Nikhil Kothari's Weblog : UpdateControls 1.1: Bug Fixes and UpdateAction

I posted an initial version of my UpdateControls package - a set of ASP.NET AJAX server controls that build on the partial rendering model to extend the model beyond basic page updates. The package consisted of the UpdateHistory and the AnimatedUpdatePanel controls. Theres been quite a few downloads of it, and quite a few comments as well, including bug reports.

If this is the first time you're reading about this, check out my previous blog post on this first and then come back here to see whats changed. Various bugs that have been reported have been fixed including:

Support for installing to the GAC: The assembly is now signed, and you can add to the GAC if you like, or leave it in the bin directory of your Web application if you can't or don't want to.
Support for master page and user control scenarios: The UpdateHistory control now works in either of those scenarios. Remember you can still only have one UpdateHistory control on your page.
Support for bookmarking: Bookmarking was broken ... doh! The ability to bookmark and return to specific views of a page is a key scenario for the UpdateHistory control, and is now fixed.
Support for debug ASP.NET AJAX scripts: The UpdateHistory control is non-visual, however the framework expects there to be a matching element as it causes post-backs upon back/forward navigation, so I've made minor changes, so as to avoid the debug assert raised by the framework.

In addition to fixing the bugs, I've added a new control to the pack in v1.1 - UpdateAction. As the name might suggest, it enables you to perform a small selection of actions as part of a partial rendering or async postback. Specifically it currently allows you to show a message, set focus on a particular control, or scroll the page to a particular control. The usage is straightforward, and the download contains a sample. Here are the basics:

Step 1 is to add an instance of this control to your page.

<nStuff:UpdateAction runat="server" id="updateAction" />

Step 2 is to call APIs on this control from appropriate event handlers on the page. In the samples I have a DropDownList control, and demonstrate conditionally performing certain actions when a certain item is selected. To that end, you might have something like this:

private void DropDownList1_SelectedIndexChanged(object sender, EventArgs e) {
    if (DropDownList1.SelectedIndex == 2) {
        updateAction.ShowMessage("You selected the magic item");
        updateAction.SetFocus(someControl);
        updateAction.ScrollTo(someControl, ScrollOffset.Bottom);
    }
}

Thats basically it. Do you think these are useful actions? Any others that are interesting?

You can download the control package, sources and associated samples here for free. I have a couple more ideas in mind for a future iteration of this package, and suggestions are always welcome, in addition to continued feedback on the existing controls.

Posted on Friday, 4/13/2007 @ 4:14 PM | #ASP.NET

Comments

Nikhil Kothari

Posted on 4/13/2007 @ 9:48 PM

Daniel - UpdateAction doesn't cause a postback... thats not the use model. The idea is that you have some other control that causes a postback, eg. a button... and during that postback parts of the page get updated (by virtue of UpdatePanel controls). If in addition to updating parts of the page, your want to show a message, or perform some other action, then you can use UpdateAction to perform those actions when the page does get updated back on the client.

Steve - The snk file I used to sign the assembly is intentionally not part of the package. Generally most people will just use the built dll that is in the bin directory of the site. If you do want to rebuild the sources, you'll need your own key file, so its doesn't get mixed up with the assembly I build and hand out from my site.

Jerome

Posted on 4/18/2007 @ 2:14 AM

Hi all,
What is the best way to deploy those examples locally?

In VS2005, I created a new project : ASP.NET AJAX-Enabled Web Application.
I added Sample.master, Default.aspx, CrossFadeAnimation.aspx then the nStuff.UpdateControls dll in the References folder.
When I launch "Start debugging" (F5), the cross fade animation works fine.
But if I exit VS2005 and create a virtual directory to that project in IIS, I get the following error when accessing CrossFadeAnimation.aspx (in FF2 - Firebug) :

Sys.WebForms has no properties
nStuff_AnimatedUpdatePanel$initialize()ScriptResource.ax... (line 105)
Sys$Component$endUpdate()ScriptResource.ax... (line 2702)
Sys$Component$create(nStuff_AnimatedUpdatePanel(element), Object animation=Object, null, null, div#_ctl0_mainContent_mainUP_Container)ScriptResource.ax... (line 2856)
(no name)()CrossFadeAnimatio... (line 122)
_handler(Object _disposableObjects=[2] _components=Object, Object)ScriptResource.ax... (line 2503)
Sys$_Application$_doInitialize()ScriptResource.ax... (line 3792)
(no name)()ScriptResource.ax... (line 50)
[Break on this error] var prm = Sys.WebForms.PageRequestManager.getInstance();

Why do I have a different behavior ?
Something to do with UpdateControls.js apparently ?...
Thanks for your tips.

Dan

Posted on 4/22/2007 @ 1:02 PM

I use one or more radiobutton lists/dropdownlists and/or text fields to define the section criteria for a gridview with links to detail page in lots of places. I appreciate your efforts on making UpdatePanels viable.

Your latest code solves most of this problem, but one remains. Your example depends on the first entry in your dropdown being a label for the dropdown, not an actual selection so that your code doesn't update the history with the 0'th section index.

