Maintaining state for a programatically loaded control

I've written several UserControls that contain different versions of a form
that users need to fill out. Depending on which role a user is logged in as,
I load the appropriate UserControl and add it to a panel on my WebForm. So
far, so good. However, when the form is posted back to the server, I'm
getting stuck.

I don't think I want to load the control into the panel again because then
all of the values that were set by the user before posting back will be lost.
Still, I have to get an instance of the control somehow.

I thought maybe I'd stuff the entire UserControl into the ViewState (the
user controls are not very big), but then I get an error message saying, "The
type 'ASP.MyDataEntryForm_ascx' must be marked as Serializable or have a
TypeConverter other than ReferenceConverter to be put in viewstate." I've put
a [Serializable] attribute on the control's class, but it doesn't seem to
help. The control only contains other WebControls, all of which can have
ViewState enabled.

Any ideas, or should I go for a completely different approach like
redirecting to different pages instead of loading different controls into a
single page? Thanks!Hi P:

Actually: you DO want to reload the user control on each postback
during the Load event. The controls will pick up the values correctly
from the ViewState and Form elements.

HTH,
--
Scott
http://www.OdeToCode.com/blogs/scott/

On Wed, 20 Oct 2004 00:21:03 -0700, "P. Gruenhagen"
<PGruenhagen@.discussions.microsoft.com> wrote:

>I've written several UserControls that contain different versions of a form
>that users need to fill out. Depending on which role a user is logged in as,
>I load the appropriate UserControl and add it to a panel on my WebForm. So
>far, so good. However, when the form is posted back to the server, I'm
>getting stuck.
>I don't think I want to load the control into the panel again because then
>all of the values that were set by the user before posting back will be lost.
>Still, I have to get an instance of the control somehow.
>I thought maybe I'd stuff the entire UserControl into the ViewState (the
>user controls are not very big), but then I get an error message saying, "The
>type 'ASP.MyDataEntryForm_ascx' must be marked as Serializable or have a
>TypeConverter other than ReferenceConverter to be put in viewstate." I've put
>a [Serializable] attribute on the control's class, but it doesn't seem to
>help. The control only contains other WebControls, all of which can have
>ViewState enabled.
>Any ideas, or should I go for a completely different approach like
>redirecting to different pages instead of loading different controls into a
>single page? Thanks!
Thanks, HTH. That worked, of course.

It just seems counter-intuitive to me that you would create a new instance
of the dynamically created control and add it to the page every time the page
is hit. I thought this would've caused the control values set by the user to
be lost. I was wrong.

"Scott Allen" wrote:

> Hi P:
> Actually: you DO want to reload the user control on each postback
> during the Load event. The controls will pick up the values correctly
> from the ViewState and Form elements.
> HTH,
> --
> Scott
> http://www.OdeToCode.com/blogs/scott/
> On Wed, 20 Oct 2004 00:21:03 -0700, "P. Gruenhagen"
> <PGruenhagen@.discussions.microsoft.com> wrote:
> >I've written several UserControls that contain different versions of a form
> >that users need to fill out. Depending on which role a user is logged in as,
> >I load the appropriate UserControl and add it to a panel on my WebForm. So
> >far, so good. However, when the form is posted back to the server, I'm
> >getting stuck.
> >I don't think I want to load the control into the panel again because then
> >all of the values that were set by the user before posting back will be lost.
> >Still, I have to get an instance of the control somehow.
> >I thought maybe I'd stuff the entire UserControl into the ViewState (the
> >user controls are not very big), but then I get an error message saying, "The
> >type 'ASP.MyDataEntryForm_ascx' must be marked as Serializable or have a
> >TypeConverter other than ReferenceConverter to be put in viewstate." I've put
> >a [Serializable] attribute on the control's class, but it doesn't seem to
> >help. The control only contains other WebControls, all of which can have
> >ViewState enabled.
> >Any ideas, or should I go for a completely different approach like
> >redirecting to different pages instead of loading different controls into a
> >single page? Thanks!
>