角@ViewChild()错误:预期有2个参数，但得到1个

问题描述

尝试使用ViewChild时出现错误.错误是未提供'opts'的参数."

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

@ViewChild都给出了错误.

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);
  }

}

推荐答案

在Angular 8中，ViewChild需要2个参数

In Angular 8 , ViewChild takes 2 parameters

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

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