Failed to load viewstate - user controls

[Rotsey]

Hi,

I have a web site that uses user controls to display different formats of
timesheets.

I have a browse page that has prev/next buttons to browse through a set of
timesheets.

As I say they can be different user controls for each timesheet type.

The problem is when I navigate (prev/next) from one type of user control to
the next type
I get this error

System.Web.HttpException: Failed to load viewstate. The control tree into
which viewstate is being loaded must match the control tree that was used to
save viewstate during the previous request. For example, when adding
controls dynamically, the controls added during a post-back must match the
type and position of the controls added during the initial request.

The thing is strange is that say the first user control is for monthly
timesheets and then I click next to goto
a weekly timesheet (different user control) it is fine. But when i go back
to the first monthly timsheet
again it gives this error.

Help!!
rotsey

[bruce barker]

when viewstate is loaded after a postback, it looks for controls with
the same name and type to load.

if you dynamically change the user control you can get this error. you
should keep track of which control you rendered (say a flag in
viewstate) and recreate the control in oninit. then in onload/prerender
if you change the control, delete the old one and add the new one.

-- bruce (sqlwork.com)

Rotsey wrote:

Hi,

I have a web site that uses user controls to display different formats of
timesheets.

I have a browse page that has prev/next buttons to browse through a set of
timesheets.

As I say they can be different user controls for each timesheet type.

The problem is when I navigate (prev/next) from one type of user control to
the next type
I get this error

System.Web.HttpException: Failed to load viewstate. The control tree into
which viewstate is being loaded must match the control tree that was used to
save viewstate during the previous request. For example, when adding
controls dynamically, the controls added during a post-back must match the
type and position of the controls added during the initial request.

The thing is strange is that say the first user control is for monthly
timesheets and then I click next to goto
a weekly timesheet (different user control) it is fine. But when i go back
to the first monthly timsheet
again it gives this error.

Help!!
rotsey

[SMiGL]

On Dec 4, 4:31 am, "Rotsey" <[e-mail]>
wrote:

Hi,

I have a web site that uses user controls to display different formats of
timesheets.

I have a browse page that has prev/next buttons to browse through a set of
timesheets.

As I say they can be different user controls for each timesheet type.

The problem is when I navigate (prev/next) from one type of user control to
the next type
I get this error

System.Web.HttpException: Failed to load viewstate. The control tree into
which viewstate is being loaded must match the control tree that was used to
save viewstate during the previous request. For example, when adding
controls dynamically, the controls added during a post-back must match the
type and position of the controls added during the initial request.

The thing is strange is that say the first user control is for monthly
timesheets and then I click next to goto
a weekly timesheet (different user control) it is fine. But when i go back
to the first monthly timsheet
again it gives this error.

Help!!
rotsey

This problem arise when you dynamic create child control and for this
create use some variable. After postback this variable has old value
that give at Initialize method. To fix this problem need recover this
varible, for this use SaveControlState, LoadControlState.

Example
public class UniversalFilterControl1 : WebControl
{

protected override void OnInit(EventArgs e)
{
base.OnInit(e);
Page.RegisterRequiresControlState(this);
}

protected override void LoadControlState(object savedState)
{
object[] list = savedState as object[];
base.LoadControlState(list[0]);
if (list[1] != null)
<some varible= list[1];
}

protected override object SaveControlState()
{
object[] list = new object[2];
list[0] = base.SaveControlState();
list[1] = <some varible>;
}
}