angular-cn/public/docs/ts/latest/tutorial/toh-pt1.jade

include ../_util-fns

:marked
  ## Setup to develop locally
  Real application development takes place in a local development environment like your machine.
  
  Follow the [setup](../guide/setup.html) instructions for creating a new project
  named <ngio-ex path="angular-tour-of-heroes"></ngio-ex>
  after which the file structure should look like this:

.filetree
  .file angular-tour-of-heroes
  .children
    .file src
    .children
      .file app
      .children
        .file app.component.ts
        .file app.module.ts
      .file main.ts
      .file index.html
      .file styles.css
      .file systemjs.config.js
      .file tsconfig.json
    .file node_modules ... 
    .file package.json
:marked
  When we're done with this first episode, the app runs like this <live-example></live-example>.

  ## Keep the app transpiling and running
  We want to start the TypeScript compiler, have it watch for changes, and start our server. 
  Do this by entering the following command in the terminal window.


code-example(language="sh" class="code-shell").
  npm start

:marked
  This command runs the compiler in watch mode, starts the server, launches the app in a browser,
  and keeps the app running while we continue to build the Tour of Heroes.

.l-main-section
  :marked
    ## Show our Hero
    We want to display Hero data in our app

    Update the `AppComponent` so it has two properties: &nbsp; a `title` property for the application name and a `hero` property
    for a hero named "Windstorm".

  +makeExample('toh-1/ts-snippets/app.component.snippets.pt1.ts', 'app-component-1', 'src/app/app.component.ts (AppComponent class)')(format=".")

  :marked
    Now update the template in the `@Component` decoration with data bindings to these new properties.

  +makeExample('toh-1/ts-snippets/app.component.snippets.pt1.ts', 'show-hero')

  :marked
    The browser should refresh and display our title and hero.

    The double curly braces tell our app to read the `title` and `hero` properties from the component and render them.
    This is the "interpolation" form of one-way data binding.
.l-sub-section
  :marked
    Learn more about interpolation in the [Displaying Data chapter](../guide/displaying-data.html).
:marked
  ### Hero object

  At the moment, our hero is just a name.  Our hero needs more properties.
  Let's convert the `hero` from a literal string to a class.

  Create a `Hero` class with `id` and `name` properties.
  For now put this near the top of the `app.component.ts` file, just below the import statement.

+makeExample('toh-1/ts/src/app/app.component.ts', 'hero-class-1', 'src/app/app.component.ts (Hero class)')(format=".")

:marked
  Now that we have a `Hero` class, let’s refactor our component’s `hero` property to be of type `Hero`.
  Then initialize it with an id of `1` and the name, "Windstorm".

+makeExample('toh-1/ts/src/app/app.component.ts', 'hero-property-1', 'src/app/app.component.ts (hero property)')(format=".")

:marked
  Because we changed the hero from a string to an object,
  we update the binding in the template to refer to the hero’s `name` property.

+makeExample('toh-1/ts-snippets/app.component.snippets.pt1.ts', 'show-hero-2')
:marked
  The browser refreshes and continues to display our hero’s name.

  ### Adding more HTML
  Displaying a name is good, but we want to see all of our hero’s properties.
  We’ll add a `<div>` for our hero’s `id` property and another `<div>` for our hero’s `name`.

+makeExample('toh-1/ts-snippets/app.component.snippets.pt1.ts', 'show-hero-properties')
:marked
  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.

  ### Multi-line template strings

  We could make a more readable template with string concatenation
  but that gets ugly fast, it is harder to read, and
  it is easy to make a spelling error. Instead,
  let’s take advantage of the template strings feature
  in ES2015 and TypeScript to maintain our sanity.

  Change the quotes around the template to back-ticks and
  put the `<h1>`, `<h2>` and `<div>` elements on their own lines.

+makeExample('toh-1/ts-snippets/app.component.snippets.pt1.ts', 'multi-line-strings', 'src/app/app.component.ts (AppComponent\'s template)')

  .callout.is-important
    header A back-tick is not a single quote
    :marked
      **Be careful!** A back-tick (`) looks a lot like a single quote (').
      It's actually a completely different character.
      Back-ticks can do more than demarcate a string.
      Here we use them in a limited way to spread the template over multiple lines.
      Everything between the back-ticks at the beginning and end of the template
      is part of a single template string.

.l-main-section
:marked
  ## Editing Our Hero

  We want to be able to edit the hero name in a textbox.

  Refactor the hero name `<label>` with `<label>` and `<input>` elements as shown below:

+makeExample('toh-1/ts-snippets/app.component.snippets.pt1.ts', 'editing-Hero', 'src/appapp.component.ts (input element)')
:marked
  We see in the browser that the hero’s name does appear in the `<input>` textbox.
  But something doesn’t feel right.
  When we change the name, we notice that our change
  is not reflected in the `<h2>`. We won't get the desired behavior
  with a one-way binding to `<input>`.

  ### Two-Way Binding

  We intend to display the name of the hero in the `<input>`, change it,
  and see those changes wherever we bind to the hero’s name.
  In short, we want two-way data binding.

  Before we can use two-way data binding for **form inputs**, we need to import the `FormsModule`
  package in our Angular module. We add it to the `NgModule` decorator's `imports` array. This array contains the list
  of external modules used by our application.
  Now we have included the forms package which includes `ngModel`.

+makeExample('toh-1/ts/src/app/app.module.ts', '', 'src/app/app.module.ts (FormsModule import)')

.l-sub-section
  :marked
    Learn more about the `FormsModule` and `ngModel` in the
    [Forms](../guide/forms.html#ngModel) and
    [Template Syntax](../guide/template-syntax.html#ngModel) chapters.

:marked
  Let’s update the template to use the  **`ngModel`** built-in directive for two-way binding.

  Replace the `<input>` with the following HTML

code-example(language="html").
  &lt;input [(ngModel)]="hero.name" placeholder="name">

:marked
  The browser refreshes. We see our hero again. We can edit the hero’s name and
  see the changes reflected immediately in the `<h2>`.

.l-main-section
:marked
  ## The Road We’ve Travelled
  Let’s take stock of what we’ve built.

  * Our Tour of Heroes uses the double curly braces of interpolation (a kind of one-way data binding)
  to display the application title and properties of a `Hero` object.
  * We wrote a multi-line template using ES2015’s template strings to make our template readable.
  * We can both display and change the hero’s name after adding a two-way data binding to the `<input>` element
  using the built-in `ngModel` directive.
  * The `ngModel` directive also propagates changes to every other binding of the `hero.name`.

  Run the <live-example></live-example> for this part.

  Here's the complete `app.component.ts` as it stands now:

+makeExample('toh-1/ts/src/app/app.component.ts', 'pt1', 'src/app/app.component.ts')

.l-main-section
:marked
  ## The Road Ahead
  Our Tour of Heroes only displays one hero and we really want to display a list of heroes.
  We also want to allow the user to select a hero and display their details.
  We’ll learn more about how to retrieve lists, bind them to the
  template, and allow a user to select a hero in the
  [next tutorial chapter](./toh-pt2.html).