Angular Tree Component: get top level parent of current node

Question

I want to find the top-level parent (on the tree) of the current node.

I have the following code:

expandParents(node: any) {
    const parent = node.data.x.parent;

    if (!!parent && this.getLevel(parent) > 0) {
      this.expandParents(parent);
    } else if (!!parent && this.getLevel(parent) === 0) {
      console.log('1. ', parent);
      return parent;
    }
  }

  getTopLevelParent(node: T) {
    const topLevelParent = this.expandParents(node);

    console.log('2. ', topLevelParent);
    return topLevelParent;
  }

Below, is what console.log prints:

1.  DynamicFlatNode {data: {…}}
2.  undefined

Why console.log('2. ', topLevelParent); always returns undefined?

getTopLevelParent this function called two times that's why 2. is getting undefined — Aman Gojariya, Feb 23 '23 at 08:23
Replace this **const parent = node.data.x.parent;** code to **const parent = node.data.x.parent ? node.data.x.parent : node;** — Aman Gojariya, Feb 23 '23 at 08:26
@AmanGojariya hmm.. still get the same result (undefined) :\ — George Perid, Feb 23 '23 at 08:30
can you please share code where you have call **getTopLevelParent** this function? — Aman Gojariya, Feb 23 '23 at 08:31
@AmanGojariya seems that the last part of code that is executed is the if statement (not the else). I cannot understand how the parent of a node with level 0 corresponds to a node with level > 0 . — George Perid, Feb 23 '23 at 08:34
@AmanGojariya onChangeEvent(event, node: any) { const topLevelParent = this.treeControl.getTopLevelParent(node); console.log('Top-level parent: ', topLevelParent); } — George Perid, Feb 23 '23 at 08:35
@AmanGojariya still gets undefined. This code seems to be a mystery. : ) Nevertheless, thanks a lot for your help! — George Perid, Feb 23 '23 at 08:47

score 0 · Answer 1 · answered Feb 23 '23 at 08:41

Maybe, somewhere you're getting undefined data so can you please try using below code

expandParents(node: any) {
  const parent = node.data && node.data.x && node.data.x.parent ? node.data.x.parent : node;

  if (!!parent && this.getLevel(parent) > 0) {
    this.expandParents(parent);
  } else if (!!parent && this.getLevel(parent) === 0) {
    console.log('1. ', parent);
    return parent;
  }
}

getTopLevelParent(node: T) {
  if (node) {
    const topLevelParent = this.expandParents(node);

    console.log('2. ', topLevelParent);
    return topLevelParent;
  }
}

Angular Tree Component: get top level parent of current node

1 Answers1