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docs: edit copy of getting started step 3 (#32820) 

PR Close #32820
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Kapunahele Wong 2019-09-20 16:22:58 -04:00 committed by Andrew Kushnir
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3
aio/content/examples/getting-started/src/app/app.module.ts
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@ -1,8 +1,8 @@
// #docplaster
// #docregion http-client-module-import, http-client-module
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { RouterModule } from '@angular/router';
// #docregion http-client-module-import
import { HttpClientModule } from '@angular/common/http';
// #enddocregion http-client-module-import
import { ReactiveFormsModule } from '@angular/forms';
@ -12,7 +12,6 @@ import { TopBarComponent } from './top-bar/top-bar.component';
import { ProductListComponent } from './product-list/product-list.component';
import { ProductAlertsComponent } from './product-alerts/product-alerts.component';
import { ProductDetailsComponent } from './product-details/product-details.component';
// #enddocregion http-client-module
import { CartComponent } from './cart/cart.component';
import { ShippingComponent } from './shipping/shipping.component';

202
aio/content/start/data.md
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@ -1,31 +1,36 @@
# Managing Data
At the end of [Routing](start/routing "Getting Started: Routing"), the online store application has a product catalog with two views: a product list and product details.
Users can click on a product name from the list to see details in a new view, with a distinct URL (route).
Users can click on a product name from the list to see details in a new view, with a distinct URL, or route.
In this section, you'll create the shopping cart. You'll:
* Update the product details page to include a "Buy" button, which adds the current product to a list of products managed by a cart service.
* Add a cart component, which displays the items you added to your cart.
This page guides you through creating the shopping cart in three phases:
* Update the product details page to include a "Buy" button, which adds the current product to a list of products that a cart service manages.
* Add a cart component, which displays the items in the cart.
* Add a shipping component, which retrieves shipping prices for the items in the cart by using Angular's `HttpClient` to retrieve shipping data from a `.json` file.
{@a services}
## Services
Services are an integral part of Angular applications. In Angular, a service is an instance of a class that can be made available to any part of your application using Angular's [dependency injection system](guide/glossary#dependency-injection-di "dependency injection definition").
Services are an integral part of Angular applications. In Angular, a service is an instance of a class that you can make available to any part of your application using Angular's [dependency injection system](guide/glossary#dependency-injection-di "dependency injection definition").
Services are the place where you share data between parts of your application. For the online store, the cart service is where you store your cart data and methods.
{@a create-cart-service}
## Create the shopping cart service
Up to this point, users can view product information, and simulate sharing and being notified about product changes. They cannot, however, buy products.
Up to this point, users can view product information, and
simulate sharing and being notified about product changes.
They cannot, however, buy products.
In this section, you'll add a "Buy" button to the product details page.
You'll also set up a cart service to store information about products in the cart.
In this section, you add a "Buy" button to the product
details page and set up a cart service to store information
about products in the cart.
<div class="alert is-helpful">
Later, in the [Forms](start/forms "Getting Started: Forms") part of this tutorial, this cart service also will be accessed from the page where the user checks out.
Later, the [Forms](start/forms "Getting Started: Forms") part of
this tutorial guides you through accessing this cart service
from the page where the user checks out.
</div>
@ -38,47 +43,40 @@ Later, in the [Forms](start/forms "Getting Started: Forms") part of this tutoria
<code-example header="src/app/cart.service.ts" path="getting-started/src/app/cart.service.1.ts"></code-example>
1. If the generated `@Injectable()` decorator does not include the `{ providedIn: 'root' }` statement, then insert it as shown above.
1. StackBlitz might generate the `@Injectable()` decorator without the `{ providedIn: 'root' }` statement as above. Instead, the generator provides the cart service in `app.module.ts` by default. For the purposes
of this tutorial, either way works. The `@Injectable()` `{ providedIn: 'root' }` syntax allows [tree shaking](/guide/dependency-injection-providers#tree-shakable-providers), which is beyond the scope of this guide.
1. In the `CartService` class, define an `items` property to store the list (array) of the current products in the cart.
1. In the `CartService` class, define an `items` property to store the array of the current products in the cart.
<code-example path="getting-started/src/app/cart.service.ts" region="props"></code-example>
<code-example path="getting-started/src/app/cart.service.ts" header="src/app/cart.service.ts" region="props"></code-example>
1. Define methods to add items to the cart, return cart items, and clear the cart items:
<code-example path="getting-started/src/app/cart.service.ts" region="methods"></code-example>
<code-example path="getting-started/src/app/cart.service.ts" header="src/app/cart.service.ts" region="methods"></code-example>
<!--
To check: StackBlitz includes the constructor. If it's important (and not obvious) that the methods be below the constructor, then we should show it or say something.
