Angular @ViewChild() error: Expected 2 arguments, but got 1

Question

When trying ViewChild I am getting the error. Error is "An argument for 'opts' was not provided."

Both @ViewChild is giving the error.

import { Component, OnInit, ElementRef, ViewChild, Output, EventEmitter } from '@angular/core';
import { Ingredient } from 'src/app/shared/ingredient.model';

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

@ViewChild('nameInput') nameInputRef: ElementRef;
@ViewChild('amountInput') amountInputRef: ElementRef;
@Output() ingredientAdded = new EventEmitter<Ingredient>();
  constructor() {}

  ngOnInit() {
  }

  onAddItem() {
    const ingName = this.nameInputRef.nativeElement.value;
    const ingAmount = this.amountInputRef.nativeElement.value;
    const newIngredient = new Ingredient(ingName, ingAmount);
    this.ingredientAdded.emit(newIngredient);
  }

}

ts(11,2): error TS2554: Expected 2 arguments, but got 1.

Answer 1

In Angular 8 , ViewChild takes 2 parameters

 @ViewChild(ChildDirective, {static: false}) Component

Answer 2

Angular 8

In Angular 8, ViewChild has another param

@ViewChild('nameInput', {static: false}) component : Component

You can read more about it here and here

Angular 9 & Angular 10

In Angular 9 default value is static: false, so doesn't need to provide param unless you want to use {static: true}

Answer 3

In Angular 8 , ViewChild takes 2 parameters:

Try like this:

@ViewChild('nameInput', { static: false }) nameInputRef: ElementRef;

Explanation:

{ static: false }

If you set static false, the child component ALWAYS gets initialized after the view initialization in time for the ngAfterViewInit/ngAfterContentInit callback functions.

{ static: true}

If you set static true, the child component initialization will take place at the view initialization at ngOnInit

By default you can use { static: false }. If you are creating a dynamic view and want to use the template reference variable, then you should use { static: true}

For more info, you can read this article

Working Demo

In the demo, we will scroll to a div using template reference variable.

 @ViewChild("scrollDiv", { static: true }) scrollTo: ElementRef;

With { static: true }, we can use this.scrollTo.nativeElement in ngOnInit, but with { static: false }, this.scrollTo will be undefined in ngOnInit , so we can access in only in ngAfterViewInit

Answer 4

it is because view child require two argument try like this

@ViewChild('nameInput', { static: false, }) nameInputRef: ElementRef;

@ViewChild('amountInput', { static: false, }) amountInputRef: ElementRef;

Answer 5

In Angular 8, ViewChild always takes 2 param, and second params always has static: true or static: false

You can try like this:

@ViewChild('nameInput', {static: false}) component

Also,the static: false is going to be the default fallback behaviour in Angular 9.

What are static false/true: So as a rule of thumb you can go for the following:

• { static: true } needs to be set when you want to access the ViewChild in ngOnInit.

  { static: false } can only be accessed in ngAfterViewInit. This is also what you want to go for when you have a structural directive (i.e. *ngIf) on your element in your template.

Answer 6

Regex for replacing all via IDEA (tested with Webstorm)

Find: \@ViewChild\('(.*)'\)

Replace: \@ViewChild\('$1', \{static: true\}\)

Answer 7

you should use second argument with ViewChild like this:

@ViewChild("eleDiv", { static: false }) someElement: ElementRef;

Answer 8

Use this

@ViewChild(ChildDirective, {static: false}) Component

Answer 9

Try this in angular 8.0:

@ViewChild('result',{static: false}) resultElement: ElementRef;

Answer 10

In Angular 8, ViewChild has another param

@ViewChild('nameInput', {static: false}) component

I resolved my issue like below

@ViewChild(MatSort, {static: false}) sort: MatSort;

Answer 11

That also resolved my issue.

@ViewChild('map', {static: false}) googleMap;