Maintaining state with a dynamically created TemplateColumn

[Pete Moss]

During a postback event, I am having trouble retrieving the state of a
CheckBox Control that I am dynamically adding to a DataGrid Control using
ASP.NET 1.1.

I have no trouble adding the TemplateColumn dynamically. I persist a DataSet
in my Session object and I bind the CheckBox to the DataSet. So far so good.
The CheckBoxes show up and the user interacts with them (checks a few,
unchecks a few).

The problem is that during a postback event, I want to update the DataSet
with the results of what the user did to those CheckBoxes. Problem is, that
during postback (eg, when a Button is clicked), the DataGrid.Items collection
and DataGrid.Columns collection no longer has any knowledge of the
dynamically added TemplateColumn.

I tried setting the CheckBox.EnableViewState = true when I create the
TemplateColumn, but I can't figure out how to get at the dynamically added
CheckBox Controls during postback. Anyone know how to do this?

I have no trouble if I declaratively add the CheckBox TemplateColumns. If I
do that, I can get exactly what I want during postback. But no go when I
create the TemplateColumns dynamically.

Thanks,
Pete

[Phillip Williams]

You have to create dynamically controls upon each postback during the
page.init event handling.

I have a sample code in asp.net 1.1
http://www.societopia.net/Samples/Da...Delegates.aspx

and another in asp.net 2.0
http://www.webswapp.com/codesamples/...e/default.aspx
--
HTH,
Phillip Williams
http://www.societopia.net
http://www.webswapp.com
"Pete Moss" wrote:

During a postback event, I am having trouble retrieving the state of a
CheckBox Control that I am dynamically adding to a DataGrid Control using
ASP.NET 1.1.

I have no trouble adding the TemplateColumn dynamically. I persist a DataSet
in my Session object and I bind the CheckBox to the DataSet. So far so good.
The CheckBoxes show up and the user interacts with them (checks a few,
unchecks a few).

The problem is that during a postback event, I want to update the DataSet
with the results of what the user did to those CheckBoxes. Problem is, that
during postback (eg, when a Button is clicked), the DataGrid.Items collection
and DataGrid.Columns collection no longer has any knowledge of the
dynamically added TemplateColumn.

I tried setting the CheckBox.EnableViewState = true when I create the
TemplateColumn, but I can't figure out how to get at the dynamically added
CheckBox Controls during postback. Anyone know how to do this?

I have no trouble if I declaratively add the CheckBox TemplateColumns. If I
do that, I can get exactly what I want during postback. But no go when I
create the TemplateColumns dynamically.

Thanks,
Pete

[Pete Moss]

Phillip,

Thanks for the reply and the sample,but appears that your sample is doing
something different and is doing a postback on each CheckBox click. That is
what I am trying to avoid.

I believe I found a solution, however. The trick seemed to be in re-creating
the TemplateColumns during the LoadViewState() override on the page. It
simply looks like this:

protected override void LoadViewState(object savedState)
{
base.LoadViewState (savedState);

CreateTemplateColumns();
}

Once that is done, in a postback event such as a button click, the state of
all DataGrid columns is available to me.

The only annoying thing from my POV is that I have to make sure I update the
DataSet with the current CheckBox states in the TemplateColumns. Otherwise,
I lose the state of the CheckBox when the DataGrid gets updated.

Pete

"Phillip Williams" wrote:

You have to create dynamically controls upon each postback during the
page.init event handling.

I have a sample code in asp.net 1.1
http://www.societopia.net/Samples/Da...Delegates.aspx

and another in asp.net 2.0
http://www.webswapp.com/codesamples/...e/default.aspx
--
HTH,
Phillip Williams
http://www.societopia.net
http://www.webswapp.com