Question

I am relatively new to this, but here is my problem.

In asp.net, I have a parent and a child control. Within the child control I have a dropdown list. Based on dropdown list’s selected value I would like to toggle Visibility of Panel in parent control. For instance if I select Show in child control dropdown list, I need to pass true to parent control to make Panel visible and vice versa. How should I do that. I have read that can be done via the event handling and have seen certain scenarios but I am not clear on that. Please help!

Thanks.

Answer 1

Raise an event that your parent control listens for.

In the code behind for your parent control, create an object of the type of your child control. Something like:

private MyWebControl childControl;

Then in the child control, define an event

public event System.EventHandler SelectionChanged;

In the OnIndexChanged event of your DropDownList, after you do your processing, raise your event:

if(this.SelectionChanged!= null)
{
     this.SelectionChanged(this, new EventArgs()); 
     // You can send the index of the DDL in the event args
}

In your parent control, wire up the event. Page_Init is good

this.childControl.SelectionChanged+=new EventHandler(childControl_SelectionChanged);

Still in the parent control, define your method

private void childControl_SelectionChanged(object sender, EventArgs e)
{
      /// Do your processing here.
      /// Grab the DDL's index from the EventArgs and do your processing

}

Should be all you need to get it working!