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我使用ionic2在新的應用程序，我想路由調用來自服務器的HTTP請求承諾函數內我的網頁，導航離子2
一個承諾函數裏面我要訪問的Navcontroller在promise函數內部，但Navcontroller不能從promise函數內部訪問。 承諾的功能是的AuthenticationService
內部功能的承諾，這是我的裏面app.component.ts代碼：
import {Component, ViewChild, Inject} from '@angular/core';
import {Platform, NavController} from 'ionic-angular';
import { StatusBar } from 'ionic-native';
import { HomePage } from '../pages/home/home';
import { LoginPage } from '../pages/login/login';
import {Authentication} from '../providers/authentication';
@Component({
template: `<ion-nav #myNav [root]="rootPage"></ion-nav>`,
providers:[Authentication],
})
export class MyApp {
@ViewChild('myNav') public nav : NavController
//rootPage = LoginPage;
constructor(platform: Platform, private auth:Authentication) {
platform.ready().then(() => {
StatusBar.styleDefault();
});
}
ngOnInit() {
this.auth.index()
.then(function (data) {
if(data['flag']==1)
{
this.nav.setRoot(HomePage);
}
else
{
this.nav.setRoot(LoginPage);
}
})
，這是錯誤：
EXCEPTION: Uncaught (in promise): TypeError: Cannot read property 'nav' of null
TypeError: Cannot read property 'nav' of null.