Get hash url parameters to redirect to requesting url when using Auth0 with Angular 2
<p>Auth0 requires you to whitelist callback URLs after authentication so you can't just login on any page in your application with URLs like /thing/1, /thing/1001 as there's no way to wildcard the thing IDs.</p>

<p>This <a href="https://github.com/auth0/wp-auth0/issues/29#issuecomment-252040395" rel="nofollow noreferrer">Github conversation</a> points to neat solution which I have interpreted in Angular 2 as:</p>

<p>In my auth.service.ts:</p>

<pre><code>lock = new Auth0Lock('Client_ID', 'Domain', {
        auth: {
            redirectUrl: window.location.origin + '/login',
            responseType: 'token',
            params: {
                scope: 'openid name email',
                state: JSON.stringify({pathname: window.location.pathname})
            }
        }
    });
</code></pre>

<p>I can then whitelist my /login route in Angular 2. I tried getting my login.component.ts to read and then navigate to the pathname returned by Auth0 in the call back like this:</p>

<pre><code>this.route
    .queryParams
    .subscribe(params =&gt; {
         this.state = params['state'];
         this.router.navigate(this.state, {preserveQueryParams: true});
     });
</code></pre>

<p>...but params always seems to be empty. As far as I can tell this is because the call back URL is of this form:</p>

<p><a href="http://localhost:5555/login#access_token=...&amp;id_token=...&amp;token_type=Bearer&amp;state=%7B%22pathname%22%3A%22%2Flogin%22%7D" rel="nofollow noreferrer">http://localhost:5555/login#access_token=...&amp;id_token=...&amp;token_type=Bearer&amp;state=%7B%22pathname%22%3A%22%2Flogin%22%7D</a></p>

<p>...and Angular 2 routing automatically strips off the # parameters before they get to the LoginComponent.</p>

<p>I then spotted that authResult on lock.authenticated still contains my state parameter in auth.service.ts so attempted to navigate to it as follows:</p>

<pre><code>this.lock.on("authenticated", (authResult:any) =&gt; {
    localStorage.setItem('id_token', authResult.idToken);
    let state: string = JSON.parse(authResult.state);
    this.router.navigate([state.pathname], {});
</code></pre>

<p>This seemed to work initially but, it turns out, not reliably...it seems to redirect me unpredictably anywhere from </p>

<pre><code>/thing/1001 to 
/things or even 
/
</code></pre>

<p>...and I can't work out why. Any help very much appreciated.</p>

<p><strong>EDIT In response to @shusson's answer:</strong></p>

<p>Working code based on @shusson's answer is in auth.service.ts:</p>

<pre><code>export class Auth {
    // Configure Auth0
    lock = new Auth0Lock('Client_ID', 'Domain',{
        auth: {
            redirectUrl: location.origin + '/login',
            responseType: 'token',
        }
    });

    constructor(private router: Router, route: ActivatedRoute) {

        // Add callback for lock `authenticated` event
        this.lock.on("authenticated", (authResult:any) =&gt; {
            localStorage.setItem('id_token', authResult.idToken);
            let state: any = JSON.parse(authResult.state);
            this.router.navigate([state.pathname], {});
        ...
     }

    public login() {
        // Call the show method to display the widget.
        this.lock.show({
            auth: {
                params: {
                    scope: 'openid name email',
                    state: JSON.stringify({pathname: this.router.url})
                }
            }
        });
    };
</code></pre>

<p><strong>EDIT: based on <a href="https://auth0.com/forum/t/redirect-with-call-back-hash-url-parameters-angular-2/4420/2?u=theotherdy" rel="nofollow noreferrer">this comment</a> re: passing paths in callback being a CSRF vulnerability:</strong></p>

<p>Final working code in my auth.service.ts is:</p>

<pre><code>import { Injectable }      from '@angular/core';
import { tokenNotExpired } from 'angular2-jwt/angular2-jwt';
import { Router, ActivatedRoute } from '@angular/router';
import { UUID } from 'angular2-uuid/index';

// Avoid name not found warnings
declare var Auth0Lock: any;

@Injectable()
export class Auth {
    // Configure Auth0
    lock = new Auth0Lock('Client_ID', 'Domain',{
        auth: {
            redirectUrl: location.origin + '/login',
            responseType: 'token',
        }
    });
    //Store profile object in auth class
    userProfile: Object;

    constructor(private router: Router, route: ActivatedRoute) {

        // Set userProfile attribute of already saved profile
        this.userProfile = JSON.parse(localStorage.getItem('profile'));

        // Add callback for lock `authenticated` event
        this.lock.on("authenticated", (authResult:any) =&gt; {
            localStorage.setItem('id_token', authResult.idToken);
            let pathname_object: any = JSON.parse(authResult.state);
            let pathname: any = localStorage.getItem(pathname_object.pathname_key);
            //get rid of localStorage of url
            localStorage.removeItem(pathname_object.pathname_key);
            //navigate to original url
            this.router.navigate([pathname], {});

        // Fetch profile information
        this.lock.getProfile(authResult.idToken, (error:any, profile:any) =&gt; {
            if (error) {
                // Handle error
                alert(error);
                return;
            }

            localStorage.setItem('profile', JSON.stringify(profile));
                this.userProfile = profile;
            });
        });
    }

    public login() {
        //generate UUID against which to store path
        let uuid = UUID.UUID();
        localStorage.setItem(uuid, this.router.url);
        // Call the show method to display the widget.
        this.lock.show({
            auth: {
                params: {
                    scope: 'openid name email',
                    state: JSON.stringify({pathname_key: uuid})
                }
            }
        });
    };
...
}
</code></pre>