Angular2-TypeError:this.http.get(...).toPromise不是一个函数 [英] Angular2 - TypeError: this.http.get(...).toPromise is not a function

问题描述

我尝试遵循有关angular.io的教程(游览英雄) 但是，我没有使用教程，而是尝试在某些JSON上进行真正的GET请求.

i try to follow tutorial on angular.io (Tour the Heroes) But instead of tutorial I try to make real GET request on some JSON.

我的代码如下:

  private userUrl = 'https://jsonplaceholder.typicode.com/users';
  constructor(private http: Http) {}

  getUsersHttp(): Promise<User[]> {
    return this.http.get(this.userUrl)
      .toPromise()
      .then(response => response.json().data as User[])
      .catch(this.handleError);
  }

要提供服务，我仅导入一些基本内容:

To service I import just few basic things:

import { Injectable }     from '@angular/core';
import { Headers, Http, Response } from '@angular/http';
import { User } from './user';

user.ts基本上是TOH中heroe.ts的副本，所以:

Where user.ts is basicly copy of heroe.ts in TOH so:

export class User {
  id: number;
  name: string;
}

我如何在服务中调用此特定方法: 首先，我尝试多种方法，但在调试时，我尝试仅使用console.log记录它:

How I call this specific method in service: First I try multiple things but while debugging i try just console.log it so:

 console.log(this.userService.getUsersHttp());

在控制台中加载页面时，我发现了多个错误: 第一个是:

When page is loading in console i found multiple errors: First one is:

例外:TypeError:this.http.get(...).toPromise不是函数

EXCEPTION: TypeError: this.http.get(...).toPromise is not a function

第二个是:

例外:TypeError:this.http.get(...).toPromise不是 functionBrowserDomAdapter.logError @

EXCEPTION: TypeError: this.http.get(...).toPromise is not a functionBrowserDomAdapter.logError @

服务本身看起来不错.我在这一行中将服务添加到了app.module.ts:

Service it self looks fine. I added my service to app.module.ts in this line:

providers: [ HTTP_PROVIDERS, UserService ]

，如果我直接使用某些函数返回数据(并注释掉调用getUsertHttp函数)，则可以使用它:

and it works if I directly return data with some function like (and comment out calling getUsertHttp function):

  getUsers() {
    return [{'id': 1, 'name': 'User1'}, {'id': 2, 'name': 'User2'}];
  }

我尝试描述所有可能很重要的内容，如果问题有点长时间，请抱歉. 伙计们，您能给我提示我做错了什么吗?

I try to describe everything which may be important so sorry if question is kind long a bit. Please guys can you give me hint what i am doing wrong?

推荐答案

好像您缺少导入:

import 'rxjs/add/operator/toPromise';

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