How to add handler to event of controls in Template of a TemplatedControl?

[jyswjjgdwtdtj]

For example I want to bind a method to the Click event of my button (please don't tell me to use Command, for this way is not general for all the events), and the button is multiple nested by serveral templates, including datatemplate, controltemplate.

[stevemonaco]

With one level of nesting, you simply define the Button in your ControlTemplate as a required TemplatePart with a name. Then in OnApplyTemplate, you grab it via Get since it's required, and subscribe to its Click event (either myButton.Click += or via AddHandler). You can see ToggleSwitch as an example:

Avalonia/src/Avalonia.Controls/ToggleSwitch.cs

Lines 187 to 202 in cd05ff8

	protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
	{
	base.OnApplyTemplate(e);
	_switchKnob = e.NameScope.Find<Panel>("PART_SwitchKnob");
	_knobsPanel = e.NameScope.Get<Panel>("PART_MovingKnobs");
	_knobsPanel.PointerPressed += KnobsPanel_PointerPressed;
	_knobsPanel.PointerReleased += KnobsPanel_PointerReleased;
	_knobsPanel.PointerMoved += KnobsPanel_PointerMoved;
	if (IsChecked.HasValue)
	{
	UpdateKnobPos(IsChecked.Value);
	}
	}

Multiple levels of nesting is usually a design flaw. As in, Custom Control -> Another Templated Control -> Button. If "Another Templated Control" doesn't expose an event for this, you shouldn't be digging.