HTTP

Getting and saving data

Our stakeholders appreciate our progress. Now they want to get the hero data from a server, let users add, edit, and delete heroes, and save these changes back to the server.

In this chapter we teach our application to make the corresponding HTTP calls to a remote server's web API.

Run the for this part.

Where We Left Off

In the previous chapter, we learned to navigate between the dashboard and the fixed heroes list, editing a selected hero along the way. That's our starting point for this chapter.

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.

Providing HTTP Services

The HttpModule is not a core Angular module. It's Angular's optional approach to web access and it exists as a separate add-on module called @angular/http, shipped in a separate script file as part of the Angular npm package.

Fortunately we're ready to import from @angular/http because systemjs.config configured SystemJS to load that library when we need it.

Register for HTTP services

Our app will depend upon the Angular http service which itself depends upon other supporting services. The HttpModule from @angular/http library holds providers for a complete set of HTTP services.

We should be able to access these services from anywhere in the application. So we register them all by adding HttpModule to the imports list of the AppModule where we bootstrap the application and its root AppComponent.

src/app/app.module.ts (v1)

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

Notice that we supply HttpModule as part of the imports array in root NgModule AppModule.

Simulating the web API

We recommend registering application-wide services in the root AppModule providers. Here we're registering in main for a special reason.

Our application is in the early stages of development and far from ready for production. We don't even have a web server that can handle requests for heroes. Until we do, we'll have to fake it.

We're going to trick the HTTP client into fetching and saving data from a mock service, the in-memory web API. The application itself doesn't need to know and shouldn't know about this. So we'll slip the in-memory web API into the configuration above the AppComponent.

Here is a version of src/app/app.module.ts that performs this trick:

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

import { NgModule } from '@angular/core'; import { BrowserModule } from '@angular/platform-browser'; import { FormsModule } from '@angular/forms'; import { HttpModule } from '@angular/http'; import { AppRoutingModule } from './app-routing.module'; // Imports for loading & configuring the in-memory web api import { InMemoryWebApiModule } from 'angular-in-memory-web-api'; import { InMemoryDataService } from './in-memory-data.service'; import { AppComponent } from './app.component'; import { DashboardComponent } from './dashboard.component'; import { HeroesComponent } from './heroes.component'; import { HeroDetailComponent } from './hero-detail.component'; import { HeroService } from './hero.service'; @NgModule({ imports: [ BrowserModule, FormsModule, HttpModule, InMemoryWebApiModule.forRoot(InMemoryDataService), AppRoutingModule ], declarations: [ AppComponent, DashboardComponent, HeroDetailComponent, HeroesComponent, ], providers: [ HeroService ], bootstrap: [ AppComponent ] }) export class AppModule { }

Rather than require a real API server, this example simulates communication with the remote server by adding the InMemoryWebApiModule to the module imports, effectively replacing the Http client's XHR backend service with an in-memory alternative.

InMemoryWebApiModule.forRoot(InMemoryDataService),

The forRoot configuration method takes an InMemoryDataService class that primes the in-memory database as follows:

src/app/in-memory-data.service.ts

import { InMemoryDbService } from 'angular-in-memory-web-api'; export class InMemoryDataService implements InMemoryDbService { createDb() { let heroes = [ {id: 11, name: 'Mr. Nice'}, {id: 12, name: 'Narco'}, {id: 13, name: 'Bombasto'}, {id: 14, name: 'Celeritas'}, {id: 15, name: 'Magneta'}, {id: 16, name: 'RubberMan'}, {id: 17, name: 'Dynama'}, {id: 18, name: 'Dr IQ'}, {id: 19, name: 'Magma'}, {id: 20, name: 'Tornado'} ]; return {heroes}; } }

This file replaces the mock-heroes.ts which is now safe to delete.

This chapter is an introduction to the Angular HTTP library. Please don't be distracted by the details of this backend substitution. Just follow along with the example.

