Adding messages by message-service

Author: ronaldovctor

src/app/app.component.html

@@ -1,2 +1,3 @@
 <h1>{{ title }}</h1>
-<app-heroes></app-heroes>
+<app-heroes></app-heroes>
+<app-messages></app-messages>

src/app/app.module.ts

@@ -5,12 +5,14 @@ import { BrowserModule } from '@angular/platform-browser';
 import { AppComponent } from './app.component';
 import { HeroesComponent } from './heroes/heroes.component';
 import { HeroDetailComponent } from './hero-detail/hero-detail.component';
+import { MessagesComponent } from './messages/messages.component';
 
 @NgModule({
   declarations: [
     AppComponent,
     HeroesComponent,
-    HeroDetailComponent
+    HeroDetailComponent,
+    MessagesComponent
   ],
   imports: [
     BrowserModule,

src/app/hero.service.ts

@@ -2,17 +2,18 @@ import { Injectable } from '@angular/core';
 import { Observable, of } from 'rxjs';
 import { HEROES } from './data/mock-heroes';
 import { Hero } from './heroes/hero';
+import { MessageService } from './message.service';
 
 @Injectable({
   providedIn: 'root'
 })
 export class HeroService {
 
-  constructor() { }
+  constructor(private messageService: MessageService) { }
 
   getHeroes(): Observable<Hero[]> {
     const heroes = of(HEROES)
+    this.messageService.add('HeroService: fetched heroes')
     return heroes
-
   }
 }

src/app/heroes/heroes.component.ts

@@ -1,5 +1,6 @@
 import { Component, OnInit } from '@angular/core';
 import { HeroService } from '../hero.service';
+import { MessageService } from '../message.service';
 import { Hero } from './hero';
 
 @Component({
@@ -11,7 +12,7 @@ export class HeroesComponent implements OnInit {
   heroes?: Hero[] = []
   selectedHero?: Hero
 
-  constructor(private heroService: HeroService) { }
+  constructor(private heroService: HeroService, private messageService: MessageService) { }
 
   getHeroes(): void {
     this.heroService.getHeroes().subscribe(heroes => this.heroes = heroes)
@@ -23,5 +24,6 @@ export class HeroesComponent implements OnInit {
 
   onSelect(hero: Hero): void {
     this.selectedHero = hero
+    this.messageService.add(`HeroesComponent: Selected hero id=${hero.id}`)
   }
 }

src/app/message.service.spec.ts

@@ -0,0 +1,16 @@
+import { TestBed } from '@angular/core/testing';
+
+import { MessageService } from './message.service';
+
+describe('MessageService', () => {
+  let service: MessageService;
+
+  beforeEach(() => {
+    TestBed.configureTestingModule({});
+    service = TestBed.inject(MessageService);
+  });
+
+  it('should be created', () => {
+    expect(service).toBeTruthy();
+  });
+});

src/app/message.service.ts

@@ -0,0 +1,16 @@
+import { Injectable } from '@angular/core';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class MessageService {
+  messages: string[] = []
+
+  add(message: string): void {
+    this.messages.push(message)
+  }
+
+  clear(): void {
+    this.messages = []
+  }
+}

src/app/messages/messages.component.css

@@ -0,0 +1,7 @@
+<div *ngIf="messageService.messages.length">
+   <h2>Messages</h2>
+   <button type="button" class="clear" (click)="messageService.clear()">
+      Clear Message
+   </button>
+   <div *ngFor='let message of messageService.messages'> {{message}} </div>
+</div>

src/app/messages/messages.component.html

@@ -0,0 +1,25 @@
+import { ComponentFixture, TestBed } from '@angular/core/testing';
+
+import { MessagesComponent } from './messages.component';
+
+describe('MessagesComponent', () => {
+  let component: MessagesComponent;
+  let fixture: ComponentFixture<MessagesComponent>;
+
+  beforeEach(async () => {
+    await TestBed.configureTestingModule({
+      declarations: [ MessagesComponent ]
+    })
+    .compileComponents();
+  });
+
+  beforeEach(() => {
+    fixture = TestBed.createComponent(MessagesComponent);
+    component = fixture.componentInstance;
+    fixture.detectChanges();
+  });
+
+  it('should create', () => {
+    expect(component).toBeTruthy();
+  });
+});

src/app/messages/messages.component.spec.ts

@@ -0,0 +1,16 @@
+import { Component, OnInit } from '@angular/core';
+import { MessageService } from '../message.service';
+
+@Component({
+  selector: 'app-messages',
+  templateUrl: './messages.component.html',
+  styleUrls: ['./messages.component.css']
+})
+export class MessagesComponent implements OnInit {
+
+  constructor(public messageService: MessageService) { }
+
+  ngOnInit(): void {
+  }
+
+}