Routing

We received new requirements for our Tour of Heroes application:

When we’re done, users will be able to navigate the app like this:

View navigations

We'll add Angular’s Router to our app to satisfy these requirements.

The Routing and Navigation chapter covers the router in more detail than we will in this tutorial.

Run the for this part.

To see the URL changes in the browser address bar of the live example, open it again in the Plunker editor by clicking the icon in the upper right, then pop out the preview window by clicking the blue 'X' button in the upper right corner.

pop out the window
pop out the window

Where We Left Off

Before we continue with our Tour of Heroes, let’s verify that we have the following structure after adding our hero service and hero detail component. If not, we’ll need to go back and follow the previous chapters.

angular-tour-of-heroes
src
app
app.component.ts
app.module.ts
hero.service.ts
hero.ts
hero-detail.component.ts
mock-heroes.ts
main.ts
index.html
styles.css
systemjs.config.js
tsconfig.json
node_modules ...
package.json

Keep the app transpiling and running

Open a terminal/console window and enter the following command to start the TypeScript compiler, start the server, and watch for changes:

npm start

The application runs and updates automatically as we continue to build the Tour of Heroes.

Action plan

Here's our plan:

Routing is another name for navigation. The router is the mechanism for navigating from view to view.

Splitting the AppComponent

Our current app loads AppComponent and immediately displays the list of heroes.

Our revised app should present a shell with a choice of views (Dashboard and Heroes) and then default to one of them.

The AppComponent should only handle navigation. Let's move the display of Heroes out of AppComponent and into its own HeroesComponent.

HeroesComponent

AppComponent is already dedicated to Heroes. Instead of moving anything out of AppComponent, we'll just rename it HeroesComponent and create a new AppComponent shell separately.

The steps are to rename:

src/app/heroes.component.ts (showing renamings only)

@Component({ selector: 'my-heroes', }) export class HeroesComponent implements OnInit { }

Create AppComponent

The new AppComponent will be the application shell. It will have some navigation links at the top and a display area below for the pages we navigate to.

The initial steps are:

Our first draft looks like this:

import { Component } from '@angular/core'; @Component({ selector: 'my-app', template: ` <h1>{{title}}</h1> <my-heroes></my-heroes> ` }) export class AppComponent { title = 'Tour of Heroes'; } import { NgModule } from '@angular/core'; import { BrowserModule } from '@angular/platform-browser'; import { FormsModule } from '@angular/forms'; import { AppComponent } from './app.component'; import { HeroDetailComponent } from './hero-detail.component'; import { HeroesComponent } from './heroes.component'; import { HeroService } from './hero.service'; @NgModule({ imports: [ BrowserModule, FormsModule ], declarations: [ AppComponent, HeroDetailComponent, HeroesComponent ], providers: [ HeroService ], bootstrap: [ AppComponent ] }) export class AppModule { }

The app still runs and still displays heroes. Our refactoring of AppComponent into a new AppComponent and a HeroesComponent worked! We have done no harm.

Add Routing

We're ready to take the next step. Instead of displaying heroes automatically, we'd like to show them after the user clicks a button. In other words, we'd like to navigate to the list of heroes.

We'll need the Angular Router.

The Angular router is an external, optional Angular NgModule called RouterModule. The router is a combination of multiple provided services (RouterModule), multiple directives (RouterOutlet, RouterLink, RouterLinkActive), and a configuration (Routes). We'll configure our routes first.

<base href>

Open index.html and ensure there is a <base href="..."> element (or a script that dynamically sets this element) at the top of the <head> section.

src/index.html (base-href)

<head> <base href="/">
base href is essential

See the base href section of the router guide to learn why this matters, and what to add if the base element is missing.

Configure routes

Our application doesn't have any routes yet. We'll start by creating a configuration for the application routes.

Routes tell the router which views to display when a user clicks a link or pastes a URL into the browser address bar.