Learn more later about the in-memory web API in the HTTP client chapter. Remember, the in-memory web API is only useful in the early stages of development and for demonstrations such as this Tour of Heroes. Skip it when you have a real web API server.

Heroes and HTTP

Look at our current HeroService implementation

getHeroes(): Promise<Hero[]> { return Promise.resolve(HEROES); }

We returned a Promise resolved with mock heroes. It may have seemed like overkill at the time, but we were anticipating the day when we fetched heroes with an HTTP client and we knew that would have to be an asynchronous operation.

That day has arrived! Let's convert getHeroes() to use HTTP.

src/app/hero.service.ts (updated getHeroes and new class members)

private heroesUrl = 'api/heroes'; // URL to web api constructor(private http: Http) { } getHeroes(): Promise<Hero[]> { return this.http.get(this.heroesUrl) .toPromise() .then(response => response.json().data as Hero[]) .catch(this.handleError); } private handleError(error: any): Promise<any> { console.error('An error occurred', error); // for demo purposes only return Promise.reject(error.message || error); }

Our updated import statements are now:

src/app/hero.service.ts (updated imports)

import { Injectable } from '@angular/core'; import { Headers, Http } from '@angular/http'; import 'rxjs/add/operator/toPromise'; import { Hero } from './hero';

Refresh the browser, and the hero data should be successfully loaded from the mock server.

HTTP Promise

We're still returning a Promise but we're creating it differently.

The Angular http.get returns an RxJS Observable. Observables are a powerful way to manage asynchronous data flows. We'll learn about Observables later in this chapter.

For now we get back on familiar ground by immediately converting that Observable to a Promise using the toPromise operator.

.toPromise()

Unfortunately, the Angular Observable doesn't have a toPromise operator ... not out of the box. The Angular Observable is a bare-bones implementation.

There are scores of operators like toPromise that extend Observable with useful capabilities. If we want those capabilities, we have to add the operators ourselves. That's as easy as importing them from the RxJS library like this:

import 'rxjs/add/operator/toPromise';

You'll add more operators, and learn why you must do so, later in this tutorial.

Extracting the data in the then callback

In the promise's then callback we call the json method of the HTTP Response to extract the data within the response.

.then(response => response.json().data as Hero[])

That response JSON has a single data property. The data property holds the array of heroes that the caller really wants. So we grab that array and return it as the resolved Promise value.

Pay close attention to the shape of the data returned by the server. This particular in-memory web API example happens to return an object with a data property. Your API might return something else. Adjust the code to match your web API.

The caller is unaware of these machinations. It receives a Promise of heroes just as it did before. It has no idea that we fetched the heroes from the (mock) server. It knows nothing of the twists and turns required to convert the HTTP response into heroes. Such is the beauty and purpose of delegating data access to a service like this HeroService.

Error Handling

At the end of getHeroes() we catch server failures and pass them to an error handler:

.catch(this.handleError);

This is a critical step! We must anticipate HTTP failures as they happen frequently for reasons beyond our control.

private handleError(error: any): Promise<any> { console.error('An error occurred', error); // for demo purposes only return Promise.reject(error.message || error); }

In this demo service we log the error to the console; we would do better in real life.

We've also decided to return a user friendly form of the error to the caller in a rejected promise so that the caller can display a proper error message to the user.

Get hero by id

The HeroDetailComponent asks the HeroService to fetch a single hero to edit.

The HeroService currently fetches all heroes and then finds the desired hero by filtering for the one with the matching id. That's fine in a simulation. It's wasteful to ask a real server for all heroes when we only want one. Most web APIs support a get-by-id request in the form api/hero/:id (e.g., api/hero/11).

Update the HeroService.getHero method to make a get-by-id request, applying what we just learned to write getHeroes:

getHero(id: number): Promise<Hero> { const url = `${this.heroesUrl}/${id}`; return this.http.get(url) .toPromise() .then(response => response.json().data as Hero) .catch(this.handleError); }

It's almost the same as getHeroes. The URL identifies which hero the server should update by encoding the hero id into the URL to match the api/hero/:id pattern.

