從 Angular2 中的 Restful API 讀取

為了將 API 邏輯與元件分開，我們將 API 客戶端建立為單獨的類。此示例類向 Wikipedia API 發出請求以獲取隨機 Wiki 文章。

    import { Http, Response } from '@angular/http';
    import { Injectable } from '@angular/core';
    import { Observable }     from 'rxjs/Observable';
    import 'rxjs/Rx';
    
    @Injectable()
    export class WikipediaService{
        constructor(private http: Http) {}
    
        getRandomArticles(numberOfArticles: number)
        {
            var request = this.http.get("https://en.wikipedia.org/w/api.php?action=query&list=random&format=json&rnlimit=" + numberOfArticles);
            return request.map((response: Response) => {
                return response.json();
            },(error) => {
                console.log(error);
                //your want to implement your own error handling here.
            });
        }
    }

並有一個元件來使用我們的新 API 客戶端。

import { Component, OnInit } from '@angular/core';
import { WikipediaService } from './wikipedia.Service';

@Component({
    selector: 'wikipedia',
    templateUrl: 'wikipedia.component.html'
})
export class WikipediaComponent implements OnInit {
    constructor(private wikiService: WikipediaService) { }

    private articles: any[] = null;
    ngOnInit() { 
        var request = this.wikiService.getRandomArticles(5);
        request.subscribe((res) => {
            this.articles = res.query.random;
        });
    }
}