Find controls being rendered in master page at runtime

Question

I have a master page which has a number of controls on it both from the content page and the master page itself. All these controls extend System.Web.UI.UserControl and some implement an interface called IControlInjector.

When the master page loads, is there any way I can check in the master page what controls are being loaded in the control tree and find all those that implement the IControlInjector interface?

Answer 1

// put in code-behind class...
private void GatherIControlInjectors(Control control, IList<IControlInjector> controls){
     foreach(Control ctrl in control){
          if(ctrl is IControlInjector)
              controls.Add(ctrl);

          if(ctrl.Controls.Count > 0)
              GatherIControlInjectors(ctrl, controls);
     }
     return;
}


// example
IList<IControlInjector> ctrlInjectors = new List<IControlInjector>();
GatherIControlInjectors(Master, ctrlInjectors);

Answer 2

Instead of doing it retrospectively you could add an extension method for ControlsCollection .Add or override ControlsCollection and the add method to deal with adding controls, implementing specific interfaces, in order that you can stick them straight into a registry (for example a dictionary or list). Thereby having access to your controls in a strongly typed, quick lookup fashion.