-->
<!--
* The `addToCart()` method appends a product to an array of `items`.
* The `getItems()` method collects the items added to the cart and returns each item with its associated quantity.
* The `getItems()` method collects the items users add to the cart and returns each item with its associated quantity.
* The `clearCart()` method returns an empty array of items.
-->
{@a product-details-use-cart-service}
### Use the cart service
In this section, you'll update the product details component to use the cart service.
You'll add a "Buy" button to the product details view.
When the "Buy" button is clicked, you'll use the cart service to add the current product to the cart.
This section walks you through using the cart service to add a product to the cart with a "Buy" button.
1. Open `product-details.component.ts`.
1. Set up the component to be able to use the cart service.
1. Configure the component to use the cart service.
1. Import the cart service.
<code-example header="src/app/product-details/product-details.component.ts" path="getting-started/src/app/product-details/product-details.component.ts" region="cart-service">
</code-example>
1. Inject the cart service.
1. Inject the cart service by adding it to the `constructor()`.
<code-example path="getting-started/src/app/product-details/product-details.component.ts" region="inject-cart-service">
<code-example path="getting-started/src/app/product-details/product-details.component.ts" header="src/app/product-details/product-details.component.ts" region="inject-cart-service">
</code-example>
<!--
@ -87,14 +85,14 @@ When the "Buy" button is clicked, you'll use the cart service to add the current
1. Define the `addToCart()` method, which adds the current product to the cart.
The `addToCart()` method:
* Receives the current `product`
* Uses the cart service's `#addToCart()` method to add the product to the cart
* Displays a message that the product has been added to the cart
The `addToCart()` method does the following three things:
* Receives the current `product`.
* Uses the cart service's `addToCart()` method to add the product the cart.
* Displays a message that you've added a product to the cart.
<code-example path="getting-started/src/app/product-details/product-details.component.ts" region="add-to-cart"></code-example>
<code-example path="getting-started/src/app/product-details/product-details.component.ts" header="src/app/product-details/product-details.component.ts" region="add-to-cart"></code-example>
1. Update the product details template to have a "Buy" button that adds the current product to the cart.
1. Update the product details template with a "Buy" button that adds the current product to the cart.
1. Open `product-details.component.html`.
@ -109,7 +107,7 @@ When the "Buy" button is clicked, you'll use the cart service to add the current
<img src='generated/images/guide/start/product-details-buy.png' alt="Display details for selected product with a Buy button">
</div>
1. Click the "Buy" button. The product is added to the stored list of items in the cart, and a message is displayed.
1. Click the "Buy" button to add the product to the stored list of items in the cart and display a confirmation message.
<div class="lightbox">
<img src='generated/images/guide/start/buy-alert.png' alt="Display details for selected product with a Buy button">
@ -120,14 +118,14 @@ When the "Buy" button is clicked, you'll use the cart service to add the current
At this point, users can put items in the cart by clicking "Buy", but they can't yet see their cart.
We'll create the cart page in two steps:
Create the cart page in two steps:
1. Create a cart component and set up routing to the new component. At this point, the cart page will only have default text.
1. Create a cart component and configure routing to the new component. At this point, the cart page will only have default text.
1. Display the cart items.
### Set up the component
To create the cart page, you begin by following the same steps you did to create the product details component and to set up routing for the new component.
To create the cart page, begin by following the same steps you did to create the product details component and configure routing for the new component.
1. Generate a cart component, named `cart`.
@ -137,18 +135,18 @@ We'll create the cart page in two steps:
1. Add routing (a URL pattern) for the cart component.
Reminder: Open `app.module.ts` and add a route for the component `CartComponent`, with a `path` of `cart`:
Open `app.module.ts` and add a route for the component `CartComponent`, with a `path` of `cart`:
<code-example header="src/app/app.module.ts" path="getting-started/src/app/app.module.ts" region="cart-route">
</code-example>
<!--
To do: Can we shorten the example code to remove the extra at the bottom?
-->
1. To see the new cart component, click the "Checkout" button. You can see the "cart works!" default text, and the URL has the pattern `https://getting-started.stackblitz.io/cart`, where `getting-started.stackblitz.io` may be different for your StackBlitz project.
