angular-cn/toh-pt1.md at a1cfb5b2ae949b8a4f0af8433b55736e08cf5a4f

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@title 英雄编辑器

@intro 构建一个简单的英雄编辑器

@description

阅读指南（译者）

对于没有前端基础的同学来说，读本教程的时候可能会遇到一些陌生的名词。不要慌，你可以跳到词汇表查找对它的详细解释。

如果想对Angular的概念有一个宏观的了解，请先阅读架构概览。

Setup to develop locally

为本地开发搭建环境

Follow the setup instructions for creating a new project named angular-tour-of-heroes.

根据开发环境中的说明创建一个名为的新项目

The file structure should look like this:

该项目的文件结构应该是这样的：

angular-tour-of-heroes

<div class='file'>
  src
</div>

<div class='children'>

  <div class='file'>
    app
  </div>

  <div class='children'>

    <div class='file'>
      app.component.ts
    </div>

    <div class='file'>
      app.module.ts
    </div>

  </div>

  <div class='file'>
    main.ts
  </div>

  <div class='file'>
    index.html
  </div>

  <div class='file'>
    styles.css
  </div>

  <div class='file'>
    systemjs.config.js
  </div>

  <div class='file'>
    tsconfig.json
  </div>

</div>

<div class='file'>
  node_modules ...
</div>

<div class='file'>
  package.json
</div>

When you're done with this page, the app should look like this .

在我们完成本章时，得到的应用和这个一样。

{@a keep-transpiling}

Keep the app transpiling and running

保持应用不断转译和运行

Enter the following command in the terminal window:

在命令行窗口中输入以下命令：

npm start

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.

这个命令会在“监听”模式下运行TypeScript编译器，当代码变化时，它会自动重新编译。同时，该命令还会在浏览器中启动该应用，并且当代码变化时刷新浏览器。

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

在后续构建《英雄指南》过程中，应用能持续运行，而不用中断服务来编译或刷新浏览器。

Show the hero

显示此英雄

Add two properties to the AppComponent: a title property for the app name and a hero property for a hero named "Windstorm."

往AppComponent中添加两个属性：title属性用来表示应用的名字，而hero属性用来表示名叫“Windstorm”的英雄。

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

下面，更新@Component装饰器中指定的模板，为这些新属性建立数据绑定。

The browser refreshes and displays the title and hero name.

保存后，浏览器应自动刷新，显示标题和英雄。

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.

这里的双大括号是Angular中的插值表达式绑定语法。它们表示组件的title和hero属性的值会作为字符串插入到HTML标签中间。

Read more about interpolation in the Displaying Data page.

要了解插值表达式的更多知识，见显示数据。

Hero object

Hero 对象

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

显然，英雄还需要更多属性。让我们把hero从一个字符串字面量换成一个类。

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.

创建一个Hero类，它具有id和name属性。现在，把下列代码放在app.component.ts的顶部，仅次于 import 语句。

In the AppComponent class, refactor the component's hero property to be of type Hero, then initialize it with an id of 1 and the name Windstorm.

现在，有了一个Hero类，我们把组件hero属性的类型换成Hero。然后以1为 id、以 “Windstorm” 为名字，初始化它。

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.

我们把hero从一个字符串换成了对象，所以也得更新模板中的绑定表达式，来引用hero的name属性。

The browser refreshes and continues to display the hero's name.

浏览器自动刷新，并继续显示这位英雄的名字。

Adding HTML with multi-line template strings

使用多行模板字符串添加更多 HTML

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.

要显示英雄的所有属性，还要为英雄的id属性添加一个<div>，为英雄的name属性添加另一个<div>。为了保持模板的可读性，把每个<div>单独放一行。

The backticks around the component template let you put the <h1>, <h2>, and <div> elements on their own lines, thanks to the template literals feature in ES2015 and TypeScript. For more information, see Template literals.

反引号包裹的组件模板能让你把<h1>、<h2>和<div>元素各自放在一行上。感谢ES2015和TypeScript的模板字面量特性。要了解更多，请参见模板字面量（Template literals）页。

Edit the hero name

编辑英雄名字

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.

用户应该能在一个<input>输入框中编辑英雄的名字。当用户输入时，这个输入框应该能同时显示和修改英雄的name属性。

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

也就是说，我们要在表单元素<input>和组件的hero.name属性之间建立双向绑定。

Two-way binding

双向绑定

Refactor the hero name in the template so it looks like this:

把模板中的英雄名字重构成这样：

[(ngModel)] is the Angular syntax to bind the hero.name property to the textbox. Data flows in both directions: from the property to the textbox, and from the textbox back to the property.

[(ngModel)]是一个Angular语法，用与把hero.name绑定到输入框中。它的数据流是双向的：从属性到输入框，并且从输入框回到属性。

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."

不幸的是，做了这项改动之后，我们的程序崩溃了。打开浏览器的控制台，我们会看到Angular抱怨说：“ngModel ... isn't a known property of input.”（ngModel不是input元素的已知属性）

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.

虽然NgModel是一个有效的Angular指令，但它默认情况下却是不可用的。它属于一个可选模块FormsModule。我们必须选择使用那个模块。

Import the FormsModule

导入 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.

打开app.module.ts文件，并且从@angular/forms库中导入符号FormsModule。然后把FormsModule添加到@NgModule元数据的imports数组中，它是当前应用正在使用的外部模块列表。

The updated AppModule looks like this:

修改后的AppModule是这样的：

Read more about FormsModule and ngModel in the Two-way data binding with ngModel section of the Forms guide and the Two-way binding with NgModel section of the Template Syntax guide.

要学习关于FormsModule和ngModel的更多知识，参见表单和模板语法。

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.

浏览器刷新。又见到我们的英雄了。我们可以编辑英雄的名字，也能看到这个改动立刻体现在<h2>中。

Summary

我们已经走过的路

Take stock of what you've built.

我们来盘点一下已经构建完成的部分。

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.

我们的《英雄指南》使用双大括号插值表达式(单向数据绑定的一种形式)来显示应用的标题和Hero对象的属性。
You wrote a multi-line template using ES2015's template literals to make the template readable.

我们使用 ES2015 的模板字符串写了一个多行模板，使我们的模板更具可读性。
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.

为了同时显示和修改英雄的名字，我们还使用了内置的ngModel指令，往<input>元素上添加了双向数据绑定。
The ngModel directive propagates changes to every other binding of the hero.name.

ngModel指令将这些修改传播到每一个对hero.name的其它绑定。

Your app should look like this .

运行这部分的。

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

完整的app.component.ts是这样的：

Next step

下一步

In the next tutorial page, 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.

在教程的下一章，我们将在这个《英雄指南》中显示一个英雄列表。我们将允许允许用户选择英雄，并显示他们的详情。我们还将学会如何获取列表以及将它们绑定到模板中。

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