User Control and Page Events

  • Thread starter Thread starter Guest
  • Start date Start date
G

Guest

Ok...I've been looking for an answer to this problem and can't seem to find
one...Framework 1.1 mind you.

I have a base class that inherits from UserControl. I have 5 and soon to be
12 user controls that derive from this base class that represent US States
with appropriate business logic and rules. Inside the base class is an event
that is raised whenever you click a checkbox in the datagrid of each of the
user controls...no biggie... This event is to be seen by the page so that it
can take appropriate action upon handling the event (such as disabling
selections, etc...) however the page cannot see this event to handle it.

Now another event needs to be fired by the page when you make a selection in
one or more dropdowns that are then handled by each of the user controls as
appropriate. For example, if one dropdown value gets selected, each state
user control will compare its business rules to the selection and uncheck a
checkbox in its grid if the rules dictate. However, this event is never seen
by the control.

My problem is that I don't know where to define these events so that the
page and the controls can see and use them. The UC event i've defined in the
baseclass so that all the derived controls can access it through a protected
method. However, I cannot construct a handles on the page because the page
can't see it. Likewise I cannot construct a handles in the controls because
they cannot see the page event.

Any ideas or need for further info?
 
Likewise I cannot construct a handles in the controls because
they cannot see the page event.
Any ideas or need for further info?
Click to expand...

What about this idea:

1. You define a Notification List (NL) on the page for each event you need
to handle (or one list for all events):

public ArrayList NotificationList = new ArrayList();

2. Each UC has one base class, wich in its OnLoad method registers itself in
the NL:

public class MyBaseControl: UserControl
{
override OnLoad()
{
if (Page != null) (Page as MyBasePage).NotificationList.Add(this);
}

public HandlePageEvent(EventArgs e)
{
DoSomething();
}
}

3. When you have an event on a page, you do something like this:

protected MyList_SelectedIndexChanged(EventArgs e)
{
foreach (MyBaseControl control in NotificationList)
control.HandlePageEvent(e);
}

So, all your UC will see the page's events.

PS. I typed directly into this window, so, it is a "psevdocode".
 
That is what I wanted to avoid actually. But it may be the only way I can
achieve what I want to do. I do similar stuff elsewhere but it doesn't seem
as elegant as just doing it all with events and not making methods that
iterate over all the controls when each control could just subscribe the the
event as needed.

I would rather do this with pure events. It seems that if you don't derive
from a base class then event handling is 1:1. However, as soon as I started
deriving then the whole event model blew up because nothing can see the
other's events. Which seems counterintuitive.

Thanks for the input - any other ideas?
 
Thanks for the input - any other ideas?

Maybe the UC can add their own event handlers to the Page's controls?
Something like this:

public class MyBaseControl: UserControl
{
override OnInit()
{
base.OnInit();

if (Page != null) (Page.MyList.SelectedIndexChanged += new
EventHandler(MyList_SelectionChanged);
}

void MyList_SelectionChanged(object sender, EventArgs e)
{
DoSomething();
}
}
 
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