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:
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?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
}
}
}
最佳答案
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)。
关于javascript - 使用 typescript 作为自定义数据类型在 Angular 中返回 Promise,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/44620279/