(Note: The "Checkout" button that we provided in the top-bar component was already configured with a `routerLink` for `/cart`.)
<div class="alert is-helpful">
The starter code for the "Checkout" button already includes a `routerLink` for `/cart` the top-bar component.
</div>
<div class="lightbox">
<img src='generated/images/guide/start/cart-works.png' alt="Display cart page before customizing">
@ -157,41 +155,41 @@ We'll create the cart page in two steps:
### Display the cart items
Services can be used to share data across components:
You can use services to share data across components:
* The product details component already uses the cart service (`CartService`) to add products to the cart.
* In this section, you'll update the cart component to use the cart service to display the products in the cart.
* The product details component already uses the cart service to add products to the cart.
* This section shows you how to use the cart service to display the products in the cart.
1. Open `cart.component.ts`.
1. Set up the component to be able to use the cart service. (This is the same way you set up the product details component to use the cart service, above.)
1. Configure the component to use the cart service.
1. Import the `CartService` from the `cart.service.ts` file.
<code-example header="src/app/cart/cart.component.ts" path="getting-started/src/app/cart/cart.component.2.ts" region="imports">
</code-example>
1. Inject the `CartService` to manage cart information.
1. Inject the `CartService` so that the cart component can use it.
<code-example path="getting-started/src/app/cart/cart.component.2.ts" region="inject-cart">
<code-example path="getting-started/src/app/cart/cart.component.2.ts" header="src/app/cart/cart.component.ts" region="inject-cart">
</code-example>
1. Define the `items` property to store the products in the cart.
<code-example path="getting-started/src/app/cart/cart.component.2.ts" region="items">
<code-example path="getting-started/src/app/cart/cart.component.2.ts" header="src/app/cart/cart.component.ts" region="items">
</code-example>
1. Set the items using the cart service's `getItems()` method. (You defined this method [when you generated `cart.service.ts`](#generate-cart-service).)
1. Set the items using the cart service's `getItems()` method. Recall that you defined this method [when you generated `cart.service.ts`](#generate-cart-service).
The resulting `CartComponent` class should look like this:
The resulting `CartComponent` class is as follows:
<code-example path="getting-started/src/app/cart/cart.component.3.ts" region="props-services">
<code-example path="getting-started/src/app/cart/cart.component.3.ts" header="src/app/cart/cart.component.ts" region="props-services">
</code-example>
1. Update the template with a header ("Cart"), and use a `<div>` with an `*ngFor` to display each of the cart items with its name and price.
1. Update the template with a header, and use a `<div>` with an `*ngFor` to display each of the cart items with its name and price.
The resulting `CartComponent` template should look like this:
The resulting `CartComponent` template is as follows:
<code-example header="src/app/cart/cart.component.html" path="getting-started/src/app/cart/cart.component.2.html" region="prices">
</code-example>
@ -202,7 +200,9 @@ Services can be used to share data across components:
1. Click on a product name to display its details.
1. Click "Buy" to add the product to the cart.
1. Click "Checkout" to see the cart.
1. To add another product, click "My Store" to return to the product list. Repeat the steps above.
1. To add another product, click "My Store" to return to the product list.
Repeat to add more items to the cart.
<div class="lightbox">
<img src='generated/images/guide/start/cart-page-full.png' alt="Cart page with products added">
@ -211,72 +211,59 @@ Services can be used to share data across components:
<div class="alert is-helpful">
StackBlitz tip: Any time the preview refreshes, the cart is cleared. If you make changes to the app, the page refreshes, and you'll need to buy products again to populate the cart.
StackBlitz tip: Any time the preview refreshes, the cart is cleared. If you make changes to the app, the page refreshes, so you'll need to buy products again to populate the cart.
</div>
<!--
To do: New screen shot. No shipping prices link yet. Show a few products in the cart.
-->
<div class="alert is-helpful">
Learn more: See [Introduction to Services and Dependency Injection](guide/architecture-services "Architecture > Intro to Services and DI") for more information about services.
For more information about services, see [Introduction to Services and Dependency Injection](guide/architecture-services "Architecture > Intro to Services and DI").
</div>
## Retrieve shipping prices
<!-- Accessing data with the HTTP client -->
Data returned from servers often takes the form of a stream.
Streams are useful because they make it easy to transform the data that is returned, and to make modifications to the way data is requested.
