类型Promise <void>不能分配给Promise <customType []>类型

Question

我是angularJs2的新手.我创建了以下服务:

import { Injectable, OnInit } from '@angular/core';
import { customType } from '../models/currentJobs';
import { Headers, Http } from '@angular/http';

import 'rxjs/add/operator/toPromise';

@Injectable()
export class JobService implements OnInit {

    constructor(private http: Http) { }

    ngOnInit(): void {
        this.getCurrentJobs();
    }

    private headers: Headers = new Headers({ 'Content-Type': 'application/json' });
    private ordersUrl: string = 'http://localhost:35032/api/order/';

    public orders: customType[];

    getCurrentJobs(): Promise<customType[]> {
        var jobs =  this.http.get(this.ordersUrl)
            .toPromise()
            .then(response => {
                this.orders = response.json() as customType[];
            })
            .catch(this.handleError);
        return jobs;//this line throws error
    }

    private handleError(error: any): Promise<any> {
        console.error('An error occurred', error);
        return Promise.reject(error.message || error);
    }
}

以下是Vs2017的Typescript编译配置

当我使用visual studio 2017编译代码时,我得到以下错误

**TS2322 Build:Type 'Promise<void>' is not assignable to type 'Promise<customType[]>'.**

帮我解决这个错误.

Answer 1

你是不是给您回里的任何东西then,这使得jobs具有类型Promise<void>.返回内部数组then:

getCurrentJobs(): Promise<customType[]> {
    var jobs = this.http.get(this.ordersUrl)
      .toPromise()
      .then(response => {
        this.orders = response.json() as customType[];
        return this.orders;
      })
      .catch(this.handleError);
    return jobs;
}

查看promises的链接行为:https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/then#Chaining