198 lines
10 KiB
Plaintext
198 lines
10 KiB
Plaintext
include ../_util-fns
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:marked
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We can't always justify the cost and time to build handcrafted forms,
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especially if we'll need a great number of them, they're similar to each other, and they change frequently
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to meet rapidly changing business and regulatory requirements.
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我们不可能一直觉得手动编写表单和需要的工作量和时间成正比，特别是当我们需要编写大量的表单，他们非常类似，而且他们需要随着商务和政策需求的迅速变化而变化。
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It may be more economical to create the forms dynamically, based on metadata that describe the business object model.
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基于商务对象模型里面的元数据，动态建立表单可能更加划算。
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In this cookbook we show how to use `ngFormModel` to dynamically render a simple form with different control types and validation.
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It's a primitive start.
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It might evolve to support a much richer variety of questions, more graceful rendering, and superior user experience.
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All such greatness has humble beginnings.
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在本文中，我们会展示怎么利用`ngFormModel`动态渲染一个简单的表单， 包含不同类型控制器和验证规则。
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这是一个原始的开始，任何伟大都是从谦卑开始的。我们可以在这个基础上添加种类丰富的问卷问题，更加优美的渲染和更优越的用户体验。
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In our example we use a dynamic form to build an online application experience for heroes seeking employment.
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The agency is constantly tinkering with the application process.
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We can create the forms on the fly *without changing our application code*.
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在这个例子中，我们使用动态表单，为正在找工作的英雄们创建一个在线申请体验。中介在不断的修改申请流程。我们可以在*不修改程序*的情况下，动态即时的建立一个表格
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<a id="toc"></a>
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:marked
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## Table of contents
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## 目录
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[问卷问题模型Question Model](#object-model)
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[表单组件Form Component](#form-component)
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[问卷元数据Questionnaire Metadata](#questionnaire-metadata)
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[动态模板Dynamic Template](#dynamic-template)
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:marked
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**See the [live example](/resources/live-examples/cb-dynamic-form/ts/plnkr.html)**.
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**请看[在线例子](/resources/live-examples/cb-dynamic-form/ts/plnkr.html)**.
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.l-main-section
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<a id="object-model"></a>
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:marked
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## Question Model
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## 问卷问题模型
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The first step is to define an object model that can describe all scenarios needed by the form functionality.
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The hero application process involves a form with a lot of questions.
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The "question" is the most fundamental object in the model.
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第一步是定义一个对象模型，用来描述所有表单功能需要的场景。英雄申请流程涉及到一个有很多问卷问题的表单。问卷问题是最基础的对象模型。
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We have created `QuestionBase` as the most fundamental question class.
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下面是我们建立的非常基础的问卷问题类，名叫`QuestionBase`。
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+makeExample('cb-dynamic-form/ts/app/question-base.ts','','app/question-base.ts')
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:marked
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From this base we derived two new classes in `TextboxQuestion` and `DropdownQuestion` that represent Textbox and Dropdown questions.
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The idea is that the form will be bound to specific question types and render the appropriate controls dynamically.
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在这个基础上，我们衍生了两个新类`TextboxQuestion` 和 `DropdownQuestion`，分别代表文本框和下拉框。这么做的初衷是，表单能动态的绑定特定的问卷问题类型，并动态渲染合适的控制器。
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`TextboxQuestion` supports multiple html5 types like text, email, url etc via the `type` property.
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`TextboxQuestion`通过`type`属性，支持多种HTML5元素类型，比如文本、邮件、网址等。
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+makeExample('cb-dynamic-form/ts/app/question-textbox.ts',null,'app/question-textbox.ts')(format='.')
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:marked
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`DropdownQuestion` presents a list of choices in a select box.
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`DropdownQuestion`代表一个拥有一个列表可选项目的选择框。
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+makeExample('cb-dynamic-form/ts/app/question-dropdown.ts',null,'app/question-dropdown.ts')(format='.')
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:marked
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Next we have defined `QuestionControlService`, a simple service for transforming our questions to an ngForm control group.
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In a nutshell, the control group consumes the metadata from the question model and allows us to specify default values and validation rules.
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下一步，我们定义了`QuestionControlService`，一个可以把我们的问卷问题转换为ngForm控制组的服务。简而言之，这个ngForm控制组使用问卷模型的元数据，允许我们制定默认值和验证规则。
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+makeExample('cb-dynamic-form/ts/app/question-control.service.ts',null,'app/question-control.service.ts')(format='.')
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<a id="form-component"></a>
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:marked
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## Question form components
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## 问卷表单组件
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Now that we have defined the complete model we are ready to create components to represent the dynamic form.
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现在我们已经有一个已定义的完整模型，我们可以创建一个动态表单的组件。
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:marked
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`DynamicForm` is the entry point and the main container for the form.