The Angular HTTP client (`HttpClient`) is a built-in way to fetch data from external APIs and provide them to your application as a stream.
Servers often return data in the form of a stream.
Streams are useful because they make it easy to transform the returned data and make modifications to the way you request that data.
The Angular HTTP client, `HttpClient`, is a built-in way to fetch data from external APIs and provide them to your app as a stream.
In this section, you'll use the HTTP client to retrieve shipping prices from an external file.
This section shows you how to use the HTTP client to retrieve shipping prices from an external file.
### Predefined shipping data
For the purpose of this Getting Started guide, we have provided shipping data in `assets/shipping.json`.
You'll use this data to add shipping prices for items in the cart.
The app StackBlitz generates for this guide comes with predefined shipping data in `assets/shipping.json`.
Use this data to add shipping prices for items in the cart.
<code-example header="src/assets/shipping.json" path="getting-started/src/assets/shipping.json">
</code-example>
### Enable HttpClient for app
### Use `HttpClient` in the `AppModule`
Before you can use Angular's HTTP client, you must set up your app to use `HttpClientModule`.
Before you can use Angular's HTTP client, you must configure your app to use `HttpClientModule`.
Angular's `HttpClientModule` registers the providers needed to use a single instance of the `HttpClient` service throughout your app.
The `HttpClient` service is what you inject into your services to fetch data and interact with external APIs and resources.
Angular's `HttpClientModule` registers the providers your app needs to use a single instance of the `HttpClient` service throughout your app.
1. Open `app.module.ts`.
This file contains imports and functionality that is available to the entire app.
1. Import `HttpClientModule` from the `@angular/common/http` package.
1. Import `HttpClientModule` from the `@angular/common/http` package at the top of the file with the other imports. As there are a number of other imports, this code snippet omits them for brevity. Be sure to leave the existing imports in place.
<code-example header="src/app/app.module.ts" path="getting-started/src/app/app.module.ts" region="http-client-module-import">
</code-example>
1. Add `HttpClientModule` to the `imports` array of the app module (`@NgModule`).
1. Add `HttpClientModule` to the `AppModule` `@NgModule()` `imports` array to register Angular's `HttpClient` providers globally.
This registers Angular's `HttpClient` providers globally.
<code-example path="getting-started/src/app/app.module.ts" region="http-client-module">
<code-example path="getting-started/src/app/app.module.ts" header="src/app/app.module.ts" region="http-client-module">
</code-example>
<!--
To do: Should ReactiveFormsModule already be here? Currently, it is in the starter stackblitz, so this doc assumes it is already included and not added in the forms section.
-->
### Use `HttpClient` in the cart service
<!--
To do: Should ReactiveFormsModule already be here?
-->
Now that the `AppModule` imports the `HttpClientModule`, the next step is to inject the `HttpClient` service into your service so your app can fetch data and interact with external APIs and resources.
### Enable HttpClient for cart service
1. Open `cart.service.ts`.
@ -285,37 +272,34 @@ To do: Should ReactiveFormsModule already be here?
<code-example header="src/app/cart.service.ts" path="getting-started/src/app/cart.service.ts" region="import-http">
</code-example>
1. Inject `HttpClient` into the constructor of the `CartService` component class:
1. Inject `HttpClient` into the `CartService` constructor:
<code-example path="getting-started/src/app/cart.service.ts" region="inject-http">
<code-example path="getting-started/src/app/cart.service.ts" header="src/app/cart.service.ts" region="inject-http">
</code-example>
### Define the get() method
### Define the `get()` method
As you've seen, multiple components can leverage the same service.
Later in this tutorial, the shipping component will use the cart service to retrieve shipping data via HTTP from the `shipping.json` file.
Here you'll define the `get()` method that will be used.
Multiple components can leverage the same service.
Later in this tutorial, the shipping component uses the cart service to retrieve shipping data via HTTP from the `shipping.json` file.
First, define a `get()` method.
1. Continue working in `cart.service.ts`.
1. Below the `clearCart()` method, define a new `getShippingPrices()` method that uses the `HttpClient#get()` method to retrieve the shipping data (types and prices).
1. Below the `clearCart()` method, define a new `getShippingPrices()` method that uses the `HttpClient` `get()` method to retrieve the shipping data.
<code-example header="src/app/cart.service.ts" path="getting-started/src/app/cart.service.ts" region="get-shipping"></code-example>
<div class="alert is-helpful">
Learn more: See the [HttpClient guide](guide/http "HttpClient guide") for more information about Angular's `HttpClient`.
