229 lines
6.8 KiB
Markdown
229 lines
6.8 KiB
Markdown
@title
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The Hero Editor
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@intro
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We build a simple hero editor.
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@description
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## Setup to develop locally
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Real application development takes place in a local development environment like your machine.
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Follow the [setup](guide/setup) instructions for creating a new project
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named <ngio-ex path="angular-tour-of-heroes"></ngio-ex>
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after which the file structure should look like this:
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<aio-filetree>
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<aio-folder>
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angular-tour-of-heroes
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<aio-folder>
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src
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<aio-folder>
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app
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<aio-file>
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app.component.ts
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</aio-file>
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<aio-file>
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app.module.ts
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</aio-file>
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</aio-folder>
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<aio-file>
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main.ts
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</aio-file>
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<aio-file>
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index.html
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</aio-file>
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<aio-file>
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styles.css
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</aio-file>
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<aio-file>
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systemjs.config.js
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</aio-file>
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<aio-file>
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tsconfig.json
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</aio-file>
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</aio-folder>
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<aio-file>
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node_modules ...
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</aio-file>
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<aio-file>
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package.json
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</aio-file>
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</aio-folder>
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</aio-filetree>
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When we're done with this first episode, the app runs like this <live-example></live-example>.
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## Keep the app transpiling and running
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We want to start the TypeScript compiler, have it watch for changes, and start our server.
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Do this by entering the following command in the terminal window.
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<code-example language="sh" class="code-shell">
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npm start
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</code-example>
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This command runs the compiler in watch mode, starts the server, launches the app in a browser,
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and keeps the app running while we continue to build the Tour of Heroes.
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## Show our Hero
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We want to display Hero data in our app
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Update the `AppComponent` so it has two properties: a `title` property for the application name and a `hero` property
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for a hero named "Windstorm".
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{@example 'toh-1/ts-snippets/app.component.snippets.pt1.ts' region='app-component-1'}
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Now update the template in the `@Component` decoration with data bindings to these new properties.
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{@example 'toh-1/ts-snippets/app.component.snippets.pt1.ts' region='show-hero'}
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The browser should refresh and display our title and hero.
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The double curly braces tell our app to read the `title` and `hero` properties from the component and render them.
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This is the "interpolation" form of one-way data binding.
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Learn more about interpolation in the [Displaying Data chapter](guide/displaying-data).### Hero object
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At the moment, our hero is just a name. Our hero needs more properties.
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Let's convert the `hero` from a literal string to a class.
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Create a `Hero` class with `id` and `name` properties.
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For now put this near the top of the `app.component.ts` file, just below the import statement.
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{@example 'toh-1/ts/src/app/app.component.ts' region='hero-class-1'}
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Now that we have a `Hero` class, let’s refactor our component’s `hero` property to be of type `Hero`.
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Then initialize it with an id of `1` and the name, "Windstorm".
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{@example 'toh-1/ts/src/app/app.component.ts' region='hero-property-1'}
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Because we changed the hero from a string to an object,
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we update the binding in the template to refer to the hero’s `name` property.
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{@example 'toh-1/ts-snippets/app.component.snippets.pt1.ts' region='show-hero-2'}
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The browser refreshes and continues to display our hero’s name.
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### Adding more HTML
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Displaying a name is good, but we want to see all of our hero’s properties.
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We’ll add a `<div>` for our hero’s `id` property and another `<div>` for our hero’s `name`.
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{@example 'toh-1/ts-snippets/app.component.snippets.pt1.ts' region='show-hero-properties'}
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Uh oh, our template string is getting long. We better take care of that to avoid the risk of making a typo in the template.
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### Multi-line template strings
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We could make a more readable template with string concatenation
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but that gets ugly fast, it is harder to read, and
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it is easy to make a spelling error. Instead,
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let’s take advantage of the template strings feature
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in ES2015 and TypeScript to maintain our sanity.
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Change the quotes around the template to back-ticks and
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put the `<h1>`, `<h2>` and `<div>` elements on their own lines.
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{@example 'toh-1/ts-snippets/app.component.snippets.pt1.ts' region='multi-line-strings'}
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## Editing Our Hero
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We want to be able to edit the hero name in a textbox.
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Refactor the hero name `<label>` with `<label>` and `<input>` elements as shown below:
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{@example 'toh-1/ts-snippets/app.component.snippets.pt1.ts' region='editing-Hero'}
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We see in the browser that the hero’s name does appear in the `<input>` textbox.
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But something doesn’t feel right.
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When we change the name, we notice that our change
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is not reflected in the `<h2>`. We won't get the desired behavior
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with a one-way binding to `<input>`.
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### Two-Way Binding
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We intend to display the name of the hero in the `<input>`, change it,
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and see those changes wherever we bind to the hero’s name.
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In short, we want two-way data binding.
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Before we can use two-way data binding for **form inputs**, we need to import the `FormsModule`
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package in our Angular module. We add it to the `NgModule` decorator's `imports` array. This array contains the list
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of external modules used by our application.
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Now we have included the forms package which includes `ngModel`.
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{@example 'toh-1/ts/src/app/app.module.ts'}
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Learn more about the `FormsModule` and `ngModel` in the
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[Forms](guide/forms) and
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[Template Syntax](guide/template-syntax) chapters.
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Let’s update the template to use the **`ngModel`** built-in directive for two-way binding.
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Replace the `<input>` with the following HTML
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<code-example language="html">
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<input [(ngModel)]="hero.name" placeholder="name">
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</code-example>
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The browser refreshes. We see our hero again. We can edit the hero’s name and
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see the changes reflected immediately in the `<h2>`.
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## The Road We’ve Travelled
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Let’s take stock of what we’ve built.
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* Our Tour of Heroes uses the double curly braces of interpolation (a kind of one-way data binding)
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to display the application title and properties of a `Hero` object.
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* We wrote a multi-line template using ES2015’s template strings to make our template readable.
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* We can both display and change the hero’s name after adding a two-way data binding to the `<input>` element
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using the built-in `ngModel` directive.
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* The `ngModel` directive also propagates changes to every other binding of the `hero.name`.
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Run the <live-example></live-example> for this part.
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Here's the complete `app.component.ts` as it stands now:
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{@example 'toh-1/ts/src/app/app.component.ts' region='pt1'}
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## The Road Ahead
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Our Tour of Heroes only displays one hero and we really want to display a list of heroes.
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We also want to allow the user to select a hero and display their details.
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We’ll learn more about how to retrieve lists, bind them to the
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template, and allow a user to select a hero in the
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[next tutorial chapter](tutorial/toh-pt2). |