We also adjust to the fact that the data in the response is a single hero object rather than an array.

Unchanged getHeroes API

Although we made significant internal changes to getHeroes() and getHero(), the public signatures did not change. We still return a Promise from both methods. We won't have to update any of the components that call them.

Our stakeholders are thrilled with the web API integration so far. Now they want the ability to create and delete heroes.

Let's see first what happens when we try to update a hero's details.

Update hero details

We can edit a hero's name already in the hero detail view. Go ahead and try it. As we type, the hero name is updated in the view heading. But when we hit the Back button, the changes are lost!

Updates weren't lost before. What changed? When the app used a list of mock heroes, updates were applied directly to the hero objects within the single, app-wide, shared list. Now that we are fetching data from a server, if we want changes to persist, we'll need to write them back to the server.

Save hero details

Let's ensure that edits to a hero's name aren't lost. Start by adding, to the end of the hero detail template, a save button with a click event binding that invokes a new component method named save:

src/app/hero-detail.component.html (save)

<button (click)="save()">Save</button>

The save method persists hero name changes using the hero service update method and then navigates back to the previous view:

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

save(): void { this.heroService.update(this.hero) .then(() => this.goBack()); }

Hero service update method

The overall structure of the update method is similar to that of getHeroes, although we'll use an HTTP put to persist changes server-side:

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

private headers = new Headers({'Content-Type': 'application/json'}); update(hero: Hero): Promise<Hero> { const url = `${this.heroesUrl}/${hero.id}`; return this.http .put(url, JSON.stringify(hero), {headers: this.headers}) .toPromise() .then(() => hero) .catch(this.handleError); }

We identify which hero the server should update by encoding the hero id in the URL. The put body is the JSON string encoding of the hero, obtained by calling JSON.stringify. We identify the body content type (application/json) in the request header.

Refresh the browser and give it a try. Changes to hero names should now persist.

Add a hero

To add a new hero we need to know the hero's name. Let's use an input element for that, paired with an add button.

Insert the following into the heroes component HTML, first thing after the heading:

src/app/heroes.component.html (add)

<div> <label>Hero name:</label> <input #heroName /> <button (click)="add(heroName.value); heroName.value=''"> Add </button> </div>

In response to a click event, we call the component's click handler and then clear the input field so that it will be ready to use for another name.

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

add(name: string): void { name = name.trim(); if (!name) { return; } this.heroService.create(name) .then(hero => { this.heroes.push(hero); this.selectedHero = null; }); }

When the given name is non-blank, the handler delegates creation of the named hero to the hero service, and then adds the new hero to our array.

Finally, we implement the create method in the HeroService class.

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

create(name: string): Promise<Hero> { return this.http .post(this.heroesUrl, JSON.stringify({name: name}), {headers: this.headers}) .toPromise() .then(res => res.json().data) .catch(this.handleError); }

Refresh the browser and create some new heroes!

Delete a hero

Too many heroes? Let's add a delete button to each hero in the heroes view.

Add this button element to the heroes component HTML, right after the hero name in the repeated <li> tag:

<button class="delete" (click)="delete(hero); $event.stopPropagation()">x</button>

The <li> element should now look like this:

src/app/heroes.component.html (li-element)

<li *ngFor="let hero of heroes" (click)="onSelect(hero)" [class.selected]="hero === selectedHero"> <span class="badge">{{hero.id}}</span> <span>{{hero.name}}</span> <button class="delete" (click)="delete(hero); $event.stopPropagation()">x</button> </li>

In addition to calling the component's delete method, the delete button click handling code stops the propagation of the click event — we don't want the <li> click handler to be triggered because that would select the hero that we are going to delete!

