服务 `http` get 方法没有 return 成功或错误

Question

我正在编写 return 一系列汽车的服务。我的服务方法没有 return 成功或错误。文件夹 assets 与 `app 文件夹位于同一目录中。

这是我的服务方式：

import {Injectable} from '@angular/core';
import {Http, Response} from '@angular/http';
import {Car} from '../../../domain/car';
import 'rxjs/add/operator/toPromise';

@Injectable()
export class CarService {

  constructor(private http: Http) {
  }
    getCarsMedium(): Promise<Car[]> {
       console.log("call1");
       return this.http.get('assets/data/cars-medium.json')
       .toPromise()
       .then(res => {
          console.log("sucess1" + res);
          console.log("sucess2" + res.json());
          return res.json().data as Car[]
          })
       .catch(error => {
          console.log("error");
          console.error(error);
       });
   }

}

我称之为：

import {Component, OnInit} from '@angular/core';
import {Car} from "../../../domain/car";
import {CarService} from "./car.service";

@Component({
  moduleId: module.id,
  templateUrl: './car.component.html',
  styleUrls: ['./car.component.css']
})

export class CarComponent implements OnInit {
  cars: Car[];

  constructor(private carService: CarService) {
  }

  ngOnInit() {
    console.log("call2");
    this.carService.getCarsMedium().then(function (cars) {
      cars => this.cars = cars;
      console.log(cars)
    });
  }
}

这是我的 json 的样子：

{"data":[
    {"vin":"a1653d4d","year":1998, "brand":"VW","color":"White"},
    {"vin":"a1653d4w","year":1999, "brand":"VV","color":"White"}
]}

实体class:

export interface Car {
  vin?;
  year?;
  brand?;
  color?;
}

编辑： getCarsMedium() 没有 return 成功或错误。控制台输出：通话2 call1

Answer 1

return this.http.get('assets/data/cars-medium.json') 
    .toPromise() 
    .then(res => res.json().data as Car[], 
          res => console.log(res));

显然，这不会打印任何内容，因为您正在打印传递给 then() 的第二个回调的响应，在承诺被拒绝（事实并非如此）的情况下执行。

改为这样做：

return this.http.get('assets/data/cars-medium.json') 
    .toPromise() 
    .then(res => {
        console.log(res);
        console.log(res.json());
        return res.json().data as Car[]
    });

Answer 2

找到原因了：项目中有jwt-authentication http://jasonwatmore.com/post/2016/08/16/angular-2-jwt-authentication-example-tutorial][1] - 它阻止了我的请求

服务 `http` get 方法没有 return 成功或错误

Service `http` get method doesn't return success or error

typescript

angular2-services

angular