角5 HTTP负载json文件错误

Question

newsService.ts

import { Injectable } from '@angular/core';
    import { HttpClient } from '@angular/common/http';
    import { INews } from './inews';
    import { Observable } from 'rxjs';
    import { map } from 'rxjs/operators';

    @Injectable({
      providedIn: 'root'
    })
    export class NewsserviceService {
      public _url = 'http://localhost/admin/demo/api/get_posts/';
      constructor( public http: HttpClient) { }
      getNews(): Observable<INews[]> {
        return this.http.get<INews[]>(this._url).pipe(map(res => res.json()));
      }
     }

newsComponent.ts

import { Component, OnInit } from '@angular/core';
import { NewsserviceService } from './newsservice.service';

@Component({
  selector: 'app-news-ticker',
  templateUrl: './news-ticker.component.html',
  styleUrls: ['./news-ticker.component.scss']
})
export class NewsTickerComponent implements OnInit {
  public news: any[];
  constructor(private newsservice: NewsserviceService) { }

  ngOnInit() {
    this.loadNews();
  }
  loadNews(): void {
    this.newsservice.getNews().subscribe(res => this.news = res);

  }

}

newscomponent.html

<section class="news-ticker">
  <div class="container">
    <div class="row">
      <div class="col-md-12">
        <div class="ticker">
          <strong class="pull-left">news flash</strong>
          <ul>
            <li *ngFor='let news of news'>
              {{news.content}}
            </li>
          </ul>
        </div>
      </div>
    </div>
  </div>
</section>

控制台错误

ERROR TypeError:在MapSubscriber.push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber.next (Subscriber.js:93)的MapSubscriber.project (newsservice.service.ts:14) at MapSubscriber.push../node_modules/rxjs/_esm5/internal/operators/map. (map.js:75)上，res.json不是一个函数。MapSubscriber.push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber.next (Subscriber.js:93)、FilterSubscriber.push../node_modules/rxjs/_esm5/internal/operators/filter.js.FilterSubscriber._next (filter.js:85)、FilterSubscriber.push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber.next (Subscriber.js:93)的js.MapSubscriber._next (map.js:81)MergeMapSubscriber.push../node_modules/rxjs/_esm5/internal/operators/mergeMap.js.MergeMapSubscriber.notifyNext (mergeMap.js:136) at InnerSubscriber.push../node_modules/rxjs/_esm5/internal/InnerSubscriber.js.InnerSubscriber._next (InnerSubscriber.js:20) at InnerSubscriber.push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber.next (Subscriber.js:93)

Answer 1

你最好写一些关于你的问题的信息，但是你的问题可以参考

 getNews(): Observable<INews[]> {
            return this.http.get<INews[]>(this._url).pipe(map(res => res.json()));
      }

在您的服务中，将其更改为：

   getNews():Observable {
        return this.http.get(this._url)
      }

由于该方法提供了可观察的功能，所以我们应该在目标组件中订阅它，您可以这样做：

loadNews() {
    this.newsservice.getNews().subscribe(res => this.news = res);

  }