The logic of the delete handler is a bit trickier:

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

delete(hero: Hero): void { this.heroService .delete(hero.id) .then(() => { this.heroes = this.heroes.filter(h => h !== hero); if (this.selectedHero === hero) { this.selectedHero = null; } }); }

Of course, we delegate hero deletion to the hero service, but the component is still responsible for updating the display: it removes the deleted hero from the array and resets the selected hero if necessary.

We want our delete button to be placed at the far right of the hero entry. This extra CSS accomplishes that:

src/app/heroes.component.css (additions)

button.delete { float:right; margin-top: 2px; margin-right: .8em; background-color: gray !important; color:white; }

Hero service delete method

The hero service's delete method uses the delete HTTP method to remove the hero from the server:

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

delete(id: number): Promise<void> { const url = `${this.heroesUrl}/${id}`; return this.http.delete(url, {headers: this.headers}) .toPromise() .then(() => null) .catch(this.handleError); }

Refresh the browser and try the new delete functionality.

Observables

Each Http service method returns an Observable of HTTP Response objects.

Our HeroService converts that Observable into a Promise and returns the promise to the caller. In this section we learn to return the Observable directly and discuss when and why that might be a good thing to do.

Background

An observable is a stream of events that we can process with array-like operators.

Angular core has basic support for observables. We developers augment that support with operators and extensions from the RxJS library. We'll see how shortly.

Recall that our HeroService quickly chained the toPromise operator to the Observable result of http.get. That operator converted the Observable into a Promise and we passed that promise back to the caller.

Converting to a promise is often a good choice. We typically ask http.get to fetch a single chunk of data. When we receive the data, we're done. A single result in the form of a promise is easy for the calling component to consume and it helps that promises are widely understood by JavaScript programmers.

But requests aren't always "one and done". We may start one request, then cancel it, and make a different request before the server has responded to the first request. Such a request-cancel-new-request sequence is difficult to implement with Promises. It's easy with Observables as we'll see.

Search-by-name

We're going to add a hero search feature to the Tour of Heroes. As the user types a name into a search box, we'll make repeated HTTP requests for heroes filtered by that name.

We start by creating HeroSearchService that sends search queries to our server's web api.

src/app/hero-search.service.ts

import { Injectable } from '@angular/core'; import { Http } from '@angular/http'; import { Observable } from 'rxjs/Observable'; import 'rxjs/add/operator/map'; import { Hero } from './hero'; @Injectable() export class HeroSearchService { constructor(private http: Http) {} search(term: string): Observable<Hero[]> { return this.http .get(`app/heroes/?name=${term}`) .map(response => response.json().data as Hero[]); } }

The http.get() call in HeroSearchService is similar to the one in the HeroService, although the URL now has a query string.

A more important difference: we no longer call toPromise. Instead we return the observable from the http.get, after chaining it to another RxJS operator, map, to extract heroes from the response data.

RxJS operator chaining makes response processing easy and readable. See the discuss below about operators.

HeroSearchComponent

Let's create a new HeroSearchComponent that calls this new HeroSearchService.

The component template is simple — just a text box and a list of matching search results.

src/app/hero-search.component.html

<div id="search-component"> <h4>Hero Search</h4> <input #searchBox id="search-box" (keyup)="search(searchBox.value)" /> <div> <div *ngFor="let hero of heroes | async" (click)="gotoDetail(hero)" class="search-result" > {{hero.name}} </div> </div> </div>

We'll also want to add styles for the new component.

src/app/hero-search.component.css

.search-result{ border-bottom: 1px solid gray; border-left: 1px solid gray; border-right: 1px solid gray; width:195px; height: 16px; padding: 5px; background-color: white; cursor: pointer; } .search-result:hover { color: #eee; background-color: #607D8B; } #search-box{ width: 200px; height: 20px; }

As the user types in the search box, a keyup event binding calls the component's search method with the new search box value.

The *ngFor repeats hero objects from the component's heroes property. No surprise there.

But, as we'll soon see, the heroes property is now an Observable of hero arrays, rather than just a hero array. The *ngFor can't do anything with an Observable until we flow it through the async pipe (AsyncPipe). The async pipe subscribes to the Observable and produces the array of heroes to *ngFor.

