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

101 lines
3.1 KiB
TypeScript

import { Injectable } from '@angular/core';
import { Hero } from './hero';
import { Observable, of } from 'rxjs';
import { MessageService } from './message.service';
import { HttpClient, HttpHeaders } from '@angular/common/http';
import { catchError, map, tap } from 'rxjs/operators';
@Injectable({
providedIn: 'root'
})
export class HeroService {
httpOptions = {
headers: new HttpHeaders({ 'Content-Type': 'application/json' })
};
constructor(
private http: HttpClient,
private messageService: MessageService) { }
/** Log a HeroService message with the MessageService */
private log(message: string) {
this.messageService.add(`HeroService: ${message}`)
}
private heroesUrl = 'api/heroes'; // URL to web api
getHeroes(): Observable<Hero[]> {
return this.http.get<Hero[]>(this.heroesUrl)
.pipe(
catchError(this.handleError<Hero[]>('getHeroes', []))
);
}
/** GET hero by id. Will 404 if id not found */
getHero(id: number): Observable<Hero> {
const url = `${this.heroesUrl}/${id}`;
return this.http.get<Hero>(url).pipe(
tap(_ => this.log(`fetched hero id=${id}`)),
catchError(this.handleError<Hero>(`getHero id=${id}`))
);
}
/** PUT: update the hero on the server */
updateHero (hero: Hero): Observable<any> {
return this.http.put(this.heroesUrl, hero, this.httpOptions).pipe(
tap(_ => this.log(`updated hero id=${hero.id}`)),
catchError(this.handleError<any>('updateHero'))
);
}
addHero (hero: Hero): Observable<Hero> {
return this.http.post<Hero>(this.heroesUrl, hero, this.httpOptions).pipe(
tap((newHero: Hero) => this.log(`added hero w/ id=${newHero.id}`)),
catchError(this.handleError<Hero>('addHero'))
);
}
/** DELETE: delete the hero from the server */
deleteHero (hero: Hero | number): Observable<Hero> {
const id = typeof hero === 'number' ? hero : hero.id;
const url = `${this.heroesUrl}/${id}`;
return this.http.delete<Hero>(url, this.httpOptions).pipe(
tap(_ => this.log(`deleted hero id=${id}`)),
catchError(this.handleError<Hero>(`deleteHero id=${id}`))
);
}
searchHeroes(term: string): Observable<Hero[]> {
if (!term.trim()) {
// if not search term, return empty hero array.
return of([]);
}
return this.http.get<Hero[]>(`${this.heroesUrl}/?name=${term}`).pipe(
tap(_ => this.log(`found heroes matching "${term}"`)),
catchError(this.handleError<Hero[]>('searchHeroes', []))
);
}
/**
* Handle Http operation that failed.
* Let the app continue.
* @param operation - name of the operation that failed
* @param result - optional value to return as the observable result
*/
private handleError<T> (operation = 'operation', result?: T) {
return (error: any): Observable<T> => {
// TODO: send the error to remote logging infrastructure
console.error(error); // log to console instead
// TODO: better job of transforming error for user consumption
this.log(`${operation} failed: ${error.message}`);
// Let the app keep running by returning an empty result.
return of(result as T);
};
}
}