Question

这是我父组件的html模板。自定义标记用于包含我的子组件以显示帖子对象我已连接快速服务器，所有查询都是通过HTTP与服务完成的。每次添加新的帖子对象时，UI都不会更新。

我知道我需要将事件传递给子组件，但到目前为止我还没有成功。

/ * app.component.html * / 在这个模板中我试图用（onAdded）=“onAdded（$ event）”

绑定方法

<div class="collapse navbar-collapse" id="navbarSupportedContent">

    <ul class="navbar-nav mr-auto links">   
      <li class="nav-item">
        <a class="btn btn-secondary" routerLink="/posts" href="javascript:void(0);" (click)="addToBoard()"> <i class="fa fa-plus-square fa-3x" aria-hidden="true"></i></a>
      </li>
    </ul>

  </div>

</div>

的

/ * app.component.ts（PARENT）* /

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,)   
  }

}

/ view-board.component.ts（CHILD） /

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);
  }**

}

感谢您的帮助！

Answer 1

不，如果你想从Child传递给Parent，你必须做事件发送，在这种情况下，你可以作为输入传递给子元素。

内部父组件。

<view-board [success]="success">

并在您的子组件中

@Input() success: string;

Angular 4 - 从父组件到子组件的事件绑定

1 个答案: