How to get a label value from web user control to a content page using master page

Question

I have a web user control book.ascx and a formview:

Answer 1

I guess the way to achieve what you want is to let the book-control fire an event after it knows what the value is.

You now need to gain access from the page to the value inside the control. That can be achieved by exposing the value via a property or you can create your own EventArgs and throw an Event.

public class StringEventArgs:EventArgs
{
  public String Value {get; private set;}  
  public StringEventArgs(String val){ this.Value = val; }
}

Answer 2

From the code behind in the Default.aspx.cs:

protected void fv_OnDataBound(object sender, EventArgs e) 
{
    Label fvLabel = (Label)fv.FindControl("bookID");
    lblBookId.Text = fvLabel.Text;
}

Answer 3

you wanted to get it on the client side via javascript?

getElementById('<%=lblBookId.ClientID%>')

I would also recommend getting firebug for firefox and then you can take a look at the generated html of the webpage. You'll also be able to step though and debug your javascript.

if trying to find this on the server side try this.

ContentPlaceHolder ph = Page.Master.FindControl("ContentPlaceHolder1");   
UserControl Uc = ph.Controls(0);
FormView fv = up.FindControl("fv");
Label label = fv.FindControl("lblBookId");
label.Text = "Hi there"; 

if this doesn't work, you can get the idea. keep drilling down until you find what you're looking for.