Angular 2動態表單如何根據另一個字段的值顯示/隱藏字段

Question

環境：Angular 2 RC 4，打字稿。

我有一個動態角度形式的實現。 我總共有4個字段-DOB，電子郵件，問題和答案

問題：

dob: new TextboxQuestion({
      key: 'dob',
      label: 'Date of Birth',
      value: '',
    }),


    email: new TextboxQuestion({
      key: 'email',
      label: 'Email Address',
      value: '',
      type: 'email',
    }),

    securityQuestion: new TextboxQuestion({
      key: 'challengeQuestion',
      label: 'Security Question',
      value: '',
      disabled: true
    }),
    securityAnswer: new TextboxQuestion({
      key: 'challengeAnswer',
      label: 'Write your answer',
      value: '',
    })

主要/父組件的html代碼段

<dynamic-form (responsesEvt)="onFormSubmitResponseReceived($event);" [sections]="sections" class="col-md-8"></dynamic-form> 

動態形式組件

<form (ngSubmit)="onSubmit()" [formGroup]="form"> 
            <div *ngFor="let question of questions" class="form-row" >
                <df-question [question]="question" [form]="form" *ngIf="!section.hidden"></df-question>
            </div>

        <div class="row">
            <div class="col-md-5"></div>
            <div class="col-md-7 btn-row">
                <button type="submit" class="btn btn-primary pull-right" [disabled]="!form.valid">I agree with the Terms & Conditions</button>
                <!--<button type="submit" class="btn btn-primary pull-right" [disabled]="!form.valid || subbmittedalready">I agree with the Terms & Conditions</button>-->
                <button type="button" class="btn btn-default pull-right">Cancel</button>
            </div>
        </div>
    </form>

df-問題組件

<div [formGroup]="form">
  <div class="col-md-5"><label class="pull-right" [attr.for]="question.key"><span class="errorMessage">*&nbsp;</span>{{question.label}}</label></div>
  <div class="col-md-7" [ngSwitch]="question.controlType">
    <input *ngSwitchCase="'textbox'" [formControlName]="question.key" [id]="question.key" [type]="question.type" class="form-control"
      [placeholder]="question.placeHolder"
       />
  </div>
  <div class="col-md-5"></div>
</div>  

這是我的工作流程

Step 1 Initially at form load, only dob and email show up.
Step 2 User types in the dob and email. DOB and email are sent to the backend and if the info is correct, a "question" is returned.
Step 3 Now the question and answer fields appear (assuming that above step was successful). The question field is populated with the value returned from the server through the previous request
Step 4 User submits the form with dob, email, question and answer

關於如何使用動態表單實現這一點的任何想法？

我想我可以在dob之后以某種方式引發事件，填寫電子郵件，致電后端並提出問題。 使用一個變量來隱藏/顯示問題並根據上述響應的成功/失敗進行回答？

如果這是一個好方法，我怎么能感覺到用戶已經填寫了前兩個字段並進行了后端調用。 收到服務器回復后，如何更新問題字段（特別是使用動態表單）？

如果沒有，有沒有更簡單的方法可以做到這一點？

Answer 1

我知道這是一個延遲的答案，但是我認為Scotch.io的這篇帖子基本上涵蓋了您需要做的基本工作。

您創建一個表單組並根據字段的值交換出驗證，然后在視圖中隱藏使用ngIfs禁用的字段。