Question

我已经找到了一些较旧的答案，但他们使用的方法已不再有效。我有一个标题组件

import { Component, OnInit } from '@angular/core';
import { Router, NavigationEnd } from '@angular/router';
import { Observable } from 'rxjs/Observable';
import 'rxjs/Rx'; 

import { AuthenticationService } from '../_services/Authentication.Service';

@Component({
  selector: 'app-header',
  templateUrl: './header.component.html',
  styleUrls: ['./header.component.css']
})
export class HeaderComponent implements OnInit {
  loading = false;
  error = '';
  isLoggedIn = false;
  showMessageWindow = false;
  messageType: string = "";
  messageText: string = "";
  public currentUser: any = null;

  constructor(private _auth: AuthenticationService, private router: Router) { }

  ngOnInit() {
    if(this._auth.isLoggedIn()) {
      this.isLoggedIn = true;
    }
    else {
      this._auth.logout();
      this.isLoggedIn = false;
      this.router.navigate(['/']);
    }
  }

  showMessage(message: string, type: string) {
    this.messageText = message;
    this.messageType = type;
    this.showMessageWindow = true;
  }
}

这是非常基本的，显示和管理可以看到的导航，具体取决于是否以及谁登录。我在标题组件中内置了警告/警报。并非所有页面都使用标题，因此我将其导入到使用它的组件中，并将<app-header></app-header>置于顶部，将其放入组件模板中。

Here is a component that uses the header.
import { Component, OnInit } from '@angular/core';
import { HeaderComponent } from '../header/Header.Component';
import { Router, ActivatedRoute } from '@angular/router';

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

  constructor( private router: Router, private activatedRoute: ActivatedRoute) { }

  ngOnInit() {

  }

}

我希望能够将一个方法放入此组件中，该方法从标头组件调用showMessage()。我尝试了几种不同的方法，但收效甚微。我最大的问题是如何引用嵌入式组件。我查看了文档，但是他们总是在组件中使用模板而不使用单独的html文件。

如果我尝试添加

  @ViewChild(HeaderComponent)
  private header: HeaderComponent;

进入我的CensusComponent我得到一个警告：

WARNING in ./src/app/header/Header.Component.ts
There are multiple modules with names that only differ in casing.
This can lead to unexpected behavior when compiling on a filesystem with other case-semantic.
Use equal casing. Compare these module identifiers:

Answer 1

使用uptime装饰工厂

perl

您收到的错误：

ViewChild

完全正交。

具体来说，这意味着当您导入header / Header.component以在// Here is a component that uses the header. import {ViewChild} from '@angular/core'; import {Component, OnInit} from '@angular/core'; import {HeaderComponent} from '../header/Header.Component'; import {Router, ActivatedRoute} from '@angular/router'; @Component({ selector: 'app-census', templateUrl: './census.component.html', styleUrls: ['./census.component.css'] }) export class CensusComponent implements OnInit { // The argument `HeaderComponent` tells the framework to bind to the child // component whose constructor function is `HeaderComponent` @ViewChild(HeaderComponent) header: HeaderComponent; constructor(readonly router: Router, readonly activatedRoute: ActivatedRoute) {} ngOnInit() { this.header.showMessage('an error occurred!', 'error'); } }中注册它时，您使用具有不同外壳的模块说明符导入了该组件。例如。 WARNING in ./src/app/header/Header.Component.ts There are multiple modules with names that only differ in casing. This can lead to unexpected behavior when compiling on a filesystem with other case-semantic. Use equal casing. Compare these module identifiers:

这是一个你可以而且应该修复的问题。只需确保所有导入都使用相同的大小写。

我建议在任何地方使用小写文件名和小写模块说明符。一个简单的搜索和替换应该照顾它。

Answer 2

您是否考虑过尝试使用ViewChild？这应该允许您获取对标头组件的引用并调用showMessage（）方法。

https://angular.io/docs/ts/latest/cookbook/component-communication.html#!#parent-to-view-child

嵌套组件中的Angular 2调用方法

2 个答案: