Troubleshooting Microsoft.Ajax Beta 1: Loss of ScriptManagerRegisteredScriptsBlocks after ModalPopup
In my previous
blogs/forum
entry, I outlined a workaround for displaying a modal form over top of a
gridview. Now, I am troubleshooting some of the behaviors.
The problem
with setting the UpdatePanel (that wraps the Gridview & associated controls)
to mode="Always" is that (which btw is not a requirement to make the work around
work for FireFox) it does a postback of the contents of the UpdatePanel on each
request for the UpdatePanel. In other words no asynchronous processing actually
takes place for that actual UpdatePanel.
So, my goal was to troubleshoot and see if there is a
cleaner work around at minimum. I had to close all of the IE sessions I had due
to memory issues and once done with that task - I began to notice actual script
errors occuring. No idea why I was not getting them before, but now each time I
move over a row in a gridview AFTER invoking the modal popup and closing it,
suddenly I get a ton of null reference errors. Additionally when invoking the
Modal I was getting a nasty 'screen flicker' - which is not very pleasant to
work with prior to display of the modal.
Interestingly enough - and again - when the page loads the
first time - there are NO SCRIPT errors. Gridview select options work for
sorting and such and provides the expected UI experience when ajax enabled.
We can back up a sec. The gridview
uses a java script routine to highlight rows on mouseover and also changes the
background row color of a selected item. Typical UI enhancement for the
gridview as it makes it more user friendly especially when working with alot of
data.
The code is relatively
simple. On the pre-render phase we register the script into the Script Manager
as per the new reuirements for Beta 1.
protected override void OnPreRender(EventArgs e)
{
if
(!Page.IsPostBack)
{
string script = @"
var _oldColor;
function
SetNewColor(source)
{ _oldColor =
source.style.backgroundColor;
source.style.backgroundColor = '#00ff00';}
function SetOldColor(source)
{ source.style.backgroundColor = _oldColor; }";
ScriptManager.RegisterClientScriptBlock(this, typeof(Page), "ToggleScript",
script, true);
} |
Then in the Gridview's DataBound
event we wire up some row behaviors:
protected virtual void
GridView_RowDataBound(Object s, GridViewRowEventArgs e)
{
if
(e.Row.RowType == DataControlRowType.DataRow )
{
//Note:
Here is where we change the button submit so that
//our IPostBackHandler can properly handle
AJAX requests.
int editID =
(int)DataBinder.Eval(e.Row.DataItem, "id");
e.Row.Attributes.Add("onMouseOver",
"SetNewColor(this);");
e.Row.Attributes.Add("onMouseOut", "SetOldColor(this);");
e.Row.Attributes.Add("onDblClick",
Page.ClientScript.GetPostBackEventReference(this,
e.Row.RowIndex.ToString()));
e.Row.Attributes.Add("onKeyDown", "if( event.keyCode == 13 ) " +
Page.ClientScript.GetPostBackEventReference(this, "KEYDOWN" + "$" +
e.Row.DataItemIndex.ToString())); |
Typical method of performing this
task. Note that I am only inserting the
ScriptManager.RegisterClientScriptBlock(..something) if
Page.IsPostBack is
true. The
assumption here is that if we are running in "Conditional Mode" (and I would
assume should still be in "Always" mode... then everything is async and the
Script's are still on the client.
However, somehow the scripts are not being kept on the
client - and thus when the modal closes, the script is lost (probably on the
initialization of the ModalPopup), and script errors will abound when moving the
mouse over the Gridview.
The
only solution is not to check for the postback and always send the script
downstream. Which really makes no sense since the client side is supposed to
already have it. I can understand maybe the requirement for it always being
sent if the UpdatePanel mode is "Always" although not really. Ajax is supposed
to only UpdatePanel not the entire page when a asynch request is made. So, if
the ScriptManager has the script registered it should remain so on the client
unless the client does a "refresh" from the browser or navigates again to the
page (say a menu for the option exists on the page) or any other words the page
request is not a postback For whatever reason, the ModalPopup wipes out the
script and maybe the 'flickering of the page' what appears to be a full postback
but we know that can be true because the !Page.IsPostBack is false and if it was
a full postback - then the script would be sent downstream.
Is there perhaps some guideance on
this or is this possibly a bug as well....