Time to create the HeroSearchComponent class and metadata.

src/app/hero-search.component.ts

import { Component, OnInit } from '@angular/core'; import { Router } from '@angular/router'; import { Observable } from 'rxjs/Observable'; import { Subject } from 'rxjs/Subject'; // Observable class extensions import 'rxjs/add/observable/of'; // Observable operators import 'rxjs/add/operator/catch'; import 'rxjs/add/operator/debounceTime'; import 'rxjs/add/operator/distinctUntilChanged'; import { HeroSearchService } from './hero-search.service'; import { Hero } from './hero'; @Component({ selector: 'hero-search', templateUrl: './hero-search.component.html', styleUrls: [ './hero-search.component.css' ], providers: [HeroSearchService] }) export class HeroSearchComponent implements OnInit { heroes: Observable<Hero[]>; private searchTerms = new Subject<string>(); constructor( private heroSearchService: HeroSearchService, private router: Router) {} // Push a search term into the observable stream. search(term: string): void { this.searchTerms.next(term); } ngOnInit(): void { this.heroes = this.searchTerms .debounceTime(300) // wait 300ms after each keystroke before considering the term .distinctUntilChanged() // ignore if next search term is same as previous .switchMap(term => term // switch to new observable each time the term changes // return the http search observable ? this.heroSearchService.search(term) // or the observable of empty heroes if there was no search term : Observable.of<Hero[]>([])) .catch(error => { // TODO: add real error handling console.log(error); return Observable.of<Hero[]>([]); }); } gotoDetail(hero: Hero): void { let link = ['/detail', hero.id]; this.router.navigate(link); } }

Search terms

Let's focus on the searchTerms:

private searchTerms = new Subject<string>(); // Push a search term into the observable stream. search(term: string): void { this.searchTerms.next(term); }

A Subject is a producer of an observable event stream; searchTerms produces an Observable of strings, the filter criteria for the name search.

Each call to search puts a new string into this subject's observable stream by calling next.

Initialize the heroes property (ngOnInit)

A Subject is also an Observable. We're going to turn the stream of search terms into a stream of Hero arrays and assign the result to the heroes property.

heroes: Observable<Hero[]>; ngOnInit(): void { this.heroes = this.searchTerms .debounceTime(300) // wait 300ms after each keystroke before considering the term .distinctUntilChanged() // ignore if next search term is same as previous .switchMap(term => term // switch to new observable each time the term changes // return the http search observable ? this.heroSearchService.search(term) // or the observable of empty heroes if there was no search term : Observable.of<Hero[]>([])) .catch(error => { // TODO: add real error handling console.log(error); return Observable.of<Hero[]>([]); }); }

If we passed every user keystroke directly to the HeroSearchService, we'd unleash a storm of HTTP requests. Bad idea. We don't want to tax our server resources and burn through our cellular network data plan.

Fortunately, we can chain Observable operators to the string Observable that reduce the request flow. We'll make fewer calls to the HeroSearchService and still get timely results. Here's how:

The switchMap operator (formerly known as "flatMapLatest") is very clever.

Every qualifying key event can trigger an http method call. Even with a 300ms pause between requests, we could have multiple HTTP requests in flight and they may not return in the order sent.

switchMap preserves the original request order while returning only the observable from the most recent http method call. Results from prior calls are canceled and discarded.

We also short-circuit the http method call and return an observable containing an empty array if the search text is empty.

Note that canceling the HeroSearchService observable won't actually abort a pending HTTP request until the service supports that feature, a topic for another day. We are content for now to discard unwanted results.

Import RxJS operators

Most RxJS operators are not included in Angular's base Observable implementation. The base implementation includes only what Angular itself requires.

