相关疑难解决方法(0)

我在Angular中遇到HTTP问题.

我只想要GET一个JSON列表并在视图中显示它.

服务类

import {Injectable} from "angular2/core";
import {Hall} from "./hall";
import {Http} from "angular2/http";
@Injectable()
export class HallService {
    public http:Http;
    public static PATH:string = 'app/backend/'    

    constructor(http:Http) {
        this.http=http;
    }

    getHalls() {
           return this.http.get(HallService.PATH + 'hall.json').map((res:Response) => res.json());
    }
}

在HallListComponent我getHalls从服务中调用方法:

export class HallListComponent implements OnInit {
    public halls:Hall[];
    public _selectedId:number;

    constructor(private _router:Router,
                private _routeParams:RouteParams,
                private _service:HallService) {
        this._selectedId = +_routeParams.get('id');
    }

    ngOnInit() {
        this._service.getHalls().subscribe((halls:Hall[])=>{ 
            this.halls=halls;
        });
    }
}

但是,我有一个例外:

TypeError:this.http.get(...).map不是[null]中的函数 …

我试图在我的代码中使用以下服务:

import {Injectable} from '@angular/core';
import {Http,Response} from "@angular/http";
import 'rxjs/Rx';

@Injectable()
export class HttpService{
    constructor(private http : Http){}

    getData(){
      return  this.http.get("URI")
      .map( (res: Response) => res.json()  );
    }
}

问题是,在运行时它抱怨:

res.json is not a function

我已将res的数据类型定义为Response,但仍然抱怨

.map( (res: Response) => res.json()  ) 

如果我用订阅替换地图它工作正常:

.subscribe( res =>{
                res.json();
                console.log("City is:"+ res.json().city.name)
            });