Ionic 3和Ngzone()不起作用

Question

我想在蓝牙连接完成后执行一些操作,反之亦然.
处理连接的方案,并添加成功和失败处理程序,并在这些处理程序函数中将标志更改为True和False.
我使用console.log打印了该值,它在组件文件中更改但未反映在HTML中.
我尝试过使用ngZone,但它没有用.
成功和失败处理代码如下:

BluetoothService

import { Injectable } from "@angular/core";
import { BLE } from '@ionic-native/ble';


@Injectable()
export class BlueToothService {

    constructor(private ble: BLE){
    }

     public connect = (deviceId, onConnect, onFailure) => {
        this.ble.isConnected(deviceId)
            .then(response => {                   
                onConnect(response);
            },
            error =>  {
                this.ble.connect(deviceId)
                    .subscribe(response => {
                        onConnect(response);
                    },
                    error =>  {
                        onFailure(error);         
                    });            
        });
    } }

组件文件

import {Component, NgZone} from '@angular/core';
import {Events, IonicPage, NavController, NavParams, ViewController} from 'ionic-angular';

import {BlueToothService} from '../../../providers/bluetooth/bluetooth.service';

@IonicPage()
@Component({
    selector: 'test-data',
    templateUrl: 'test-data.html',
})
export class AddTestKitDataPage {
    public isBluetoothConnected: boolean = false;
    public deviceId: any;

    public connectToBLE() {
        this.blueToothService.connect(this.deviceId, onConnectionSuccess, onConnectionFailure);  //Assume device id is already present
    }

    private onConnectionSuccess = (reason) => {
        this.zone.run(() => {
            this.isBluetoothConnected = true;       
        });
    };

    private onConnectionFailure = (reason) => {
        this.zone.run(() => {
            this.isBluetoothConnected = false;
        });
    } }

HTML

<ion-content>

    <div text-center *ngIf="!isBluetoothConnected">
        Bluetooth Connection failure
    </div>

    <div text-center *ngIf="isBluetoothConnected">
        Bluetooth Connection success
    </div>

    <button ion-button full class="primaryBlockButton" (click)="connectToBLE()">Click</button>

</ion-content>

Answer 1

由于 console.log 确实确认在您的情况下数据确实发生了变化，而视图（模板）没有得到更新 - 这暗示未发生更改检测。

为了验证您是否已经尝试过“黑客”，并且根据您在评论中的说法，它有效：

private onConnectionSuccess = (reason) => { 
    this.zone.run(() => { 
        setTimeout(() => { 
            this.isBluetoothConnected = true; 
            console.log("isBluetoothConnected---", this.isBluetoothConnected); 
        },0) 
     }); 
};

基本上，黑客将你的数据更改“包装”为 Angular 拾取的异步（setTimeout）活动。

现在要解决这个问题，您可以确保您的案例中的数据更改通过 Angular 自然拾取的事件发生（例如添加自定义事件侦听器）。

或者尝试在数据更改后使用更改检测手动检测更改：

导入话单：

import { ChangeDetectorRef } from '@angular/core';

注入它：

constructor (private cdr: ChangeDetectorRef) {}

将其添加到您的方法中：

private onConnectionSuccess = (reason) => { 
    this.isBluetoothConnected = true; 
    console.log("isBluetoothConnected---", this.isBluetoothConnected);
    this.cdr.detectChanges();
};

尝试这种方法，因为我认为它会比 hack 更好。