Let's define our first route as a route to the heroes component:

src/app/app.module.ts (heroes route)

import { RouterModule } from '@angular/router'; RouterModule.forRoot([ { path: 'heroes', component: HeroesComponent } ])

The Routes are an array of route definitions. We have only one route definition at the moment but rest assured, we'll add more.

This route definition has the following parts:

Learn more about defining routes with Routes in the Routing chapter.

Make the router available

We've setup the initial route configuration. Now we'll add it to our AppModule. We'll add our configured RouterModule to the AppModule imports array.

src/app/app.module.ts (app routing)

import { NgModule } from '@angular/core'; import { BrowserModule } from '@angular/platform-browser'; import { FormsModule } from '@angular/forms'; import { RouterModule } from '@angular/router'; import { AppComponent } from './app.component'; import { HeroDetailComponent } from './hero-detail.component'; import { HeroesComponent } from './heroes.component'; import { HeroService } from './hero.service'; @NgModule({ imports: [ BrowserModule, FormsModule, RouterModule.forRoot([ { path: 'heroes', component: HeroesComponent } ]) ], declarations: [ AppComponent, HeroDetailComponent, HeroesComponent ], providers: [ HeroService ], bootstrap: [ AppComponent ] }) export class AppModule { }

We use the forRoot method because we're providing a configured router at the root of the application. The forRoot method gives us the Router service providers and directives needed for routing, and performs the initial navigation based on the current browser URL.

Router Outlet

If we paste the path, /heroes, into the browser address bar, the router should match it to the heroes route and display the HeroesComponent. But where?

We have to tell it where by adding a <router-outlet> element to the bottom of the template. RouterOutlet is one of the directives provided by the RouterModule. The router displays each component immediately below the <router-outlet> as we navigate through the application.

We don't really expect users to paste a route URL into the address bar. We add an anchor tag to the template which, when clicked, triggers navigation to the HeroesComponent.

The revised template looks like this:

src/app/app.component.ts (template-v2)

template: ` <h1>{{title}}</h1> <a routerLink="/heroes">Heroes</a> <router-outlet></router-outlet> `

Notice the routerLink binding in the anchor tag. We bind the RouterLink directive (another of the RouterModule directives) to a string that tells the router where to navigate when the user clicks the link.

Since our link is not dynamic, we define a routing instruction with a one-time binding to our route path. Looking back at the route configuration, we confirm that '/heroes' is the path of the route to the HeroesComponent.

Learn more about dynamic router links and the link parameters array in the Routing chapter.

Refresh the browser. We see only the app title and heroes link. We don't see the heroes list.

The browser's address bar shows /. The route path to HeroesComponent is /heroes, not /. We don't have a route that matches the path /, so there is nothing to show. That's something we'll want to fix.

We click the Heroes navigation link, the browser bar updates to /heroes, and now we see the list of heroes. We are navigating at last!

At this stage, our AppComponent looks like this.

src/app/app.component.ts (v2)

import { Component } from '@angular/core'; @Component({ selector: 'my-app', template: ` <h1>{{title}}</h1> <a routerLink="/heroes">Heroes</a> <router-outlet></router-outlet> ` }) export class AppComponent { title = 'Tour of Heroes'; }

The AppComponent is now attached to a router and displaying routed views. For this reason and to distinguish it from other kinds of components, we call this type of component a Router Component.

Add a Dashboard

Routing only makes sense when we have multiple views. We need another view.

Create a placeholder DashboardComponent that gives us something to navigate to and from.

src/app/dashboard.component.ts (v1)

import { Component } from '@angular/core'; @Component({ selector: 'my-dashboard', template: '<h3>My Dashboard</h3>' }) export class DashboardComponent { }

We’ll come back and make it more useful later.

Configure the dashboard route

Go back to app.module.ts and teach it to navigate to the dashboard.

Import the dashboard component and add the following route definition to the Routes array of definitions.

src/app/app.module.ts (Dashboard route)

{ path: 'dashboard', component: DashboardComponent },

Also import and add DashboardComponent to our AppModule's declarations.

src/app/app.module.ts (dashboard)

declarations: [ AppComponent, DashboardComponent, HeroDetailComponent, HeroesComponent ],

redirectTo

We want the app to show the dashboard when it starts and we want to see a nice URL in the browser address bar that says /dashboard. Remember that the browser launches with / in the address bar.

