使用Angular 2 Http从REST Web服务获取数据

Question

我试图使用Angular 2 HTTP从REST web服务获取数据。

我首先将服务注入调用它的客户端组件类的构造函数中：

constructor (private _myService: MyService,
             private route: ActivatedRoute,
             private router: Router) {}

getData(myArg: string) {
    this._myService.fetchData(myArg)
      .subscribe(data => this.jsonData = JSON.stringify(data),
        error => alert(error),
        () => console.log("Finished")
      );

    console.log('response ' + this.jsonData);

this.getData(this.myArg);

import { Injectable } from '@angular/core';
    import { Http, Response } from '@angular/http';
    import 'rxjs/add/operator/map';

    @Injectable()
    export class MyService {
        constructor (private _http: Http) {}

        fetchData(myArg: string) {
            return this._http.get("http://date.jsontest.com/").map(res => res.json());
        }
    }

ps：jsonData是客户端组件类的字符串属性。

Answer 1

由于http请求是异步的，所以this.jsondata在尝试将其记录到控制台时不会设置。相反，将该日志放入subscribe回调：

getData(myArg: string){     
    this._myService.fetchData(myArg)
             .subscribe(data => { 
                            this.jsonData = JSON.stringify(data)
                            console.log(this.jsonData);
                        },
                        error => alert(error),
                        () => console.log("Finished")
    );
}