angular - How to access the nativeElement of a Component in Angular4?

Question

I have two components and one with attribute selector. The child component is,

import { Component, OnInit, Input, ElementRef } from '@angular/core';


@Component({
    selector: '[app-bar-chart]',
    templateUrl: './bar-chart.component.html',
    styleUrls: ['./bar-chart.component.css']
})
export class BarChartComponent implements OnInit {

    @Input() chartContainer: ElementRef;
    @Input() title: string;
    @Input() chartData: {
        title: string,
        content: {
            label: string,
            value: number,
            fill?: string
        }[]
    }[];

    constructor() { }

    ngOnInit() {
        console.log(this.chartContainer);
        console.log(this.chartContainer.nativeElement);
    }

}

The parent component is,

import { Component, OnInit, Output, ViewChild, ElementRef } from '@angular/core';

@Component({
    selector: 'app-dashboard',
    template: `<div><div class="graph-image" style="width: 100%; height: 400px;" app-bar-chart [title]="barChartTitle" [chartData]="ChartData" [chartContainer]="chartContainer" #chartContainer></div></div>`,
    styleUrls: ['./dashboard.component.css']
})
export class DashboardComponent implements OnInit {
    barChartTitle = 'Transaction History';
    ChartData = [
        {
            "title": "May2017",
            "content": [
                {
                    "label": "payable",
                    "value": 10
                }
            ]
        },
        {
            "title": "Jun2017",
            "content": [
                {
                    "label": "payable",
                    "value": 120
                }
            ]
        }
    ];
    constructor() { }

    ngOnInit() {
    }

}

I am passing the local reference from the parent component to the child component. When I am consoling the native element of this local reference it is 'undefined'. How can I access the native element so that I can access the style width and height of the component div.

Answer 1

If you need the ElementRef of a component, you can't use a template variable. If the element is a component, you'll get the component instance instead. A template variable only returns ElementRef for plain HTML elements.

To get ElementRef of a component, you need to use @ViewChild()

@ViewChild('chartContainer', { read: ElementRef }) myChartContainer:ElementRef;

and then pass it along with

[chartContainer]="myChartContainer"

I would make the input a setter

 private _chartContainer:ElementRef;
 @Input() 
 set chartContainer(value: ElementRef) {
   this._chartContainer = value;
   console.log(this.chartContainer);
   console.log(this.chartContainer.nativeElement);
 }

but ngOnInit works as well Plunker example