We can use a redirect route to make this happen. Add the following to our array of route definitions:

src/app/app.module.ts (redirect)

{ path: '', redirectTo: '/dashboard', pathMatch: 'full' },

Learn about the redirects in the Routing chapter.

Add navigation to the template

Finally, add a dashboard navigation link to the template, just above the Heroes link.

src/app/app.component.ts (template-v3)

template: ` <h1>{{title}}</h1> <nav> <a routerLink="/dashboard">Dashboard</a> <a routerLink="/heroes">Heroes</a> </nav> <router-outlet></router-outlet> `

We nested the two links within <nav> tags. They don't do anything yet but they'll be convenient when we style the links a little later in the chapter.

To see these changes in your browser, go to the application root (/) and reload. The app displays the dashboard and we can navigate between the dashboard and the heroes.

Dashboard Top Heroes

Let’s spice up the dashboard by displaying the top four heroes at a glance.

Replace the template metadata with a templateUrl property that points to a new template file.

Set the moduleId property to module.id for module-relative loading of the templateUrl.

src/app/dashboard.component.ts (metadata)

@Component({ moduleId: module.id, selector: 'my-dashboard', templateUrl: './dashboard.component.html', })

Create that file with this content:

src/app/dashboard.component.html

<h3>Top Heroes</h3> <div class="grid grid-pad"> <div *ngFor="let hero of heroes" class="col-1-4"> <div class="module hero"> <h4>{{hero.name}}</h4> </div> </div> </div>

We use *ngFor once again to iterate over a list of heroes and display their names. We added extra <div> elements to help with styling later in this chapter.

Share the HeroService

We'd like to re-use the HeroService to populate the component's heroes array.

Recall earlier in the chapter that we removed the HeroService from the providers array of HeroesComponent and added it to the providers array of AppModule.

That move created a singleton HeroService instance, available to all components of the application. Angular will inject HeroService and we'll use it here in the DashboardComponent.

Get heroes

Open dashboard.component.ts and add the requisite import statements.

src/app/dashboard.component.ts (imports)

import { Component, OnInit } from '@angular/core'; import { Hero } from './hero'; import { HeroService } from './hero.service';

Now implement the DashboardComponent class like this:

src/app/dashboard.component.ts (class)

export class DashboardComponent implements OnInit { heroes: Hero[] = []; constructor(private heroService: HeroService) { } ngOnInit(): void { this.heroService.getHeroes() .then(heroes => this.heroes = heroes.slice(1, 5)); } }

We've seen this kind of logic before in the HeroesComponent:

In this dashboard we cherry-pick four heroes (2nd, 3rd, 4th, and 5th) with the Array.slice method.

Refresh the browser and see four heroes in the new dashboard.

Although we display the details of a selected hero at the bottom of the HeroesComponent, we don't yet navigate to the HeroDetailComponent in the three ways specified in our requirements:

  1. from the Dashboard to a selected hero.
  2. from the Heroes list to a selected hero.
  3. from a "deep link" URL pasted into the browser address bar.

Adding a hero-detail route seems like an obvious place to start.

Routing to a hero detail

We'll add a route to the HeroDetailComponent in app.module.ts where our other routes are configured.

The new route is a bit unusual in that we must tell the HeroDetailComponent which hero to show. We didn't have to tell the HeroesComponent or the DashboardComponent anything.

At the moment the parent HeroesComponent sets the component's hero property to a hero object with a binding like this.

<my-hero-detail [hero]="selectedHero"></my-hero-detail>

That clearly won't work in any of our routing scenarios. Certainly not the last one; we can't embed an entire hero object in the URL! Nor would we want to.

Parameterized route

We can add the hero's id to the URL. When routing to the hero whose id is 11, we could expect to see a URL such as this:

/detail/11

The /detail/ part of that URL is constant. The trailing numeric id part changes from hero to hero. We need to represent that variable part of the route with a parameter (or token) that stands for the hero's id.