If we want more RxJS features, we have to extend Observable by importing the libraries in which they are defined. Here are all the RxJS imports this component needs:

src/app/hero-search.component.ts (rxjs imports)

import { Observable } from 'rxjs/Observable'; import { Subject } from 'rxjs/Subject'; // Observable class extensions import 'rxjs/add/observable/of'; // Observable operators import 'rxjs/add/operator/catch'; import 'rxjs/add/operator/debounceTime'; import 'rxjs/add/operator/distinctUntilChanged';

The import 'rxjs/add/...' syntax may be unfamiliar. It's missing the usual list of symbols between the braces: {...}.

We don't need the operator symbols themselves. In each case, the mere act of importing the library loads and executes the library's script file which, in turn, adds the operator to the Observable class.

Add the search component to the dashboard

We add the hero search HTML element to the bottom of the DashboardComponent template.

src/app/dashboard.component.html

<h3>Top Heroes</h3> <div class="grid grid-pad"> <a *ngFor="let hero of heroes" [routerLink]="['/detail', hero.id]" class="col-1-4"> <div class="module hero"> <h4>{{hero.name}}</h4> </div> </a> </div> <hero-search></hero-search>

Finally, we import HeroSearchComponent from hero-search.component.ts and add it to the declarations array:

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

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

Run the app again, go to the Dashboard, and enter some text in the search box. At some point it might look like this.

Hero Search Component

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.ts
app.component.css
app.module.ts
app-routing.module.ts
dashboard.component.css
dashboard.component.html
dashboard.component.ts
hero.ts
hero-detail.component.css
hero-detail.component.html
hero-detail.component.ts
hero-search.component.html (new)
hero-search.component.css (new)
hero-search.component.ts (new)
hero-search.service.ts (new)
hero.service.ts
heroes.component.css
heroes.component.html
heroes.component.ts
in-memory-data.service.ts (new)
main.ts
index.html
styles.css
systemjs.config.js
tsconfig.json
node_modules ...
package.json

Home Stretch

We are at the end of our journey for now, but we have accomplished a lot.

Here are the files we added or changed in this chapter.

