PreInit event in usercontrol

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Marcelo Cabrera - 22 Dec 2005 20:06 GMT

Hi,

I have a user control that in turn creates a bunch of webcontrols
dynamically and handles the events these webcontrols raise. It used to work
fine on ASP .Net 1.1 but when compiled on 2.0 it does not. The problem is
that the webcontrols get created on the OnLoad event of the usercontrol and
the event handlers are assigned at the same time. I have to click twice on
the controls for the events to be raised, the first time nothing happens,
the second time the event handler fires up.

Reading the msdn info it says that for pages, the dynamically created
webcontrols should be created in the PreInit event of the page, but
usercontrols do not have that event, what is the life-cycle for
usercontrols.

Also the usercontrol is dynamically loaded into the page at the Load event.

Thanks,
Marcelo Cabrera.

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Steven Cheng[MSFT] - 23 Dec 2005 03:50 GMT

Hi Marcelo,

Welcome to ASPNET newsgroup.
Regarding on the dynamic creating webcontrols in UserControl or in asp.net
2.0 web page problem, here are some of my understanding and suggestion:

1. For dynamic webcontrols, it's ok to create them in Page's Load or Init
event (Init is the prefered one), this is also the recommendation in
asp.net 1.1:

#HOW TO: Dynamically Create Controls in ASP.NET by Using Visual C# .NET
http://support.microsoft.com/kb/317794/en-us

2. For asp.net 2.0, the reason why we recommend that put dynamic controls
creation code in PreInit event is the ASP.NET 2.0's Theme/Skin service is
applying skin to controls before Init event, so we need to add dynamic
controls in page's controls structure in PreInit so as to automatically
utilize the page's Theme setting.... But if we create them in Init or
Load, we can also manually apply page theme for control through
Control.ApplyStyleSheetSkin() method , e.g:

===================
TextBox txt = new TextBox();
txt.ID = "txtUC";
txt.AutoPostBack = true;
txt.TextChanged += new EventHandler(txt_TextChanged);

phControls.Controls.Add(txt);
txt.ApplyStyleSheetSkin(Page);
====================

For your scenario, I think the event handler problem may caused by how your
Usercontrol (the container) is created and added into page's collection. Is
the usercontrol always created and added into page in page's Init or Load
event ?

If possible, would you provide a simplfied page and the usercontrol so that
we can have a look into the detailed code logic?

Thanks & Merry Christmas!

Steven Cheng
Microsoft Online Support

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--------------------

| From: "Marcelo Cabrera" <marcelocabrera@noemail.noemail>
| Subject: PreInit event in usercontrol
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microsoft.public.dotnet.framework.aspnet:366633

| X-Tomcat-NG: microsoft.public.dotnet.framework.aspnet
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| Thanks,
| Marcelo Cabrera.

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Steven Cheng[MSFT] - 29 Dec 2005 10:19 GMT

Hi Marcelo,

How are you doing on this issue or does my last reply helps you a little?
If there're anything else we can help, please feel free to post here.

Regards,

Steven Cheng
Microsoft Online Support

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Marcelo Cabrera - 01 Jan 2006 20:11 GMT

Hi Steven,

I was on vacation last week, thanks for the reply.
I don't think the problem could be solved without a way to add the handlers
for the controls created dynamically. In other words, what's the equivalent
of preinit for a usercontrol?

The thing is, I have an .ASCX page with a placeholder which in turn gets
populated with a few usercontrols in the codebehind, then, those usercontrols
have their own events and eventhandlers which in turn may load some other
usercontrols during the pageload event of the usercontrols. When that happens
the events in the second tier usercontrols don't fire until the second time
the user clicks. It all used to work well on 1.1 but with 2.0 something
broke, I tried moving the controls creation and event wiring to the pageinit
as stated in the documentation (for ascx) but I can't find info about the
page life cycle for usercontrols.

The usercontrols are always created and added to the page(s) during the load
and/or preinit events.

Thanks in advance,
Marcelo Cabrera.

> Hi Marcelo,
>
[quoted text clipped - 125 lines]
> | | Thanks,
> | | Marcelo Cabrera.

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Steven Cheng[MSFT] - 03 Jan 2006 10:29 GMT

Thanks for your response Marcelo,

So I can currently get that you dynamically load some container
userControls in the aspx page. Then, in those container usercontrol's
certain postback events, you create and load some other sub usercontrols,
and add event handlers for those sub usercontrols? What's the event, your
custom defined events or buildin events?

Anyway, Usercontrols dosn't have PreInit event (different from Custom
Server control...), we have only Init , Load event for usercontrol where we
should put the dynamic child controls creation code....

Thanks,

Steven Cheng
Microsoft Online Support

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| Subject: RE: PreInit event in usercontrol
| Date: Sun, 1 Jan 2006 12:11:02 -0800
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Marcelo Cabrera - 03 Jan 2006 15:43 GMT

Steven,

Yes, you got it right. the events are builtin events, when I need to
bubble-up events to the parent usercontrol (for example to remove the child
control) that works fine, simple built-in events like button onclick are the
events that need to be triggered twice before getting processed.

Thanks,
Marcelo Cabrera.

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Steven Cheng[MSFT] - 04 Jan 2006 10:10 GMT

Thanks Marcelo,

Would you provide me a simplified page and usercontrol with some buildin
controls(button or textboxes) that are dynamicall loaded and bind event
handlers so that I can perform some test on them?

Regards,

Steven Cheng
Microsoft Online Support

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| Subject: RE: PreInit event in usercontrol
| Date: Tue, 3 Jan 2006 07:43:03 -0800
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| > | > | | Thanks,
| > | > | | Marcelo Cabrera.

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bjossi - 16 Jan 2006 11:48 GMT

Hi!

I have the same problem with UserControls. I have to click twice on the
buttons on the control to make them react correctly. It seams to be the
"doPostBack" that, by some reason, isn't correct. The scenario is
as follows. The page load and 4 user controls are created all with
buttons "edit" and "delete" the "doPostBack" for the first
control has '_ctl1$...' the next has '_ctl2$...' etc (notice
the numbers 1, 2.. etc). When I click the edit button on the first
control the second control reacts. by displaying the "edit" box.
But now, when I look at the "doPostBack" for the buttons the first
control has '_ctl0$...' the second has '_ctl1$...' etc (the
numbers start from 0) and now the buttons work for correct control.
This implies that there is a problem with associating the correct
control Id with the controls the first time they load. Why it is so
I'm not able to find out.

Dose anyone have an idea how to solve this (have you Marcelo solved
your problem) ???

Thanks...
Björn Erlendsson

Marcelo Cabrera skrev:

> Hi,
>
[quoted text clipped - 15 lines]
> Thanks,
> Marcelo Cabrera.

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Marcelo Cabrera - 19 Jan 2006 16:18 GMT

I "fixed" it by loading some javascript after processing the event. The
javascript code will produce another 'postback' wihtout defining the control
who did it, then when the user click on a control is like if it was clicked
twice.

<asp:panel id="refreshscript_panel" visible="False" runat="server"
enableviewstate="False">
<script language="javascript" type="text/javascript">
//__doPostBack('','');
document.forms[0].submit();
</script>
</asp:panel>

just show the panel after the code handling events in your control and you
will be ok, but beware that this will produce two postbacks.

> Hi!
>
[quoted text clipped - 40 lines]
> > Thanks,
> > Marcelo Cabrera.

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bjossi - 16 Jan 2006 11:49 GMT

> Hi,
>
[quoted text clipped - 15 lines]
> Thanks,
> Marcelo Cabrera.

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PreInit event in usercontrol

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