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aspx thread: User Control Postback State Question Answered
Message #1 by "Scott Guthrie" <scottgu@m...> on Thu, 22 Mar 2001 13:49:31 -0800
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Origional Question:
-----------------------------------
I have an .ASCX file that gets loaded by a parent .ASPX page using
Page.LoadControl. The .ASCX file contains a drop down list control that
has maintainstate=3Dtrue set. However on my .ASPX page that has other
form
elements that fire various events...when these events fire (and the page
reloads) my form elements in the user control (.ASCX) get reset. I guess
I
have to programmatically maintain state for those elements.
Suggestions!?
Thanks!
--Brandon
ScottGu Answer:
-----------------------------------
Hi Brandon,
The problem you are running into is that you are calling
Page.LoadControl and adding your .ASCX User Control into the page
*after* the postback process has occured (this happens right before the
Page_Load event fires). As such, the posted back values and viewstate
do not get applied to the controls within your User Control (since they
miss this process).
To fix this, try calling Page.LoadControl and adding your .ASCX User
Control within the Page_Init event instead. This event happens *before*
the postback process occurs. Adding your user control into the tree at
this point will ensure that the appropriate values/state get posted
back.
<html>
<script language=3D"VB" runat=3Dserver>
Sub Page_Init(Sender as Object, E as EventArgs)
MyPanel.Controls.Add(Page.LoadControl("MyUserControl.ascx"))
End Sub
</script>
<body>
<asp:panel id=3D"MyPanel" runat=3Dserver/>
</body>
</html>
Hope this helps,
Scott
Message #2 by "Brandon Bohling" <brandon.bohling@i...> on Thu, 22 Mar 2001 22:55:20
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Scott--
The one problem with the solution you provided is that at the time
of "Page_Init" I do not know *which* user control I am going to add
(totally dynamic). So, I am calling Page.LoadControl via the
OnSelection_Event. Any other suggestions? Oh, and btw...this is a nested
control as well. Which means I have an .ASPX page that loads in the
main .ASCX page, and that user control loads "helper" user controls files.
All this complexity so I have a "clever" report form (for web
metrics)...anytime a customer wants a new report, i simply update an xml
file and shazam...it is automatically part of the report form. woohoo! but
a pain developing! hehe
--brandon
> Origional Question:
> -----------------------------------
>
> I have an .ASCX file that gets loaded by a parent .ASPX page using
> Page.LoadControl. The .ASCX file contains a drop down list control
that
> has maintainstate=3Dtrue set. However on my .ASPX page that has other
> form
>
> elements that fire various events...when these events fire (and the page
>
> reloads) my form elements in the user control (.ASCX) get reset. I guess
> I
> have to programmatically maintain state for those elements.
> Suggestions!?
>
> Thanks!
>
> --Brandon
>
> ScottGu Answer:
> -----------------------------------
>
> Hi Brandon,
>
> The problem you are running into is that you are calling
> Page.LoadControl and adding your .ASCX User Control into the page
> *after* the postback process has occured (this happens right before the
> Page_Load event fires). As such, the posted back values and viewstate
> do not get applied to the controls within your User Control (since they
> miss this process).
>
> To fix this, try calling Page.LoadControl and adding your .ASCX User
> Control within the Page_Init event instead. This event happens *before*
> the postback process occurs. Adding your user control into the tree at
> this point will ensure that the appropriate values/state get posted
> back.
>
> <html>
>
> <script language=3D"VB" runat=3Dserver>
>
> Sub Page_Init(Sender as Object, E as EventArgs)
>
>
> MyPanel.Controls.Add(Page.LoadControl("MyUserControl.ascx"))
>
> End Sub
>
> </script>
>
> <body>
> <asp:panel id=3D"MyPanel" runat=3Dserver/>
> </body>
> </html>
>
> Hope this helps,
>
> Scott
Message #3 by "Richard Anderson" <rja@a...> on Sat, 24 Mar 2001 19:11:13 -0000
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I didnt see a reply to this question (if there was ignore this one!)...
As controls are created in a page (such as custom web controls, user
controls etc) they are eventually added to the Controls collections of a
container (eg. the page, a user control etc). When this happens, controls
'catch up' on their events. So, in theory, if you dynamically create a
control in your select event, when that control is added to a controls
collection of the container, the loadviewstate method will kick in, so your
state should be their.
Is there any way you can send me a simple repro of your problem ?
Cheers,
Rich.
----- Original Message -----
From: "Brandon Bohling" <brandon.bohling@i...>
To: "ASP+" <aspx@p...>
Sent: Thursday, March 22, 2001 10:55 PM
Subject: [aspx] Re: User Control Postback State Question Answered
> Scott--
>
> The one problem with the solution you provided is that at the time
> of "Page_Init" I do not know *which* user control I am going to add
> (totally dynamic). So, I am calling Page.LoadControl via the
> OnSelection_Event. Any other suggestions? Oh, and btw...this is a nested
> control as well. Which means I have an .ASPX page that loads in the
> main .ASCX page, and that user control loads "helper" user controls files.
> All this complexity so I have a "clever" report form (for web
> metrics)...anytime a customer wants a new report, i simply update an xml
> file and shazam...it is automatically part of the report form. woohoo! but
> a pain developing! hehe
>
> --brandon
>
>
> > Origional Question:
> > -----------------------------------
> >
> > I have an .ASCX file that gets loaded by a parent .ASPX page using
> > Page.LoadControl. The .ASCX file contains a drop down list control
> that
> > has maintainstate=3Dtrue set. However on my .ASPX page that has other
> > form
> >
> > elements that fire various events...when these events fire (and the page
> >
> > reloads) my form elements in the user control (.ASCX) get reset. I guess
> > I
> > have to programmatically maintain state for those elements.
> > Suggestions!?
> >
> > Thanks!
> >
> > --Brandon
> >
> > ScottGu Answer:
> > -----------------------------------
> >
> > Hi Brandon,
> >
> > The problem you are running into is that you are calling
> > Page.LoadControl and adding your .ASCX User Control into the page
> > *after* the postback process has occured (this happens right before the
> > Page_Load event fires). As such, the posted back values and viewstate
> > do not get applied to the controls within your User Control (since they
> > miss this process).
> >
> > To fix this, try calling Page.LoadControl and adding your .ASCX User
> > Control within the Page_Init event instead. This event happens *before*
> > the postback process occurs. Adding your user control into the tree at
> > this point will ensure that the appropriate values/state get posted
> > back.
> >
> > <html>
> >
> > <script language=3D"VB" runat=3Dserver>
> >
> > Sub Page_Init(Sender as Object, E as EventArgs)
> >
> >
> > MyPanel.Controls.Add(Page.LoadControl("MyUserControl.ascx"))
> >
> > End Sub
> >
> > </script>
> >
> > <body>
> > <asp:panel id=3D"MyPanel" runat=3Dserver/>
> > </body>
> > </html>
> >
> > Hope this helps,
> >
> > Scott
>
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