javascript - 使用 typescript 作为自定义数据类型在 Angular 中返回 Promise

Question

我是 Typescript 的新手，我正在尝试返回类型为 Device 的对象的 promise ，但我无法访问它。

问题是当我返回一个 Mock 时一切正常，但是当我连接到一个真正的 API 时我在这里遇到问题 response.json().data as Device。

当我在服务器中请求数据，然后我尝试在模板中打印它时，一切都消失了，在控制台中我有 Undefined。函数 getDevices() 中 device.component.ts 中的 console.log 也像对象的旧状态一样打印，因为当我更改数据时，会出现之前应该显示的数据。

我有几个问题，例如:

1. 我如何访问 promise 的 .then 中的 response.json().data 以查看其结构或数据是什么它有？

2. 我如何映射(我认为这个术语对于 Observable 是正确的，但我不知道如何为 Promise 说)我的 device 对象与 API 的数据 ?

device.component.ts

import { Component, OnInit, Input } from '@angular/core';
import { Device } from './device';
import { DeviceService } from './device.service';

@Component({
selector: 'app-device',
templateUrl: './device.component.html'
})

export class DeviceComponent implements OnInit {
    @Input() private device: Device;
    constructor(private deviceService: DeviceService) {};

    ngOnInit(): void {
        // this.getDevice(40072);
        this.deviceService.getDeviceMock().then(device => this.device = device);
    }

    getDevice(id: number): void {
        this.deviceService.getDevice(id).then(device => this.device = device);
        console.log(this.device);
        // this.deviceService.getDeviceMock().then(device => this.device = device);
    }

    search(id: number): void {
        this.getDevice(id);
}

    save(): void {
        this.deviceService.setDevice(this.device);
    }
}

device.component.html

<input [(ngModel)]="idSearch" type="text" placeholder="Insert ID"  >
<button (click)="search(idSearch)">Search</button>

<div *ngIf="device">
<div>
  <label>Uid: </label>
  <input [(ngModel)]="device.Uid" placeholder="Uid">
</div>

<div>
  <label>VigilId: </label>
<input [(ngModel)]="device.VigilId" placeholder="VigilId">
</div>

<div>
  <label>CmfPhoneNumber: </label>
  <input [(ngModel)]="device.Model.RuntimeSettings.CmfPhoneNumber" placeholder="CmfPhoneNumber">
</div>

<div>
  <label>ReportInterval: </label>
  <input [(ngModel)]="device.Model.RuntimeSettings.ReportInterval" placeholder="ReportInterval">
</div>

<div>
  <label>GeoLocationHighAccuracy: </label>
  <input [(ngModel)]="device.Model.RuntimeSettings.GeoLocationHighAccuracy" placeholder="GeoLocationHighAccuracy">
</div>

<div>
  <label>AlarmCancelTimeout: </label>
  <input [(ngModel)]="device.Model.RuntimeSettings.AlarmCancelTimeout" placeholder="AlarmCancelTimeout">
</div>

<div>
  <label>AdherenceCheckInterval: </label>
  <input [(ngModel)]="device.Model.RuntimeSettings.AdherenceCheckInterval" placeholder="AdherenceCheckInterval">
</div>

<div>
  <label>PreAlarmPeriod: </label>
  <input [(ngModel)]="device.Model.RuntimeSettings.PreAlarmPeriod" placeholder="PreAlarmPeriod">
</div>

<div>
  <label>PingInterval: </label>
  <input [(ngModel)]="device.Model.RuntimeSettings.PingInterval" placeholder="PingInterval">
</div>

<button (click)="save()">Send</button>

device.service.ts

import { Component } from '@angular/core';
import { Device } from './device';
import { Injectable } from '@angular/core';
import { Headers, Http } from '@angular/http';
import 'rxjs/add/operator/toPromise';

import { DeviceMock } from './device-mock'


@Injectable()
export class DeviceService {
    // TODO: Create configuration file.
    private apiUrl = 'https://api.com/api2/v2';
    private headers = new Headers({'Authorization': 'xxxx'});

    constructor(private http: Http) {};
    getDeviceMock(): Promise<Device> {
        return Promise.resolve(DeviceMock)
    }

    getDevice(id: number): Promise<Device> {
        const url = `${this.apiUrl}/device/${id}?names=RuntimeSettings`;
        return this.http.get(url, {headers: this.headers})
            .toPromise()
            .then(response => response.json().data as Device)
            .catch(this.handleError);
    }

    setDevice(device: Device): Promise<Device> {
        this.headers.set('Content-Type', 'application/json');
        const url = `${this.apiUrl}/device/${device.VigilId}?names=RuntimeSettings`;
        return this.http.put(url, JSON.stringify(device), {headers: this.headers})
            .toPromise()
            .then(response => response.json().data as Device)
            .catch(this.handleError);
    }

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

device.ts

export interface Device {
    VigilId: number;
    Uid: string;
    Model: Model;
};

interface Model {
    RuntimeSettings: RuntimeSettings;
};

interface RuntimeSettings {
    ReportInterval: number;
    PingInterval: number;
    PreAlarmPeriod: number;
    AdherenceCheckInterval: number;
    AlarmClearTimeout: number;
    AlarmCancelTimeout: number;
    DailyReportInterval: number;
    GeoLocationRetryCount: number;
    GeoLocationHighAccuracy: true;
    GeoLocationTimeOut: number;
    GeoMaxAgeTimeOut: number;
    CmfPhoneNumber: number;
    PalmTouchTrigger: boolean;
    TouchTriggerCooldownPeriod: number;
    DemoMode: boolean;
    DeviceName: string;
    VerboseLogging: boolean;
};

这是API的响应

{
    "VigilId": 41,
    "Uid": "Identi",
    "Model": {
        "RuntimeSettings": {
            "ReportInterval": 900,
            "PingInterval": 300,
            "PreAlarmPeriod": 10,
            "AdherenceCheckInterval": 3600,
            "AlarmClearTimeout": 600,
            "AlarmCancelTimeout": 15,
            "DailyReportInterval": 43200,
            "GeoLocationRetryCount": 3,
            "GeoLocationHighAccuracy": true,
            "GeoLocationTimeOut": 5000,
            "GeoMaxAgeTimeOut": 60,
            "CmfPhoneNumber": "",
            "PalmTouchTrigger": true,
            "TouchTriggerCooldownPeriod": 30,
            "DemoMode": false,
            "DeviceName": "",
            "VerboseLogging": false
        }
    }
}

Answer 1

对于问题(1):

您必须注意到 HTTP 客户端请求是异步的。这意味着外部/父函数不会等待网络请求完成，即不会阻塞。这就是您在 getDevices 上获得“旧数据”的原因:它会在从服务器响应更新对象之前打印该对象。

getDevice(id: number): void {
    this.deviceService.getDevice(id)
        .then(device => this.device = device);  // network request is scheduled
    console.log(this.device); // device is printed to log but not necessarily
                              // after the network request returns
}

要解决它，将其更改为:

getDevice(id: number): void {
    this.deviceService.getDevice(id).then(device => {
        console.log(device); // print to console what is returned from network
        this.device = device;
    });
}

对于问题(2):

你正在做的 this.device = device 是正确的，这将更新你的 this.device 对象并将它指向新的 device 来自服务器响应的对象。 (除非我错误地理解了这个问题)。