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`DynamicForm`是我们表单的主要载体和切入口。
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+makeTabs(
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`cb-dynamic-form/ts/app/dynamic-form.component.html,
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cb-dynamic-form/ts/app/dynamic-form.component.ts`,
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null,
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`dynamic-form.component.html,
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dynamic-form.component.ts`
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)
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:marked
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It presents a list of questions, each question bound to a `<df-question>` component element.
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The `<df-question>` tag matches the `DynamicFormQuestionComponent`,
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the component responsible for rendering the details of each _individual_ question based on values in the data-bound question object.
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它显示一个问卷问题的列表，每个问题都在`<df-question>`组件元素之内。`<df-question>`对应于`DynamicFormQuestionComponent`，该组件的作用是根据问卷问题对象的值来渲染每个问卷问题的细节。
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+makeTabs(
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`cb-dynamic-form/ts/app/dynamic-form-question.component.html,
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cb-dynamic-form/ts/app/dynamic-form-question.component.ts`,
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null,
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`dynamic-form-question.component.html,
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dynamic-form-question.component.ts`
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)
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:marked
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Notice this component can present any type of question in our model.
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We only have two types of questions at this point but we can imagine many more.
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The `ngSwitch` determines which type of question to display.
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请注意，这个组件能代表模型里的任何问卷问题类型。目前，我们只有两种类型的问卷问题，但是我们可以添加更多类型。`ngSwitch`确定显示哪一个类型的问卷问题。
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In both components we're relying on Angular's **ngFormModel** to connect the template HTML to the
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underlying control objects, populated from the question model with display and validation rules.
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在两个组件中，我们依赖Angular的**ngFormModel**来把模板HTML链接到底层控制对象，该对象已经从问卷问题模型里获取了显示和验证规则，
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<a id="questionnaire-metadata"></a>
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:marked
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## Questionnaire data
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## 问卷数据
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:marked
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`DynamicForm` expects the list of questions in the form of an array bound to `@Input() questions`.
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`DynamicForm`预期得到一个问题列表，该列表是一个关联到`@Input() questions`数组。
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The set of questions we have defined for the job application is returned from the `QuestionService`.
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In a real app we'd retrieve these questions from storage.
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`QuestionService`返回我们在定义工作申请表的时候设定的这套问题。在一个真实的应用程序中，我们会从存储库里面提取。
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The key point is that we control the hero job application questions entirely through the objects returned from `QuestionService`.
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Questionnaire maintenance is a simple matter of adding, updating, and removing objects from the `questions` array.
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最关键的点是，我们全部通过从`QuestionService`返回的对象，来控制英雄工作申请问卷。要维护问卷，我们要做的是非常简单的添加、更新和删除`问题`数组中的对象。
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+makeExample('cb-dynamic-form/ts/app/question.service.ts','','app/question.service.ts')
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:marked
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Finally, we display an instance of the form in the `AppComponent` shell.
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最后，我们在`AppComponent`里面显示表单。
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+makeExample('cb-dynamic-form/ts/app/app.component.ts','','app.component.ts')
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<a id="dynamic-template"></a>
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:marked
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## Dynamic Template
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## 动态模板
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Although in this example we're modelling a job application for heroes, there are no references to any specific hero question
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outside the objects returned by `QuestionService`.
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虽然在这个例子中，我们是在为英雄工作申请表建模，但是除了`QuestionService`返回的对象外，没有其他任何地方有指定英雄问卷相关的内容。
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This is very important since it allows us to repurpose the components for any type of survey
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as long as it's compatible with our *question* object model.
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The key is the dynamic data binding of metadata used to render the form
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without making any hardcoded assumptions about specific questions.
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In addition to control metadata, we are also adding validation dynamically.
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这点非常重要的，因为只要与我们的*问卷*对象模型兼容，它允许我们为任何类型的调查重复使用这些组件。关键是运用动态数据绑定的元数据来渲染表单，不对问卷问题有任何硬性的假设。除了控制起元数据外，我们还可以动态添加验证规则。
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The *Save* button is disabled until the form is in a valid state.
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When the form is valid, we can click *Save* and the app renders the current form values as JSON.
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This proves that any user input is bound back to the data model.
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Saving and retrieving the data is an exercise for another time.
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在表单的验证通过之前，*保存*按钮是禁用的。当表单验证通过后，我们可以点击*保存*，程序会把当前的值渲染成为Json。它证明了任何用户输入都被传到了数据模型。如何储存和提取数据是另一个问题。
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:marked
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The final form looks like this:
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完整表单看起来是这样：
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figure.image-display
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img(src="/resources/images/cookbooks/dynamic-form/dynamic-form.png" alt="Dynamic-Form")
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:marked
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[Back to top](#top)
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[回到顶部](#top)
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