>
</asp:TemplateField>
</Columns>
<FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
<RowStyle BackColor="#F7F6F3" ForeColor="#333333" />
<EditRowStyle BackColor="#999999" />
<SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
<PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
<HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
<AlternatingRowStyle BackColor="White" ForeColor="#284775" />
</asp:GridView>

</ContentTemplate>

</atlas:UpdatePanel>
</form>
</body>
</html>

Code behind:

Partial Class Index
Inherits System.Web.UI.Page

Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSubmit.Click

' Bind DataGrid to the DataSet. DataGrid is the ID for the
' DataGrid control in the HTML section.
Dim source As New DataView(createDS.Tables(0))
grdResults.DataSource = source
grdResults.DataBind()

End Sub
Private Function createDS() As DataSet
Dim cnnOledb As New OleDb.OleDbConnection
Dim strQuery As String

Dim critstr As String = "(contains(filename,'.doc OR .xls OR .ppt OR .asp OR .aspx OR .txt'))"

If txtsearch.Text.Length <> 0 Then
critstr += " AND (contains(contents,'" + condition(txtsearch.Text) + "'))"
End If

strQuery = "Select DocTitle,Filename,VPath,Rank,Characterization,Write,path from SCOPE() where " + critstr + " order by write desc"

Dim connString As String = "Provider=MSIDXS;Data Source='o drive'"

Dim cn As New System.Data.OleDb.OleDbConnection(connString)
Dim cmd As New System.Data.OleDb.OleDbDataAdapter(strQuery, cn)
Dim objDS As New DataSet

cmd.Fill(objDS)

Return objDS
End Function

Function condition(ByVal srchstr As String) As String
Dim arr As String() = srchstr.Split(" ")
For i As Integer = 0 To arr.Length - 1
Dim str1 As String = arr(i)
If str1 <> "AND" And str1 <> "OR" And str1 <> "NOT" Then
arr(i) = "\" + str1 + "\"
End If
Next
Return String.Join(" AND ", arr)
End Function

Sub grdResults_PageIndexChanging(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewPageEventArgs) Handles grdResults.PageIndexChanging
grdResults.PageIndex = e.NewPageIndex
Dim source As New DataView(createDS.Tables(0))
grdResults.DataSource = source
grdResults.DataBind()

End Sub
End Class

Hi again,

I tried this out and I'm getting the same error. This turns out to be a known bug in the April CTP of Atlas. To work around it, add this code to your Page's Load event handler:

Page.ClientScript.GetPostBackEventReference(this, String.Empty);

Thanks,

Eilon

that works. Thank you. btw ATLAS ROCKS!!

Appears to be an issue in the June CTP too... and if it wasn't for this post, I'd still have the issue.

Thanks guys

Correct, this was not fixed in the June CTP. For now the one line workaround should still be sufficient.

Thanks,

Eilon

In the case of nested UserControls, does this workaround apply? If so, where should the workaround go?

I have a page which contains a UserControl, which in turn contains another UserControl, which contains a GridView wrapped in an UpdatePanel. I tried adding this line to the page's Page_Load and the UserControl's Page_Load, but I get the same generic error:

Line: 10846
Char: 17
Error: Object required
FYI, the offending line appears to be the second one pasted below:

function destroyTree(element, markupContext) {

if (element.nodeType == 1) {

Any ideas?

slp004, can you please give more details as to what you're trying to do? It sounds like other people on this thread have this scenario working so I'm curious what's going on here.

Thanks,
Eilon

I was never able to figure out exactly what the problem was, but by breaking the page up into a number of smaller pages sharing a single master page it started working again. There were just way too many UserControls inside GridView inside FormView inside UserControls inside View areas inside show/hide panels... you get the idea.

I have exactly the same problem - in the same line

 function destroyTree(element, markupContext) {if (element.nodeType == 1) {

My page have three or four levels of nested user controls inside the update panel. The curious thing is the page with the same controls has worked before some change I did - now I am trying to figure it out.

Wow, I figured out the issue.

The error was caused because I have another updatepanel in this page - inside a user control, included in master page. The user control has Visible=false. This scenario causes the error. When I set the user control visibility to true, the error goes off.

The solution is setting the updatepanel (that is inside the user control) mode to Conditional. This solves the problem even if the user control is invisible.

HTH.

I had the same problem and I set all the update panels to conditional and it worked.