从Web用户控件调用父aspx页面的函数

Question

i have a aspx page on it i'm dynamically adding the web user controls in a placeholder. and know i have cancel button on the one user control and on click of that Cancel button i want to load other user control inside the aspx page (placeholder).

how can i do that, if i create an event handler in usercontrol then that become null.

thanks

Answer 1

A user control should never, ever have any kind of dependency to the page where it lives. Add an event to the control and fire it from the Cancel button event handler.

public event EventHandler CancelClicked;

protected Cancel_Click(object sender, EventArgs e)
{
  if(CancelClicked != null)
  {
    CancelClicked(this, e);
  }
}

From your page, subscribe to the controls's CancelClicked event and do whatever operation should be done on that other user control.

Answer 2

I believe the best way to achieve this would to create an event in the user control that is fired when you need it to communicate, then in the page you can subscribe to this event.

Your User Control

Put this in your control as an event variable.

public event EventHandler CancelRequested;

Then in the cancel button click event :

CancelRequested(this, new CommandEventArgs("CancelClicked", SomeVariable));

Your Page (or parent)

Then subscribe to the event in the parent page like this (when you dynamically add it in):

ctrlYourControl.CancelRequested += new EventHandler(ctrlYourControl_CancelRequested);

Declare the event handler :

void ctrlYourControl_CancelRequested(object sender, EventArgs e)
{
    // display other user control
}

Answer 3

Add this event to your user controls:

public event EventHandler CancelClicked;

Now, this method on your parent aspx page.

public void OnCancelClicked (object sender, EventArgs data)  
{  
    // do your stuffs like loading other controls and
    // whatever when event fired
}  

When you are loading your user control dynamically, add this:

var someControl = LoadControl(@"~\SomeControl.ascx") as SomeControl;
someControl.CancelClicked += new EventHandler(OnCancelClicked);

And on your user controls:

public void btnCancel_Click(object sender, EventArgs e)
{
    if(CancelClicked != null)
    {
        CancelClicked(this, e);
    }
}

This should do !