docs: fix redirect with secondary outlet in router guide example (#29267)

The URL wasn't be parsed into a UrlTree, so redirecting with a
secondary route went to a 404

Closes #28805

PR Close #29267

aio/content/examples/router/e2e/src/app.e2e-spec.ts

@@ -31,6 +31,7 @@ describe('Router', () => {
       heroDetailTitle: heroDetail.element(by.xpath('*[2]')),
 
       adminHref: hrefEles.get(2),
+      adminPage: element(by.css('app-root > div > app-admin')),
       adminPreloadList: element.all(by.css('app-root > div > app-admin > app-admin-dashboard > ul > li')),
 
       loginHref: hrefEles.get(3),
@@ -138,6 +139,31 @@ describe('Router', () => {
     expect(page.secondaryOutlet.count()).toBe(1, 'secondary outlet');
   });
 
+  it('should redirect with secondary route', async () => {
+    const page = getPageStruct();
+
+    // go to login page and login
+    await browser.get('');
+    await page.loginHref.click();
+    await page.loginButton.click();
+
+    // open secondary outlet
+    await page.contactHref.click();
+
+    // go to login page and logout
+    await page.loginHref.click();
+    await page.loginButton.click();
+
+    // attempt to go to admin page, redirects to login with secondary outlet open
+    await page.adminHref.click();
+
+    // login, get redirected back to admin with outlet still open
+    await page.loginButton.click();
+
+    expect(await page.adminPage.isDisplayed()).toBeTruthy();
+    expect(page.secondaryOutlet.count()).toBeTruthy();
+  });
+
   async function crisisCenterEdit(index: number, save: boolean) {
     const page = getPageStruct();
     await page.crisisHref.click();

aio/content/examples/router/src/app/auth/login/login.component.1.ts

@@ -27,10 +27,10 @@ export class LoginComponent {
       if (this.authService.isLoggedIn) {
         // Get the redirect URL from our auth service
         // If no redirect has been set, use the default
-        let redirect = this.authService.redirectUrl ? this.authService.redirectUrl : '/crisis-center/admin';
+        let redirect = this.authService.redirectUrl ? this.router.parseUrl(this.authService.redirectUrl) : '/admin';
 
         // Redirect the user
-        this.router.navigate([redirect]);
+        this.router.navigateByUrl(redirect);
       }
     });
   }

aio/content/examples/router/src/app/auth/login/login.component.ts

@@ -28,7 +28,7 @@ export class LoginComponent {
       if (this.authService.isLoggedIn) {
         // Get the redirect URL from our auth service
         // If no redirect has been set, use the default
-        let redirect = this.authService.redirectUrl ? this.authService.redirectUrl : '/admin';
+        let redirect = this.authService.redirectUrl ? this.router.parseUrl(this.authService.redirectUrl) : '/admin';
 
         // #docregion preserve
         // Set our navigation extras object
@@ -39,7 +39,7 @@ export class LoginComponent {
         };
 
         // Redirect the user
-        this.router.navigate([redirect], navigationExtras);
+        this.router.navigateByUrl(redirect, navigationExtras);
         // #enddocregion preserve
       }
     });

aio/content/guide/router.md

@@ -3849,7 +3849,7 @@ Update the `AuthGuard` to provide a `session_id` query that will remain after na
 
 Add an `anchor` element so you can jump to a certain point on the page.
 
-Add the `NavigationExtras` object to the `router.navigate` method that navigates you to the `/login` route.
+Add the `NavigationExtras` object to the `router.navigate()` method that navigates you to the `/login` route.
 
 
 <code-example path="router/src/app/auth/auth.guard.4.ts" linenums="false" header="src/app/auth/auth.guard.ts (v3)">
@@ -3860,7 +3860,7 @@ Add the `NavigationExtras` object to the `router.navigate` method that navigates
 
 You can also preserve query parameters and fragments across navigations without having to provide them
 again when navigating. In the `LoginComponent`, you'll add an *object* as the
-second argument in the `router.navigate` function
+second argument in the `router.navigateUrl()` function
 and provide the `queryParamsHandling` and `preserveFragment` to pass along the current query parameters
 and fragment to the next route.