@ViewChild: access grand-child methods

Question

I have three nested components, called level0, level1 and level2, defined like so:

@Component({
selector: 'level2',
template: `<div>I am level 2</div>`,
})
export class Level2 {
  getName(){
    return "my name is 'TWO'";
  }
}

---

@Component({
selector: 'level1',
template: `<div>I am level 1<level2></level2></div>`,
directives: [Level2]
})
export class Level1 {
  getName(){
    return "my name is 'ONE'";
  }
}

---

@Component({
selector: 'level0',
template: `<div>I am level 0<level1></level1></div>`,
directives: [Level1,Level2]
})
export class App {
@ViewChild(Level1) level1:Level1;
@ViewChild(Level2) level2:Level2;
ngAfterViewInit() {
  if(this.level1){var name1 = this.level1.getName();}
  if(this.level2){var name2 = this.level2.getName();}
  console.log("name1",name1);
  console.log("name2",name2);
  }
}

In the console, I expected to see:

name1 my name is 'ONE'
name2 my name is 'TWO'

But I see instead:

name1 my name is 'ONE'
name2 undefined

What am I missing? Why can't the Level0 component access Level2 through @ViewChild?

Is there a way to access the Level2 methods in Level0?

---

Here is the plnkr

Answer 1

It can be acheived if you use ViewChild at each level of your nested components, like this way:

// Level 2
@Component({
selector: 'level2',
template: `<div>I am level 2</div>`,
})
export class Level2 {
  getName(){
    return "my name is 'TWO'";
  }
}


// Level 1
@Component({
selector: 'level1',
template: `<div>I am level 1<level2></level2></div>`,
directives: [Level2]
})
export class Level1 {
  @ViewChild(Level2) level2:Level2;
  getName(){
    return "my name is 'ONE'";
  }

  // You need to add additional function that would be called from level 1
  calledFromLevel1() {
    return this.level2.getName();
  }
}


// Level 0
@Component({
selector: 'level0',
template: `<div>I am level 0<level1></level1></div>`,
directives: [Level1,Level2]
})
export class App {
@ViewChild(Level1) level1:Level1;
ngAfterViewInit() {
  if(this.level1) {
    var name1 = this.level1.getName();
    var name2 = this.level1.calledFromLevel1();
  }
  console.log("name1",name1);
  console.log("name2",name2);
  }
}