类型'Observable <Response>'上不存在属性'toPromise'

Question

import { Headers, Http } from '@angular/http';

@Injectable()
export class PublisherService{

    private publishersUrl = 'app/publisher';

    constructor(private http: Http) { }

    getPublishers(): Promise<Publisher[]>{
        return this.http.get(this.publishersUrl)
                   .toPromise()
                   .then(response => response.json().data) 
                   .catch(this.handleError);
    }
}    

I am getting this error:

Property 'toPromise' does not exist on type 'Observable'.any

Answer 1

You need to add the operator like this:

import 'rxjs/add/operator/toPromise';

This is needed for every rxjs operator you want to use.

Answer 2

Try adding 'Response' to your import statement from '@angular/http' like this :

import {Http, Headers, Response} from '@angular/http';

Also i noticed you don't import Ingectable from angular core although you use @Injectable decorator.

import { Injectable } from '@angular/core';

Answer 3

一开始就使用这个导入

import {Observable} from "rxjs/Rx";