If my user changes the radiobutton/dropdown from the 1st entry to the 2nd and then back to the first, the gridview is return the the original version but a selection of a link in that grid followed by a back arrow, will show the 2nd version of the gridview not the first.

You can reproduce this on your samples, by selecting a technogy - seeing the result fill in - selecting the 'Select a technogy' - seeing the result clear - clicking the "created with Script#" - clicking the back button, then you will see the technology that you previously set and then cleared!

So I guess that when the user links from the gridview to a detail page, that detail page must now communicate back that all dropdown/radiobutton onselectionchanges until the after the next page render should be ignored.
Or can the page load capture the history state for when the OnNavigate is driven.

Am I confused or what? Thanks

Dan

Posted on 4/25/2007 @ 10:30 PM

I tried a few more combinations and now it all works (except those gridviews with paging). What works for me is to have no extra code in the radiobox/textbox/dropdown onwhateverchanged.
I have
using nStuff.UpdateControls;
using System.Text.RegularExpressions;
and a
updateHistory.AddEntry(
pName.Text
+ ":" + pTables.SelectedIndex.ToString()
+ ":" + pDonor.SelectedIndex.ToString()
+ ":" + pActive.SelectedIndex.ToString());
as the first statement of my OnPreRender and define
protected void OnUpdateHistoryNavigate(object sender, HistoryEventArgs e)
{
// Raised when the user navigates back/forward or
// loads a bookmark to a specific view.

// Use the history entry name to determine the
// selected index and update the page.
int selected1Index = 0;
int selected2Index = 0;
int selected3Index = 0;
if (String.IsNullOrEmpty(e.EntryName) == false)
{
Regex rColon = new Regex(":");
string[] sArgs = rColon.Split(e.EntryName);
selected1Index = Int32.Parse(sArgs[1]);
selected2Index = Int32.Parse(sArgs[2]);
selected3Index = Int32.Parse(sArgs[3]);
pName.Text = sArgs[0];
}
pTables.SelectedIndex = selected1Index;
pDonor.SelectedIndex = selected2Index;
pActive.SelectedIndex = selected3Index;

PersonsView.DataBind();
DisplayUpdatePanel.Update();
SelectorUpdatePanel.Update();
}

and in the aspx
<%@ Register Assembly="nStuff.UpdateControls" Namespace="nStuff.UpdateControls"
TagPrefix="nStuff" %>
<%@ MasterType VirtualPath="~/Master1.master" %>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit"
TagPrefix="ajaxToolkit" %>
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1"
runat="Server">
<asp:ScriptManager runat="server">
</asp:ScriptManager>
<nStuff:UpdateHistory runat="server" ID="updateHistory"
OnNavigate="OnUpdateHistoryNavigate" />
<nStuff:UpdateAction runat="server" ID="updateAction" />
etc

works like a charm!

Sean

Posted on 5/24/2007 @ 2:54 PM

If a user hits the browser's refresh button, I have figured out how to make my control retain the information they contained by storing the viewstate in a Session variable, but all previous history entries made by your control are deleted - which means the user cannot navigate back anymore. The other problem is that I could reset the user back to the initial page, but that intial page is now marked with the anchor (UpdateHistory entry) of whatever page was refreshed and that just makes the initial page unreachable from any future pressing of the back button. Fun stuff.

For me, the ideal solution is not losing the back button history on a refresh. Second best solution is making your UpdateHistory control remove the anchor from the back button URL entry if the control knows this is not a PostBack.

Am I missing anything some other solution here?

RobM

Posted on 11/9/2007 @ 3:38 PM

Great set of web controls Nikhil!

I wonder if you could help with the following scenario? I've done some research but honestly my lack of understanding ASP.NET I feel is keeping me from finding an answer. I've been coding in windows too long apparently!

Assume you have a page like you History.aspx page. You can select items from the drop-down all day long, watch the back button become enabled and the history being written in the url. You can then select back / forward browser buttons and OnNavigate event fires and all works as expected.

But, if you had a button on your history.aspx page which redirected to another page, (call it page X) and then you use the back button from page X to return to History.aspx the asp.net page lifecycle model fires twice. Once for the normal page load and then a second time when the async operation occurs, firing the OnNavigate event. (as expected).

This scenario is causing me problems because I have a page of summary rows. The user can select a button on a summary row to view the details page. The user can then use the back button to return to the summary page. The summary page then loads twice. The first time it fires it loads all the data and resets to the first summary page (users can filter the data on the summary page, which is why i'm using the UpdateHistory control to track the filter set). The second time the page life cycle repeats itself is for the OnNavigate event. This forces a load of the summary page albeit to the right set of filtered data. This makes my page look funky as it loads a set of data with no filters, then it reloads the data with the filters set. (The filters are comb-boxes btw, not that the filter types matter).

This was really my first ASP.NET application and I decided AJAX was the way to implement the summary data view so the user could filter and navigate the dataset without full page updates. Maybe I should just use a query string and not worry about page refreshes. This would take care of my scenario.

Thanks again for the controls.

UpdateControls 1.1: Bug Fixes and UpdateAction

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