Configure a Route with a Parameter

Here's the route definition we'll use.

src/app/app.module.ts (hero detail)

{ path: 'detail/:id', component: HeroDetailComponent },

The colon (:) in the path indicates that :id is a placeholder to be filled with a specific hero id when navigating to the HeroDetailComponent.

We're finished with the application routes.

We won't add a 'Hero Detail' link to the template because users don't click a navigation link to view a particular hero. They click a hero whether that hero is displayed on the dashboard or in the heroes list.

We'll get to those hero clicks later in the chapter. There's no point in working on them until the HeroDetailComponent is ready to be navigated to.

That will require an HeroDetailComponent overhaul.

Revise the HeroDetailComponent

Before we rewrite the HeroDetailComponent, let's review what it looks like now:

src/app/hero-detail.component.ts (current)

import { Component, Input } from '@angular/core'; import { Hero } from './hero'; @Component({ selector: 'my-hero-detail', template: ` <div *ngIf="hero"> <h2>{{hero.name}} details!</h2> <div> <label>id: </label>{{hero.id}} </div> <div> <label>name: </label> <input [(ngModel)]="hero.name" placeholder="name"/> </div> </div> ` }) export class HeroDetailComponent { @Input() hero: Hero; }

The template won't change. We'll display a hero the same way. The big changes are driven by how we get the hero.

We will no longer receive the hero in a parent component property binding. The new HeroDetailComponent should take the id parameter from the params observable in the ActivatedRoute service and use the HeroService to fetch the hero with that id.

First, add the requisite imports:

// Keep the Input import for now, we'll remove it later: import { Component, Input, OnInit } from '@angular/core'; import { ActivatedRoute, Params } from '@angular/router'; import { Location } from '@angular/common'; import { HeroService } from './hero.service';

Let's have the ActivatedRoute service, the HeroService and the Location service injected into the constructor, saving their values in private fields:

src/app/hero-detail.component.ts (constructor)

constructor( private heroService: HeroService, private route: ActivatedRoute, private location: Location ) {}

Also import the switchMap operator to use later with the route parameters Observable.

src/app/hero-detail.component.ts (switchMap import)

import 'rxjs/add/operator/switchMap';

We tell the class that we want to implement the OnInit interface.

export class HeroDetailComponent implements OnInit {

Inside the ngOnInit lifecycle hook, we use the params observable to extract the id parameter value from the ActivatedRoute service and use the HeroService to fetch the hero with that id.

src/app/hero-detail.component.ts (ngOnInit)

ngOnInit(): void { this.route.params .switchMap((params: Params) => this.heroService.getHero(+params['id'])) .subscribe(hero => this.hero = hero); }

Note how the switchMap operator maps the id in the observable route parameters to a new Observable, the result of the HeroService.getHero method.

If the user re-navigates to this component while a getHero request is still inflight, switchMap cancels that old request before calling HeroService.getHero again.

The hero id is a number. Route parameters are always strings. So we convert the route parameter value to a number with the JavaScript (+) operator.

Do I need to unsubscribe?

The Router manages the observables it provides and localizes the subscriptions. The subscriptions are cleaned up when the component is destroyed, protecting against memory leaks, so we don't need to unsubscribe from the route params Observable.

Add HeroService.getHero

The problem with this bit of code is that HeroService doesn't have a getHero method! We better fix that quickly before someone notices that we broke the app.

Open HeroService and add a getHero method that filters the heroes list from getHeroes by id:

src/app/hero.service.ts (getHero)

getHero(id: number): Promise<Hero> { return this.getHeroes() .then(heroes => heroes.find(hero => hero.id === id)); }

Let's return to the HeroDetailComponent to clean up loose ends.

Find our way back

We can navigate to the HeroDetailComponent in several ways. How do we navigate somewhere else when we're done?

