禁用角反应形式的字段 [英] Disable a field in angular reactive form

问题描述

在我的angular 6应用程序中，我正在制作一个具有以下形式的反应形式，

In my angular 6 application, i am making a reactive form which has,

HTML

<form [formGroup]="form">

    <h2>Click the add button below</h2>
    <button (click)="addCreds()">Add</button>
    <div formArrayName="credentials" >
      <div *ngFor="let creds of form.get('credentials').controls; let i = index" 
          [formGroupName]="i" style="display: flex">
          <select formControlName="action">
             <option *ngFor="let option of options" value="{{option.key}}">
               {{option.value}} 
             </option>
          </select>
          <input placeholder="Name" formControlName="name">
<div *ngIf="creds.value.action=='set' ||
      creds.value.action=='go'">
                   <input placeholder="Label" formControlName="label">
          </div>
      </div>
    </div>
    </form>

我在这里用过

<div *ngIf="creds.value.action=='set' || creds.value.action=='go'"> <input placeholder="Label" formControlName="label"> </div>

<div *ngIf="creds.value.action=='set' || creds.value.action=='go'"> <input placeholder="Label" formControlName="label"> </div>

如果条件为真，将显示字段label，否则将不显示.

which will display the field label if the condition is true or else it will not be displayed.

但是我只需要禁用该字段，而不应该将其完全删除.

But i need to only disable that field and should not remove it completely..

我尝试过的

<input [disabled]="creds.value.action != 'set' || creds.value.action != 'go' " placeholder="Label" formControlName="label">

<input [disabled]="creds.value.action != 'set' || creds.value.action != 'go' " placeholder="Label" formControlName="label">

但这是行不通的.

带有* ngIf 的Stackblitz https://stackblitz.com/edit/angular-form-array-example-25y1ix

Stackblitz with *ngIf https://stackblitz.com/edit/angular-form-array-example-25y1ix

已禁用的Stackblitz https://stackblitz .com/edit/angular-form-array-example-laftgu

如果所选的action(第一个下拉列表)值为wait，请帮助我如何禁用label字段.

Kindly help me how to disable the label field if the selected action (first dropdown) value is wait..

推荐答案

只需创建一个CSS类:

Just create a CSS class:

.disabled {
  pointer-events:none;
  background-color: #D3D3D3;
}

向组件添加方法

getValueByIndex(index) {
  const actionValue = ( < FormArray > this.form.get('credentials')).at(index).value.action;
  return actionValue !== 'set' && actionValue !== 'go';
}

在模板中使用此方法:

<input 
    [class.disabled]="getValueByIndex(i)" 
    placeholder="Label" 
    formControlName="label">

---

这是一个

Here's a Working Sample StackBlitz for your ref.

---

更新:

或者，您可以执行以下操作:

---

UPDATE:

Alternatively, you can do the following:

默认禁用label字段:

addCreds() {
  const creds = this.form.controls.credentials as FormArray;
  creds.push(this.fb.group({
    action: '',
    name: '',
    label: {
      value: '',
      disabled: true
    },
    state: 'na'
  }));
}

，然后侦听表单上的(ngModelChange)事件以更新标签字段的状态:

And then listen to the (ngModelChange) event on the form to update the state of the label field:

<select 
  formControlName="action"
  (ngModelChange)="($event === 'set' || $event === 'go') ? creds.controls.label.enable() : creds.controls.label.disable()">
  <option 
    *ngFor="let option of data" 
    [value]="option.key">
    {{option.value}} 
  </option>
</select>

---

这是一个

---

Here's a Working Sample StackBlitz for this approach.

感谢A.Winnen对使用以前方法的性能影响的评论.

Thanks to A.Winnen for his comments on the performance implications of using the previous approach.

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