For more information about Angular's `HttpClient`, see [HttpClient](guide/http "HttpClient guide").
</div>
## Define the shipping page
Now that your app can retrieve shipping data, you'll create a shipping component and associated template.
Now that your app can retrieve shipping data, create a shipping component and template.
1. Generate a new component named `shipping`.
@ -327,7 +311,7 @@ Now that your app can retrieve shipping data, you'll create a shipping component
<code-example header="src/app/app.module.ts" path="getting-started/src/app/app.module.ts" region="shipping-route"></code-example>
The new shipping component isn't hooked into any other component yet, but you can see it in the preview pane by entering the URL specified by its route. The URL has the pattern: `https://getting-started.stackblitz.io/shipping` where the `getting-started.stackblitz.io` part may be different for your StackBlitz project.
There's no link to the new shipping component yet, but you can see its template in the preview pane by entering the URL its route specifies. The URL has the pattern: `https://getting-started.stackblitz.io/shipping` where the `getting-started.stackblitz.io` part may be different for your StackBlitz project.
1. Modify the shipping component so it uses the cart service to retrieve shipping data via HTTP from the `shipping.json` file.
@ -337,23 +321,21 @@ Now that your app can retrieve shipping data, you'll create a shipping component
1. Define a `shippingCosts` property.
<code-example path="getting-started/src/app/shipping/shipping.component.ts" region="props"></code-example>
<code-example path="getting-started/src/app/shipping/shipping.component.ts" header="src/app/shipping/shipping.component.ts" region="props"></code-example>
1. Inject the cart service into the `ShippingComponent` class:
1. Inject the cart service in the `ShippingComponent` constructor:
<code-example path="getting-started/src/app/shipping/shipping.component.ts" region="inject-cart-service"></code-example>
<code-example path="getting-started/src/app/shipping/shipping.component.ts" header="src/app/shipping/shipping.component.ts" region="inject-cart-service"></code-example>
1. Set the `shippingCosts` property using the `getShippingPrices()` method from cart service.
1. Set the `shippingCosts` property using the `getShippingPrices()` method from the cart service.
<code-example path="getting-started/src/app/shipping/shipping.component.ts" region="ctor"></code-example>
<code-example path="getting-started/src/app/shipping/shipping.component.ts" header="src/app/shipping/shipping.component.ts" region="ctor"></code-example>
1. Update the shipping component's template to display the shipping types and prices using async pipe:
1. Update the shipping component's template to display the shipping types and prices using the `async` pipe:
<code-example header="src/app/shipping/shipping.component.html" path="getting-started/src/app/shipping/shipping.component.html"></code-example>
<!--
To decide: Should we describe async pipe
-->
The `async` pipe returns the latest value from a stream of data and continues to do so for the life of a given component. When Angular destroys that component, the `async` pipe automatically stops. For detailed information about the `async` pipe, see the [AsyncPipe API documentation](/api/common/AsyncPipe).
1. Add a link from the cart page to the shipping page:
@ -361,7 +343,7 @@ Now that your app can retrieve shipping data, you'll create a shipping component
1. Test your shipping prices feature:
Click on the "Checkout" button to see the updated cart. (Remember that changing the app causes the preview to refresh, which empties the cart.)
Click the "Checkout" button to see the updated cart. Remember that changing the app causes the preview to refresh, which empties the cart.
<div class="lightbox">
<img src='generated/images/guide/start/cart-empty-with-shipping-prices.png' alt="Cart with link to shipping prices">
@ -376,10 +358,8 @@ Now that your app can retrieve shipping data, you'll create a shipping component
## Next steps
Congratulations! You have an online store application with a product catalog and shopping cart. You also have the ability to look up and display shipping prices.
Congratulations! You have an online store application with a product catalog and shopping cart. You can also look up and display shipping prices.
To continue exploring Angular, choose either of the following options:
* [Continue to the "Forms" section](start/forms "Getting Started: Forms") to finish the app by adding the shopping cart page and a form-based checkout feature. You'll create a form to collect user information as part of checkout.
* [Continue to the "Forms" section](start/forms "Getting Started: Forms") to finish the app by adding the shopping cart page and a checkout form.
* [Skip ahead to the "Deployment" section](start/deployment "Getting Started: Deployment") to move to local development, or deploy your app to Firebase or your own server.