Exploring the communication between two components in Angular 2

My Angular components include:

  1. Create-Articles: used for creating articles.
  2. List Articles: utilized for listing all articles.

The parent component is the Home Component.

import { Component, OnInit } from '@angular/core';

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

  }

}
<div class="container">
    <div class="row">
        <div class="col-md-4">
            <articles-form></articles-form>
        </div>
        <div class="col-md-4">
            <articles></articles>
        </div>

    </div>
</div>

I would like to automatically refresh the List Articles component every time a new article is created.

import { Component, OnInit } from '@angular/core';
import { ArticlesService } from '../../services/articles.service';
import { Article } from '../../models/article.model';
import { IArticles } from '../../interfaces/IArticles';
import { Observable } from 'rxjs';

@Component({
  selector: 'articles',
  templateUrl: './articles.component.html',
  styleUrls: ['./articles.component.css'],
  providers:[ArticlesService]
})
export class ArticlesComponent implements OnInit {

    ... // Code for fetching and displaying articles

}
<button class="btn btn-primary" (click)="fetchArticles()">
Reload Data
</button>
<div class="table table-responsive">
... // Table structure for displaying articles
</div>
import { Component, OnInit } from '@angular/core';
... // Import statements for ArticleForm related files

@Component({
  selector: 'articles-form',
  templateUrl: './articles-form.component.html',
  styleUrls: ['./articles-form.component.css'],
  providers:[ArticlesService]
})
export class ArticlesFormComponent implements OnInit {

    ... // Code for handling form submission to create an article

}

<div class="panel panel-primary">
... // Form structure for submitting new articles
</div>

To ensure real-time updates, I plan to refresh the List Articles component upon creating a new article.

Answer №1

Possible Solution:-

AppComponent.html(Parent)

<create-post  [data]="createPostData"></create-post>
<list-post [data]="listPostData"></list-post>

AppComponent.ts(Parent)

createPostData = "{"key":"value"}"
listPostData= "{"key":"value"}"

create-post.component.ts

@Input data;

list-post.component.ts

@Input data;

Calling a function:-

Using type selector

@Component({
  selector: 'child-cmp',
  template: '<p>child</p>'
})
class ChildCmp {
  doSomething() {}
}
@Component({
  selector: 'some-cmp',
  template: '<child-cmp></child-cmp>',
  directives: [ChildCmp]
})
class SomeCmp {
  @ViewChild(ChildCmp) child:ChildCmp;
  ngAfterViewInit() {
    // child is set
    this.child.doSomething();
  }
}

Using string selector

@Component({
  selector: 'child-cmp',
  template: '<p>child</p>'
})
class ChildCmp {
  doSomething() {}
}
@Component({
  selector: 'some-cmp',
  template: '<child-cmp #child></child-cmp>',
  directives: [ChildCmp]
})
class SomeCmp {
  @ViewChild('child') child:ChildCmp;
  ngAfterViewInit() {
    // child is set
    this.child.doSomething();
  }
}

Answer №2

There are various methods to accomplish a task.

You have 3 main components:

  1. HomeComponent - includes child components ArticlesFormComponent & ArticlesComponent
  2. ArticlesFormComponent - Used for creating new articles.
  3. ArticlesComponent - Displays and lists all existing articles.

The concept here is that you are already fetching a list of articles in the ArticlesComponent and most likely storing them in an array such as articlesArray. When a new article is created in the ArticlesFormComponent, an HTTP request is triggered. Upon receiving a successful response, the new article can be added to the existing articlesArray, updating the content in the ArticlesComponent automatically.

You currently have an ArticlesService handling HTTP requests. However, since the service is provided at the component level, it results in different instances. It would be more efficient to provide the ArticlesService at the module level to ensure a single instance for the entire application.

@NgModule({
    ...
    providers:[
         ...,
         ArticlesService
    ]
})
export class AppModule { }

Answer №3

There are various ways to communicate with components.

One approach is to create a service that emits events from child to parent using a subject. This allows you to subscribe to the data anywhere in the application and have it automatically update.

Here's an example snippet demonstrating this:

<div class="container">
    <div class="row>
        <div class="col-md-4">
            <app-articles-form></app-articles-form>
        </div>
        <div class="col-md-4">
            <app-articles></app-articles>
        </div>

    </div>
</div>

For more details, you can check out the following example: https://stackblitz.com/edit/angular-jncwsq

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