not working

tools/app/angular-tour-of-heroes/src/app/dashboard/dashboard.component.ts

@@ -17,7 +17,7 @@ export class DashboardComponent implements OnInit {
   }
 
   getHeroes(): void {
-    this.heroService.getHeroes().subscribe(heroes => this.heroes = heroes.slice(1, 5));
+    this.heroService.getHeroes().then(heroes => this.heroes = heroes.slice(1, 5));
   }
 
 }

tools/app/angular-tour-of-heroes/src/app/db-handle.ts

@@ -0,0 +1,28 @@
+import { Connection, ConnectionConfig, createConnection } from 'mariadb'
+
+export class DbHandle {
+    private connConfig?: ConnectionConfig
+    private conn?: Connection
+
+    public constructor() {
+        this.connConfig = {
+            host: '172.16.10.18',
+            user: 'heroes',
+            password: 'test123',
+            database: 'heroes'
+        }
+    }
+
+    public async connect(): Promise<void> {
+        this.conn = await createConnection(this.connConfig)
+    }
+
+    public query(stmt: string) : Promise<any> {
+        return this.conn?.query(stmt) ?? Promise.reject(new Error('Connection not ready (query)'))
+    }
+
+    public close() : Promise<void> {
+        return this.conn?.end() ?? Promise.reject(new Error('Connection not ready (close)'))
+    }
+
+}

tools/app/angular-tour-of-heroes/src/app/hero-detail/hero-detail.component.ts

@@ -22,7 +22,7 @@ export class HeroDetailComponent implements OnInit {
 
   getHero(): void {
     const id = +this.route.snapshot.paramMap.get('id');
-    this.heroService.getHero(id).subscribe(hero => this.hero = hero);
+    this.heroService.getHero(id).then(hero => this.hero = hero);
   }
 
   goBack(): void {
@@ -30,6 +30,6 @@ export class HeroDetailComponent implements OnInit {
   }
 
   save(): void {
-    this.heroService.updateHero(this.hero).subscribe(() => this.goBack());
+    this.heroService.updateHero(this.hero).then(() => this.goBack());
   }
 }

tools/app/angular-tour-of-heroes/src/app/hero.service.ts

@@ -1,5 +1,6 @@
 import { Injectable } from '@angular/core';
-import { Observable, of } from 'rxjs';
+
+import { DbHandle } from './db-handle';
 
 import { Hero } from './hero';
 import { HEROES } from './mock-heroes';
@@ -9,21 +10,36 @@ import { MessageService } from './message.service';
   providedIn: 'root'
 })
 export class HeroService {
-
   constructor(private messageService: MessageService) { }
 
-  getHeroes(): Observable<Hero[]> {
+  async getHeroes(): Promise<Hero[]> {
     this.messageService.add('HeroService: fetched heroes');
-    return of(HEROES);
+    const dbHandle = new DbHandle()
+    try {
+      await dbHandle.connect()
+      const result = await dbHandle.query('SELECT id, name FROM hero')
+      return result.map((row: Record<string, unknown>) => {
+        return {id: row.id ?? -1, name: row.name ?? 'unknown' }
+      })
+    } finally {
+      dbHandle.close()
+    }
   }
 
-  getHero(id: number): Observable<Hero> {
+  async getHero(id: number): Promise<Hero> {
     this.messageService.add(`HeroService: fetch hero id=${id}`);
-    return of(HEROES.find(hero => hero.id === id));
+    const dbHandle = new DbHandle()
+    try {
+      await dbHandle.connect()
+      const result = await dbHandle.query(`SELECT id, name FROM hero WHERE id = ${id}`)
+      return { id: result[0].id ?? -1, name: result[0].name ?? 'unknown' }
+    } finally {
+      dbHandle.close()
+    }
   }
 
-  updateHero(hero: Hero): Observable<any> {
+  updateHero(hero: Hero): Promise<any> {
     this.messageService.add(`HeroService: save change: id=${hero.id}, name=${hero.name}`);
-    return of(true);
+    return Promise.resolve(true);
   }
 }

tools/app/angular-tour-of-heroes/src/app/heroes/heroes.component.ts

@@ -19,7 +19,7 @@ export class HeroesComponent implements OnInit {
   constructor(private heroService: HeroService, private messageService: MessageService) { }
 
   getHeroes(): void {
-    this.heroService.getHeroes().subscribe(heroes => this.heroes = heroes);
+    this.heroService.getHeroes().then(heroes => this.heroes = heroes);
   }
 
   ngOnInit(): void {