Query elements inside of a custom element

Question

I have two custom elements. The one of them is nested to another one. Something like this:

Answer 1

@override
void attached() { 
  // attached is an example the code an be placed somewhere else
  // but some places are executed before the childs are added 

  super.attached();

  var nodes = (shadowRoot.querySelector('content') as ContentElement).getDistributedNodes();

  var myElement = nodes.firstWhere((e) => e is MyDecorator); // not sure about this `e is MyDecorator`
  // you have to choose some way to identify the node in the result
  // I currently have no example where I can try it myself
}

if the tag has an id attribute like id='c1' then this works too

  var nodes = ($['c1'] as ContentElement).getDistributedNodes();