import { Component } from '@angular/core'; @Component({ selector: 'my-app', template: ` <h1>{{title}}</h1> <nav> <a routerLink="/dashboard" routerLinkActive="active">Dashboard</a> <a routerLink="/heroes" routerLinkActive="active">Heroes</a> </nav> <router-outlet></router-outlet> `, styleUrls: ['./app.component.css'] }) export class AppComponent { title = 'Tour of Heroes'; } import { NgModule } from '@angular/core'; import { BrowserModule } from '@angular/platform-browser'; import { FormsModule } from '@angular/forms'; import { HttpModule } from '@angular/http'; import { AppRoutingModule } from './app-routing.module'; // Imports for loading & configuring the in-memory web api import { InMemoryWebApiModule } from 'angular-in-memory-web-api'; import { InMemoryDataService } from './in-memory-data.service'; import { AppComponent } from './app.component'; import { DashboardComponent } from './dashboard.component'; import { HeroesComponent } from './heroes.component'; import { HeroDetailComponent } from './hero-detail.component'; import { HeroService } from './hero.service'; import { HeroSearchComponent } from './hero-search.component'; @NgModule({ imports: [ BrowserModule, FormsModule, HttpModule, InMemoryWebApiModule.forRoot(InMemoryDataService), AppRoutingModule ], declarations: [ AppComponent, DashboardComponent, HeroDetailComponent, HeroesComponent, HeroSearchComponent ], providers: [ HeroService ], bootstrap: [ AppComponent ] }) export class AppModule { } import { Component, OnInit } from '@angular/core'; import { Router } from '@angular/router'; import { Hero } from './hero'; import { HeroService } from './hero.service'; @Component({ selector: 'my-heroes', templateUrl: './heroes.component.html', styleUrls: [ './heroes.component.css' ] }) export class HeroesComponent implements OnInit { heroes: Hero[]; selectedHero: Hero; constructor( private heroService: HeroService, private router: Router) { } getHeroes(): void { this.heroService .getHeroes() .then(heroes => this.heroes = heroes); } add(name: string): void { name = name.trim(); if (!name) { return; } this.heroService.create(name) .then(hero => { this.heroes.push(hero); this.selectedHero = null; }); } delete(hero: Hero): void { this.heroService .delete(hero.id) .then(() => { this.heroes = this.heroes.filter(h => h !== hero); if (this.selectedHero === hero) { this.selectedHero = null; } }); } ngOnInit(): void { this.getHeroes(); } onSelect(hero: Hero): void { this.selectedHero = hero; } gotoDetail(): void { this.router.navigate(['/detail', this.selectedHero.id]); } } <h2>My Heroes</h2> <div> <label>Hero name:</label> <input #heroName /> <button (click)="add(heroName.value); heroName.value=''"> Add </button> </div> <ul class="heroes"> <li *ngFor="let hero of heroes" (click)="onSelect(hero)" [class.selected]="hero === selectedHero"> <span class="badge">{{hero.id}}</span> <span>{{hero.name}}</span> <button class="delete" (click)="delete(hero); $event.stopPropagation()">x</button> </li> </ul> <div *ngIf="selectedHero"> <h2> {{selectedHero.name | uppercase}} is my hero </h2> <button (click)="gotoDetail()">View Details</button> </div> .selected { background-color: #CFD8DC !important; color: white; } .heroes { margin: 0 0 2em 0; list-style-type: none; padding: 0; width: 15em; } .heroes li { cursor: pointer; position: relative; left: 0; background-color: #EEE; margin: .5em; padding: .3em 0; height: 1.6em; border-radius: 4px; } .heroes li:hover { color: #607D8B; background-color: #DDD; left: .1em; } .heroes li.selected:hover { background-color: #BBD8DC !important; color: white; } .heroes .text { position: relative; top: -3px; } .heroes .badge { display: inline-block; font-size: small; color: white; padding: 0.8em 0.7em 0 0.7em; background-color: #607D8B; line-height: 1em; position: relative; left: -1px; top: -4px; height: 1.8em; margin-right: .8em; border-radius: 4px 0 0 4px; } button { font-family: Arial; background-color: #eee; border: none; padding: 5px 10px; border-radius: 4px; cursor: pointer; cursor: hand; } button:hover { background-color: #cfd8dc; } button.delete { float:right; margin-top: 2px; margin-right: .8em; background-color: gray !important; color:white; } import 'rxjs/add/operator/switchMap'; import { Component, OnInit } from '@angular/core'; import { ActivatedRoute, Params } from '@angular/router'; import { Location } from '@angular/common'; import { Hero } from './hero'; import { HeroService } from './hero.service'; @Component({ selector: 'my-hero-detail', templateUrl: './hero-detail.component.html', styleUrls: [ './hero-detail.component.css' ] }) export class HeroDetailComponent implements OnInit { hero: Hero; constructor( private heroService: HeroService, private route: ActivatedRoute, private location: Location ) {} ngOnInit(): void { this.route.params .switchMap((params: Params) => this.heroService.getHero(+params['id'])) .subscribe(hero => this.hero = hero); } save(): void { this.heroService.update(this.hero) .then(() => this.goBack()); } goBack(): void { this.location.back(); } } <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> <button (click)="save()">Save</button> </div> import { Injectable } from '@angular/core'; import { Headers, Http } from '@angular/http'; import 'rxjs/add/operator/toPromise'; import { Hero } from './hero'; @Injectable() export class HeroService { private headers = new Headers({'Content-Type': 'application/json'}); private heroesUrl = 'api/heroes'; // URL to web api constructor(private http: Http) { } getHeroes(): Promise<Hero[]> { return this.http.get(this.heroesUrl) .toPromise() .then(response => response.json().data as Hero[]) .catch(this.handleError); } getHero(id: number): Promise<Hero> { const url = `${this.heroesUrl}/${id}`; return this.http.get(url) .toPromise() .then(response => response.json().data as Hero) .catch(this.handleError); } delete(id: number): Promise<void> { const url = `${this.heroesUrl}/${id}`; return this.http.delete(url, {headers: this.headers}) .toPromise() .then(() => null) .catch(this.handleError); } create(name: string): Promise<Hero> { return this.http .post(this.heroesUrl, JSON.stringify({name: name}), {headers: this.headers}) .toPromise() .then(res => res.json().data) .catch(this.handleError); } update(hero: Hero): Promise<Hero> { const url = `${this.heroesUrl}/${hero.id}`; return this.http .put(url, JSON.stringify(hero), {headers: this.headers}) .toPromise() .then(() => hero) .catch(this.handleError); } private handleError(error: any): Promise<any> { console.error('An error occurred', error); // for demo purposes only return Promise.reject(error.message || error); } } import { InMemoryDbService } from 'angular-in-memory-web-api'; export class InMemoryDataService implements InMemoryDbService { createDb() { let heroes = [ {id: 11, name: 'Mr. Nice'}, {id: 12, name: 'Narco'}, {id: 13, name: 'Bombasto'}, {id: 14, name: 'Celeritas'}, {id: 15, name: 'Magneta'}, {id: 16, name: 'RubberMan'}, {id: 17, name: 'Dynama'}, {id: 18, name: 'Dr IQ'}, {id: 19, name: 'Magma'}, {id: 20, name: 'Tornado'} ]; return {heroes}; } } import { Injectable } from '@angular/core'; import { Http } from '@angular/http'; import { Observable } from 'rxjs/Observable'; import 'rxjs/add/operator/map'; import { Hero } from './hero'; @Injectable() export class HeroSearchService { constructor(private http: Http) {} search(term: string): Observable<Hero[]> { return this.http .get(`app/heroes/?name=${term}`) .map(response => response.json().data as Hero[]); } } import { Component, OnInit } from '@angular/core'; import { Router } from '@angular/router'; import { Observable } from 'rxjs/Observable'; import { Subject } from 'rxjs/Subject'; // Observable class extensions import 'rxjs/add/observable/of'; // Observable operators import 'rxjs/add/operator/catch'; import 'rxjs/add/operator/debounceTime'; import 'rxjs/add/operator/distinctUntilChanged'; import { HeroSearchService } from './hero-search.service'; import { Hero } from './hero'; @Component({ selector: 'hero-search', templateUrl: './hero-search.component.html', styleUrls: [ './hero-search.component.css' ], providers: [HeroSearchService] }) export class HeroSearchComponent implements OnInit { heroes: Observable<Hero[]>; private searchTerms = new Subject<string>(); constructor( private heroSearchService: HeroSearchService, private router: Router) {} // Push a search term into the observable stream. search(term: string): void { this.searchTerms.next(term); } ngOnInit(): void { this.heroes = this.searchTerms .debounceTime(300) // wait 300ms after each keystroke before considering the term .distinctUntilChanged() // ignore if next search term is same as previous .switchMap(term => term // switch to new observable each time the term changes // return the http search observable ? this.heroSearchService.search(term) // or the observable of empty heroes if there was no search term : Observable.of<Hero[]>([])) .catch(error => { // TODO: add real error handling console.log(error); return Observable.of<Hero[]>([]); }); } gotoDetail(hero: Hero): void { let link = ['/detail', hero.id]; this.router.navigate(link); } } <div id="search-component"> <h4>Hero Search</h4> <input #searchBox id="search-box" (keyup)="search(searchBox.value)" /> <div> <div *ngFor="let hero of heroes | async" (click)="gotoDetail(hero)" class="search-result" > {{hero.name}} </div> </div> </div> .search-result{ border-bottom: 1px solid gray; border-left: 1px solid gray; border-right: 1px solid gray; width:195px; height: 16px; padding: 5px; background-color: white; cursor: pointer; } .search-result:hover { color: #eee; background-color: #607D8B; } #search-box{ width: 200px; height: 20px; }

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