With Angular how to fill the canvas of a base component from a child component using template inheritance

Issue

I have a base component with a canvas in it. I can fill the canvas a solid colour in the ngOnInit method of this base class.

I have a child component which inherits the template of the base. I try to call the base's canvas fill method from the child's ngAfterViewInit method but it says that the canvas element is null.

I have put in alert messages and they are coming up in the order I expect. The first is in the ngOnInit method of the base and the second in the base's fillCanvas method which I call from the child's ngAfterViewInit method.

I have the code in StackBlitz here:

Code Example

Can anyone help show me what I have done wrong \ need to do so as to be able to achieve filling of the canvas from the child?

Solution

I dont think you need inheritance here, you can just call the function from the viewChild of that element, example below!

child

import { ViewChild } from '@angular/core';
import { Component, AfterViewInit } from '@angular/core';
import { BaseComponent } from '../base/base.component';

@Component({
  selector: 'app-child',
  templateUrl: './child.component.html',
})
export class ChildComponent implements AfterViewInit {
  @ViewChild(BaseComponent) base: BaseComponent;
  constructor() {}

  ngAfterViewInit() {
    this.base.fillCanvas();
  }
}

child html

<app-base [templateRef]="childTemplate"></app-base>

<ng-template #childTemplate> Child's extended template </ng-template>

stackblitz

Answered By - Naren Murali