角度4-从父组件到子组件的事件绑定

import { Component, OnInit, **EventEmitter, Output**} from '@angular/core';
import { Post } from './shared/post';
import { PostService } from './services/post.service';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
  providers: [PostService]
})
export class AppComponent implements OnInit  {
  @Output() onAdded = new EventEmitter<Post>();
  title = 'Post it Board';
  posts: Post[];
  private newPost :Post;
  constructor(private postService: PostService) { }

  ngOnInit(): void {
    this.getPosts()
    this.newPost = {
      text: 'some text',
      _id: ''

    }
  }


  addToBoard(): void {
    this.postService.addPost(this.newPost).subscribe(
      response=> {
          if(response.success== true)
             //If success, update the view-list component
             console.log('success')
             **this.onAdded.emit(this.newPost);**
      },
   );
  }

  getPosts() {
    this.postService.getAllPosts().subscribe(
        response => this.posts = response,)   
  }

}

/ 查看板。组成部分ts(儿童) /

import { Component, OnInit} from '@angular/core';
import { Post } from '../shared/post';
import { POSTS } from '../shared/mock-posts';
import { PostService } from '../services/post.service';

@Component({
  selector: 'view-board',
  templateUrl: './view-board.component.html',
  styleUrls: ['../css/style.css'],
  providers: [PostService]
})
export class ViewBoardComponent implements OnInit {

  title = "Post it"
  posts: Post[];
  constructor(private postService: PostService) { }

  ngOnInit() {
    this.getPosts()
  }

  getPosts() {
    this.postService.getAllPosts().subscribe(
        response => this.posts = response,)   
  }

  **onAdded(post: Post) {
    console.log('new post added ' + post.text)
    this.posts = this.posts.concat(post);
  }**

}

谢谢你的帮助!