include ../_util-fns

:marked
  ## Setup to develop locally
  Follow the [setup](../guide/setup.html) instructions for creating a new project
  named <ngio-ex path="angular-tour-of-heroes"></ngio-ex>.

  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 you're done with this page, the app should look like this <live-example></live-example>.

a#keep-transpiling
:marked
  ## Keep the app transpiling and running
  Enter the following command in the terminal window:

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

:marked
  This command runs the TypeScript compiler in "watch mode", recompiling automatically when the code changes.
  The command simultaneously launches the app in a browser and refreshes the browser when the code changes.

  You can keep building the Tour of Heroes without pausing to recompile or refresh the browser.

.l-main-section
  :marked
    ## Show the hero
    Add two properties to the `AppComponent`: a `title` property for the app name and a `hero` property
    for a hero named "Windstorm."

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

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

  +makeExample('toh-1/ts/app/app.component.1.ts', 'show-hero',  'app.component.ts (@Component)')(format='.')

  :marked
    The browser refreshes and displays the title and hero name.

    The double curly braces are Angular's *interpolation binding* syntax.
    These interpolation bindings present the component's `title` and `hero` property values,
    as strings, inside the HTML header tags.

.l-sub-section
  :marked
    Read more about interpolation in the [Displaying Data](../guide/displaying-data.html) page.

:marked
  ### Hero object

  The hero needs more properties.
  Convert the `hero` from a literal string to a class.

  Create a `Hero` class with `id` and `name` properties.
  Add these properties 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
  In the `Hero` class, refactor the 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 you changed the hero from a string to an object,
  update the binding in the template to refer to the hero's `name` property.

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

  ### Adding HTML with multi-line template strings

  To show all of the hero's properties,
  add a `<div>` for the hero's `id` property and another `<div>` for the hero's `name`.
  To keep the template readable, place each `<div>` on its own line.

  The backticks around the component template let you put the `<h1>`, `<h2>`, and `<div>` elements on their own lines,
  thanks to the <i>template literals</i> feature in ES2015 and TypeScript. For more information, see
  <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals" target="_blank" title="template literal">Template literals</a>.


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

.l-main-section
:marked
  ## Edit the hero name

  Users should be able to edit the hero name in an `<input>` textbox.
  The textbox should both _display_ the hero's `name` property
  and _update_ that property as the user types.

  You need a two-way binding between the `<input>` form element and the `hero.name` property.

  ### Two-way binding

  Refactor the hero name in the template so it looks like this:
+makeExample('toh-1/ts/app/app.component.1.ts', 'name-input')(format='.')

:marked
  `[(ngModel)]` is the Angular syntax to bind the `hero.name` property
  to the textbox.
  Data flow _in both directions_: from the property to the textbox;
  and from the textbox back to the property.

  Unfortunately, immediately after this change, the application breaks.
  If you looked in the browser console, you'd see Angular complaining that
  "`ngModel` ... isn't a known property of `input`."

  Although `NgModel` is a valid Angular directive, it isn't available by default.
  It belongs to the optional `FormsModule`.
  You must opt-in to using that module.

  ### Import the _FormsModule_

  Open the `app.module.ts` file and import the `FormsModule` symbol from the `@angular/forms` library.
  Then add the `FormsModule` to the `@NgModule` metadata's `imports` array, which contains the list
  of external modules that the app uses.

  The updated `AppModule` looks like this:
+makeExample('toh-1/ts/src/app/app.module.ts', '', 'app.module.ts (FormsModule import)')

.l-sub-section
  :marked
    Read more about `FormsModule` and `ngModel` in the
    [Two-way data binding with ngModel](../guide/forms.html#ngModel) section of the
    [Forms](../guide/forms.html) guide and the
    [Two-way binding with NgModel](../guide/template-syntax.html#ngModel) section of the
    [Template Syntax](../guide/template-syntax.html) guide.

:marked
  When the browser refreshes, the app should work again.
  You can edit the hero's name and see the changes reflected immediately in the `<h2>` above the textbox.

.l-main-section
:marked
  ## The road you've travelled
  Take stock of what you've built.

  * The Tour of Heroes app uses the double curly braces of interpolation (a type of one-way data binding)
  to display the app title and properties of a `Hero` object.
  * You wrote a multi-line template using ES2015's template literals to make the template readable.
  * You added a two-way data binding to the `<input>` element
  using the built-in `ngModel` directive. This binding both displays the hero's name and allows users to change it.
  * The `ngModel` directive propagates changes to every other binding of the `hero.name`.

  Your app should look like this <live-example></live-example>.

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

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


.l-main-section
:marked
  ## The road ahead
  In the [next tutorial page](./toh-pt2.html), you'll build on the Tour of Heroes app to display a list of heroes.
  You'll also allow the user to select heroes and display their details.
  You'll learn more about how to retrieve lists and bind them to the template.