The user could click one of the two links in the AppComponent. Or click the browser's back button. We'll add a third option, a goBack method that navigates backward one step in the browser's history stack using the Location service we injected previously.

src/app/hero-detail.component.ts (goBack)

goBack(): void { this.location.back(); }

Going back too far could take us out of the application. That's acceptable in a demo. We'd guard against it in a real application, perhaps with the CanDeactivate guard.

Then we wire this method with an event binding to a Back button that we add to the bottom of the component template.

<button (click)="goBack()">Back</button>

Modifying the template to add this button spurs us to take one more incremental improvement and migrate the template to its own file, called hero-detail.component.html:

src/app/hero-detail.component.html

<div *ngIf="hero"> <h2>{{hero.name}} details!</h2> <div> <label>id: </label>{{hero.id}}</div> <div> <label>name: </label> <input [(ngModel)]="hero.name" placeholder="name" /> </div> <button (click)="goBack()">Back</button> </div>

We update the component metadata with a moduleId and a templateUrl pointing to the template file that we just created.

src/app/hero-detail.component.ts (metadata)

@Component({ moduleId: module.id, selector: 'my-hero-detail', templateUrl: './hero-detail.component.html', })

Refresh the browser and see the results.

Select a Dashboard Hero

When a user selects a hero in the dashboard, the app should navigate to the HeroDetailComponent to view and edit the selected hero.

Although the dashboard heroes are presented as button-like blocks, they should behave like anchor tags. When hovering over a hero block, the target URL should display in the browser status bar and the user should be able to copy the link or open the hero detail view in a new tab.

To achieve this effect, reopen the dashboard.component.html and replace the repeated <div *ngFor...> tags with <a> tags. The opening <a> tag looks like this:

src/app/dashboard.component.html (repeated <a> tag)

<a *ngFor="let hero of heroes" [routerLink]="['/detail', hero.id]" class="col-1-4">

Notice the [routerLink] binding.

Top level navigation in the AppComponent template has router links set to fixed paths of the destination routes, "/dashboard" and "/heroes".

This time, we're binding to an expression containing a link parameters array. The array has two elements, the path of the destination route and a route parameter set to the value of the current hero's id.

The two array items align with the path and :id token in the parameterized hero detail route definition we added to app.module.ts earlier in the chapter:

src/app/app.module.ts (hero detail)

{ path: 'detail/:id', component: HeroDetailComponent },

Refresh the browser and select a hero from the dashboard; the app should navigate directly to that hero’s details.

Refactor routes to a Routing Module

Almost 20 lines of AppModule are devoted to configuring four routes. Most applications have many more routes and they add guard services to protect against unwanted or unauthorized navigations. Routing considerations could quickly dominate this module and obscure its primary purpose which is to establish key facts about the entire app for the Angular compiler.

We should refactor the routing configuration into its own class. What kind of class? The current RouterModule.forRoot() produces an Angular ModuleWithProviders which suggests that a class dedicated to routing should be some kind of module. It should be a Routing Module.

By convention the name of a Routing Module contains the word "Routing" and aligns with the name of the module that declares the components navigated to.

Create an app-routing.module.ts file as a sibling to app.module.ts. Give it the following contents extracted from the AppModule class:

src/app/app-routing.module.ts

import { NgModule } from '@angular/core'; import { RouterModule, Routes } from '@angular/router'; import { DashboardComponent } from './dashboard.component'; import { HeroesComponent } from './heroes.component'; import { HeroDetailComponent } from './hero-detail.component'; const routes: Routes = [ { path: '', redirectTo: '/dashboard', pathMatch: 'full' }, { path: 'dashboard', component: DashboardComponent }, { path: 'detail/:id', component: HeroDetailComponent }, { path: 'heroes', component: HeroesComponent } ]; @NgModule({ imports: [ RouterModule.forRoot(routes) ], exports: [ RouterModule ] }) export class AppRoutingModule {}

Noteworthy points, typical of Routing Modules:

Update AppModule

Now delete the routing configuration from AppModule and import the AppRoutingModule (both with an ES import statement and by adding it to the NgModule.imports list).

