angular2无法使用路由器导航

Question

I am trying to navigate to another route after users click a login button. But I can't understand what went wrong. Below is my login component.

 import { Component, OnInit } from '@angular/core'; import { AngularFire, AuthProviders, AuthMethods } from 'angularfire2'; import { Router, ActivatedRoute } from '@angular/router'; @Component({ selector: 'app-login', templateUrl: './login.component.html', styleUrls: ['./login.component.css'] }) export class LoginComponent implements OnInit { constructor(public af: AngularFire, private router: Router) { this.af.auth.subscribe(auth => console.log(auth)); } login() { this.af.auth.login({ provider: AuthProviders.Google, method: AuthMethods.Popup, }).then(function(res) { console.log('login success'); console.log(res.uid); this.router.navigateByUrl('/main') // .then(r => console.log('then: ' + r)) .then(function(resw) { console.log('has redirect'); }) .catch(err => console.error(err)) ; console.log('afterward'); }).catch(err => console.error(err)); } overrideLogin() { this.af.auth.login({ provider: AuthProviders.Anonymous, method: AuthMethods.Anonymous, }); } ngOnInit() { } } 

 <p> login works! </p> <button (click)="login()">Login With Google</button> <button (click)="overrideLogin()">Login Anonymously</button> 

Here is my routes:

import { LoginComponent } from './login/login.component';
import { MainComponent } from './main/main.component';
import { ModuleWithProviders }  from '@angular/core';
import { Routes, RouterModule } from '@angular/router' ;

const APP_ROUTES: Routes = [
    { path: 'login', component: LoginComponent },
    { path: '', pathMatch: 'full', redirectTo: '/login'},
    { path: 'main', component: MainComponent }
];

export const appRoutingProviders: any[] = [

];

export const APP_ROUTES_PROVIDER: ModuleWithProviders = RouterModule.forRoot(APP_ROUTES);

Here is the @NgModule:

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { HttpModule } from '@angular/http';

import { AppComponent } from './app.component';

// import routing
import { appRoutingProviders, APP_ROUTES_PROVIDER } from './app.routes' ;



@NgModule({
  declarations: [
    AppComponent,
    LoginComponent,
    MainComponent
  ],
  imports: [
    BrowserModule,
    // AngularFireModule.initializeApp(firebaseConfig, myFirebaseAuthConfig), // angularfire setup 
    FormsModule,
    HttpModule,
    APP_ROUTES_PROVIDER
  ],
  providers: [appRoutingProviders],
  bootstrap: [AppComponent]
})
export class AppModule { }

I got the following error. Can someone please help let me know how to fix this?

TypeError: this is null Stack trace: LoginComponent</LoginComponent.prototype.login/<@http://localhost:4200/main.bundle.js:70294:13 Zone$1</ZoneDelegate</ZoneDelegate.prototype.invoke@http://localhost:4200/main.bundle.js:69125:19 NgZoneImpl/this.inner<.onInvoke@http://localhost:4200/main.bundle.js:56178:28 Zone$1</ZoneDelegate</ZoneDelegate.prototype.invoke@http://localhost:4200/main.bundle.js:69124:19 Zone$1</Zone</Zone.prototype.run@http://localhost:4200/main.bundle.js:69018:24 scheduleResolveOrReject/<@http://localhost:4200/main.bundle.js:69384:52 Zone$1</ZoneDelegate</ZoneDelegate.prototype.invokeTask@http://localhost:4200/main.bundle.js:69158:23 NgZoneImpl/this.inner<.onInvokeTask@http://localhost:4200/main.bundle.js:56169:28 Zone$1</ZoneDelegate</ZoneDelegate.prototype.invokeTask@http://localhost:4200/main.bundle.js:69157:23 Zone$1</Zone</Zone.prototype.runTask@http://localhost:4200/main.bundle.js:69058:28 drainMicroTaskQueue@http://localhost:4200/main.bundle.js:69290:25 ZoneTask/this.invoke@http://localhost:4200/main.bundle.js:69230:25

Answer 1

Arrow Function(()=>) will resolve issue as every configuration is correct.

login() {
    this.af.auth.login({
      provider: AuthProviders.Google,
      method: AuthMethods.Popup,
    }).then((res)=> {                    //<----changed this line
       console.log('login success');
       console.log(res.uid);
       this.router.navigateByUrl('/main') // .then(r => console.log('then: ' + r))
      .then((resw)=> {                  //<----changed this line
         console.log('has redirect');
       })
       .catch(err => console.error(err)) ;
       console.log('afterward');
    }).catch(err => console.error(err));
  }

Answer 2

this is special in javascript, it depends how the function was called see How to access the correct `this` context inside a callback? .

In type script if you use a fat arrow => it'll cache the this for you eg this.af.auth.login({}).then((res) => {})