FindControl needs an explaination!

[rsdev]

Hi,

I am using FindControl to access dynamically loaded user controls. I'm sure I've got it all wrong as I'm new to .NET.

Currently if I want to access a button or view mode in a user control nested in a page nested in a master page. I have to use this method to find the control.

FormView viewFC1 = (FormView)this.FindControl("UpdatePanelFC").FindControl("DetailsViewFC1");
            viewFC1.ChangeMode(FormViewMode.Edit);

This doesn't seem like the best way.

Can anyone please explain.

[rsdev]

HI Again,

What I mean is there a way of assigning an ID in the code behind class to reference controls that are layered deep into the page?

Thanks again.

[Shashi Sadasivan]

HI Again,

What I mean is there a way of assigning an ID in the code behind class to reference controls that are layered deep into the page?

Thanks again.

Controls burried under somthing else will need to be fished out the same way you burried them

FormView viewFC1 = (FormView)this.FindControl("UpdatePanelFC").FindCo ntrol("DetailsViewFC1");

from that I presume UpdatePanelFc is not a dynamically created control

you can shorten that piece of code using by

FormView viewFC1 = (FormView)thisUpdatePanelFC.FindControl("DetailsViewFC1");

cheers

[rsdev]

Thanks for responding Shashi.

I am using a BasePage class for most of my methods/event handlers etc. Because they are used by lots of different user controls. The user controls are loaded into the page dynamically when they page is built. I have managed to assign them IDs when I load each control.

My ignorance starts to show when I am trying to access controls inside updatepanels inside user controls that have been dynamically loaded. I know there is a Controls Collection but when I try to recursively look through the collection to find a control I get errors.

The second problem I am having is that I have set my updatepanels inside each control to conditional. I want to an event in one user control to trigger an update in all the updatepanels. But these updatepanels are inside user controls that are positioned randomly on the page.

I need to find a way to access controls and updatepanels without using long strings of FindControl.

Any small examples to point me in the right direction would be appreciated.

Controls burried under somthing else will need to be fished out the same way you burried them

FormView viewFC1 = (FormView)this.FindControl("UpdatePanelFC").FindCo ntrol("DetailsViewFC1");

from that I presume UpdatePanelFc is not a dynamically created control

you can shorten that piece of code using by

FormView viewFC1 = (FormView)thisUpdatePanelFC.FindControl("DetailsViewFC1");

cheers

[rsdev]

My answer lies somewhere in the ControlCollection. I have been playing around with this code but cannot get it to work!

foreach (Control c in Master.Controls)
            {
                    foreach (UpdatePanel up in c.Controls)
                    {
                        if (up is UpdatePanel)
                        {
                            up.Update();
                        }
                    }
}

Any ideas!

[Plater]

How do you know it doesn't work?
That update() function might be getting called (unless you set a breakpoint and it didn't) but the results of that function call get overwritten by something else happening, like maybe in the page_load() function?

[rsdev]

Hi Plater,

Thanks for responding.

In debug mode I get:

Unable to cast object of type 'System.Web.UI.HtmlControls.HtmlTitle' to type 'System.Web.UI.UpdatePanel'.

For {UpdatePanel up}

And 'up' is subsequnetly null. I think it loops infinitley unable to cast the objects.

I don't understand enough to know how to rectify this problem and if I do whether it will then update all the updatepanels on a page?!

Thanks for your help.

[Shashi Sadasivan]

//invoke this method from a method of yours by using this.updateControl(this);
private void updateControl(Control cntrl)
{
   foreach(Control c in cntrl)
   {
       if(c.HasChildren)
          this.updateControl(c);
      else
      {
          UpdatePanel up;
          if(c.getType() == up.GetType())
          {
              up = (UpdatePanel)c;
              up.Update();
          } 
      }        
   }
}

Try using this....
I have found issues with casting...so i declare a variable of that type i amlooking for and let the system return its type.

Hope this works

cheers

[rsdev]

Hi Shashi,

Thank you for your response.

How do you get round the error that the up variable is unassigned?

This is close.

[rsdev]

Hi Shashi,

Thanks again I got it work. Excellent! You star.

private void updateControl(Control cntrl)
        {
            UpdatePanel up = new UpdatePanel();
            foreach (Control c in cntrl.Controls)
            {
                if (c.HasControls())
                {
                    if (c.GetType() == up.GetType())
                    {
                        up = (UpdatePanel)c;
                        up.Update();
                    }
                    this.updateControl(c);
                }
                else
                {
                    if (c.GetType() == up.GetType())
                    {
                        up = (UpdatePanel)c;
                        up.Update();
                    }
                }
            }
        }

//to call method this.updateControl(Master);

I suppose the only draw back is creating a new UpdatePanel object everytime I want to refresh the panels. A little messy. Maybe I can find another way.

Thanks though excellent code:)

[rsdev]

Then to answer my original post. Check this out:

//Find Control recursively
 
        public static Control findControl(string id, Control col)
        {
            foreach (Control c in col.Controls)
            {
                Control child = findControlRecursive(c, id);
                if (child != null)
                    return child;
            }
            return null;
        }
 
        private static Control findControlRecursive(Control root, string id)
        {
            if (root.ID != null && root.ID == id)
                return root;
 
            foreach (Control c in root.Controls)
            {
                Control rc = findControlRecursive(c, id);
                if (rc != null)
                    return rc;
            }
            return null;
        }

[Yordan Georgiev]

public static Control FindControlRecursive ( ref Control root , string id )
{
try
{
if (root.ID == id)
{
return root;
} //eof if

for (int i = 0; i < root.Controls.Count; i ++ )
{

Control c = new Control ();
c = root.Controls [ i ];
Control t = FindControlRecursive ( ref c , c.ID.ToString() );
if (t != null)
{
return t;
} //eof if
} //eof foreach
} //eof try
catch (Exception e)
{
Utils.Debugger.WriteIf ( "The following Exception occured : \n" + e.Message );
return null;
} //eof catch

return null;
} //eof FindControlRecursive

[Plater]

I don't see any reason to pass it by reference, you're not making changes to it, and even if you did, they would still "take".
Unless you want to maybe cut down on memory usage?