Here is the revised AppModule, compared to its pre-refactor state:

import { NgModule } from '@angular/core'; import { BrowserModule } from '@angular/platform-browser'; import { FormsModule } from '@angular/forms'; import { AppComponent } from './app.component'; import { DashboardComponent } from './dashboard.component'; import { HeroDetailComponent } from './hero-detail.component'; import { HeroesComponent } from './heroes.component'; import { HeroService } from './hero.service'; import { AppRoutingModule } from './app-routing.module'; @NgModule({ imports: [ BrowserModule, FormsModule, AppRoutingModule ], declarations: [ AppComponent, DashboardComponent, HeroDetailComponent, HeroesComponent ], providers: [ HeroService ], bootstrap: [ AppComponent ] }) export class AppModule { } import { NgModule } from '@angular/core'; import { BrowserModule } from '@angular/platform-browser'; import { FormsModule } from '@angular/forms'; import { RouterModule } from '@angular/router'; import { AppComponent } from './app.component'; import { HeroDetailComponent } from './hero-detail.component'; import { DashboardComponent } from './dashboard.component'; import { HeroesComponent } from './heroes.component'; import { HeroService } from './hero.service'; @NgModule({ imports: [ BrowserModule, FormsModule, RouterModule.forRoot([ { path: '', redirectTo: '/dashboard', pathMatch: 'full' }, { path: 'dashboard', component: DashboardComponent }, { path: 'detail/:id', component: HeroDetailComponent }, { path: 'heroes', component: HeroesComponent } ]) ], declarations: [ AppComponent, DashboardComponent, HeroDetailComponent, HeroesComponent ], providers: [ HeroService ], bootstrap: [ AppComponent ] }) export class AppModule { }

It's simpler and focused on identifying the key pieces of the application.

Select a Hero in the HeroesComponent

Earlier we added the ability to select a hero from the dashboard. We'll do something similar in the HeroesComponent.

The HeroesComponent template exhibits a "master/detail" style with the list of heroes at the top and details of the selected hero below.

src/app/heroes.component.ts (current template)

template: ` <h1>{{title}}</h1> <h2>My Heroes</h2> <ul class="heroes"> <li *ngFor="let hero of heroes" [class.selected]="hero === selectedHero" (click)="onSelect(hero)"> <span class="badge">{{hero.id}}</span> {{hero.name}} </li> </ul> <my-hero-detail [hero]="selectedHero"></my-hero-detail> `,

Our goal is to move the detail to its own view and navigate to it when the user decides to edit a selected hero.

Delete the <h1> at the top (we forgot about it during the AppComponent-to-HeroesComponent conversion).

Delete the last line of the template with the <my-hero-detail> tags.

We'll no longer show the full HeroDetailComponent here. We're going to display the hero detail on its own page and route to it as we did in the dashboard.

We'll throw in a small twist for variety. We are keeping the "master/detail" style but shrinking the detail to a "mini", read-only version. When the user selects a hero from the list, we don't go to the detail page. We show a mini-detail on this page instead and make the user click a button to navigate to the full detail page.

Add the mini-detail

Add the following HTML fragment at the bottom of the template where the <my-hero-detail> used to be:

<div *ngIf="selectedHero"> <h2> {{selectedHero.name | uppercase}} is my hero </h2> <button (click)="gotoDetail()">View Details</button> </div>

After clicking a hero, the user should see something like this below the hero list:

Mini Hero Detail

Format with the uppercase pipe

Notice that the hero's name is displayed in CAPITAL LETTERS. That's the effect of the uppercase pipe that we slipped into the interpolation binding. Look for it right after the pipe operator ( | ).

{{selectedHero.name | uppercase}} is my hero

Pipes are a good way to format strings, currency amounts, dates and other display data. Angular ships with several pipes and we can write our own.

Learn about pipes in the Pipes chapter.

Move content out of the component file

We are not done. We still have to update the component class to support navigation to the HeroDetailComponent when the user clicks the View Details button.

