On which Page life cycle are the Client IDs generated?

Question

i am programatically adding Webcontrols in to a User Control i am also adding a javascript event passing the controlID as a parameter but the clientID is the one i assigned a it does not contain the one that asp.net generates

   var txt = new TextBox();
   txt.ID = "MyID"+Number;

   chkBox.Attributes.Add("onClick", "EnableTxtBox('" +txt.ClientID + "');");

i can workAround this by adding the parent control ID

   chkBox.Attributes.Add("onClick", "EnableTxtBox('" + this.ClientID+"_"+txt.ClientID + "');");

On which Page life cycle are the Client IDs generated?

Answer 1

You need to add the control to the control hierarchy before you add the attribute.

   var txt = new TextBox();
   txt.ID = "MyID"+Number;
   Controls.Add ( txt );
   chkBox.Attributes.Add("onClick", "EnableTxtBox('" +txt.ClientID + "');");

ControlCollection is no ordinary collection; it notifies the owner control when controls are added, and the control can take appropriate actions.

Answer 2

You should be able to add the attribute during OnPreRender(). INamingContainer is so painful sometimes...