This component file is really big. Most of it is either template or CSS styles. It's difficult to find the component logic amidst the noise of HTML and CSS.

Let's migrate the template and the styles to their own files before we make any more changes:

  1. Cut-and-paste the template contents into a new heroes.component.html file.
  2. Cut-and-paste the styles contents into a new heroes.component.css file.
  3. Set the component metadata's templateUrl and styleUrls properties to refer to both files.
  4. . Set the moduleId property to module.id so that templateUrl and styleUrls are relative to the component.

The styleUrls property is an array of style file names (with paths). We could list multiple style files from different locations if we needed them.

src/app/heroes.component.ts (revised metadata)

@Component({ moduleId: module.id, selector: 'my-heroes', templateUrl: './heroes.component.html', styleUrls: [ './heroes.component.css' ] })

Update the HeroesComponent class.

The HeroesComponent navigates to the HeroDetailComponent in response to a button click. The button's click event is bound to a gotoDetail method that navigates imperatively by telling the router where to go.

This approach requires some changes to the component class:

  1. Import the router from the Angular router library
  2. Inject the router in the constructor (along with the HeroService)
  3. Implement gotoDetail by calling the router.navigate method

src/app/heroes.component.ts (gotoDetail)

gotoDetail(): void { this.router.navigate(['/detail', this.selectedHero.id]); }

Note that we're passing a two-element link parameters array — a path and the route parameter — to the router.navigate method just as we did in the [routerLink] binding back in the DashboardComponent. Here's the fully revised HeroesComponent class:

src/app/heroes.component.ts (class)

export class HeroesComponent implements OnInit { heroes: Hero[]; selectedHero: Hero; constructor( private router: Router, private heroService: HeroService) { } getHeroes(): void { this.heroService.getHeroes().then(heroes => this.heroes = heroes); } ngOnInit(): void { this.getHeroes(); } onSelect(hero: Hero): void { this.selectedHero = hero; } gotoDetail(): void { this.router.navigate(['/detail', this.selectedHero.id]); } }

Refresh the browser and start clicking. We can navigate around the app, from the dashboard to hero details and back, for heroes list to the mini-detail to the hero details and back to the heroes again. We can jump back and forth between the dashboard and the heroes.

We've met all of the navigational requirements that propelled this chapter.

Styling the App

The app is functional but pretty ugly. Our creative designer team provided some CSS files to make it look better.

A Dashboard with Style

The designers think we should display the dashboard heroes in a row of rectangles. They've given us ~60 lines of CSS for this purpose including some simple media queries for responsive design.

If we paste these ~60 lines into the component styles metadata, they'll completely obscure the component logic. Let's not do that. It's easier to edit CSS in a separate *.css file anyway.

Add a dashboard.component.css file to the app folder and reference that file in the component metadata's styleUrls array property like this:

src/app/dashboard.component.ts (styleUrls)

styleUrls: [ './dashboard.component.css' ]

Stylish Hero Details

The designers also gave us CSS styles specifically for the HeroDetailComponent.

Add a hero-detail.component.css to the app folder and refer to that file inside the styleUrls array as we did for DashboardComponent. Let's also remove the hero property @Input decorator and its import while we are at it.

Here's the content for the aforementioned component CSS files.

label { display: inline-block; width: 3em; margin: .5em 0; color: #607D8B; font-weight: bold; } input { height: 2em; font-size: 1em; padding-left: .4em; } button { margin-top: 20px; font-family: Arial; background-color: #eee; border: none; padding: 5px 10px; border-radius: 4px; cursor: pointer; cursor: hand; } button:hover { background-color: #cfd8dc; } button:disabled { background-color: #eee; color: #ccc; cursor: auto; } [class*='col-'] { float: left; padding-right: 20px; padding-bottom: 20px; } [class*='col-']:last-of-type { padding-right: 0; } a { text-decoration: none; } *, *:after, *:before { -webkit-box-sizing: border-box; -moz-box-sizing: border-box; box-sizing: border-box; } h3 { text-align: center; margin-bottom: 0; } h4 { position: relative; } .grid { margin: 0; } .col-1-4 { width: 25%; } .module { padding: 20px; text-align: center; color: #eee; max-height: 120px; min-width: 120px; background-color: #607D8B; border-radius: 2px; } .module:hover { background-color: #EEE; cursor: pointer; color: #607d8b; } .grid-pad { padding: 10px 0; } .grid-pad > [class*='col-']:last-of-type { padding-right: 20px; } @media (max-width: 600px) { .module { font-size: 10px; max-height: 75px; } } @media (max-width: 1024px) { .grid { margin: 0; } .module { min-width: 60px; } }

The designers gave us CSS to make the navigation links in our AppComponent look more like selectable buttons. We cooperated by surrounding those links in <nav> tags.

Add a app.component.css file to the app folder with the following content.

src/app/app.component.css (navigation styles)

h1 { font-size: 1.2em; color: #999; margin-bottom: 0; } h2 { font-size: 2em; margin-top: 0; padding-top: 0; } nav a { padding: 5px 10px; text-decoration: none; margin-top: 10px; display: inline-block; background-color: #eee; border-radius: 4px; } nav a:visited, a:link { color: #607D8B; } nav a:hover { color: #039be5; background-color: #CFD8DC; } nav a.active { color: #039be5; }

The routerLinkActive directive

The Angular Router provides a routerLinkActive directive we can use to add a class to the HTML navigation element whose route matches the active route. All we have to do is define the style for it. Sweet!

src/app/app.component.ts (active router links)

template: ` <h1>{{title}}</h1> <nav> <a routerLink="/dashboard" routerLinkActive="active">Dashboard</a> <a routerLink="/heroes" routerLinkActive="active">Heroes</a> </nav> <router-outlet></router-outlet> `,

First add moduleId: module.id to the @Component metadata of the AppComponent to enable module-relative file URLs. Then add a styleUrls property that points to this CSS file as follows.

src/app/app.component.ts (styleUrls)

styleUrls: ['./app.component.css'],

Global application styles

When we add styles to a component, we're keeping everything a component needs — HTML, the CSS, the code — together in one convenient place. It's pretty easy to package it all up and re-use the component somewhere else.

We can also create styles at the application level outside of any component.

Our designers provided some basic styles to apply to elements across the entire app. These correspond to the full set of master styles that we installed earlier during setup. Here is an excerpt:

src/styles.css (excerpt)

/* Master Styles */ h1 { color: #369; font-family: Arial, Helvetica, sans-serif; font-size: 250%; } h2, h3 { color: #444; font-family: Arial, Helvetica, sans-serif; font-weight: lighter; } body { margin: 2em; } body, input[text], button { color: #888; font-family: Cambria, Georgia; } /* . . . */ /* everywhere else */ * { font-family: Arial, Helvetica, sans-serif; }

Create the file styles.css, if it doesn't exist already. Ensure that it contains the master styles given here.

If necessary, also edit index.html to refer to this stylesheet.

src/index.html (link ref)

<link rel="stylesheet" href="styles.css">

Look at the app now. Our dashboard, heroes, and navigation links are styling!

View navigations

Application structure and code

Review the sample source code in the for this chapter. Verify that we have the following structure:

angular-tour-of-heroes
src
app
app.component.css
app.component.ts
app.module.ts
app-routing.module.ts
dashboard.component.css
dashboard.component.html
dashboard.component.ts
hero.service.ts
hero.ts
hero-detail.component.css
hero-detail.component.html
hero-detail.component.ts
heroes.component.css
heroes.component.html
heroes.component.ts
mock-heroes.ts
main.ts
index.html
styles.css
systemjs.config.js
tsconfig.json
node_modules ...
package.json

Recap

The Road Behind

We travelled a great distance in this chapter

The Road Ahead

We have much of the foundation we need to build an application. We're still missing a key piece: remote data access.

In the next chapter, we’ll replace our mock data with data retrieved from a server using http.

Next Step

HTTP