如何处理Angular 2 RC5中的复选框组？

Question

我有一个表格，我希望用户编辑他想要收到的杂志订阅。代码如下：

零件：

export class OrderFormComponent {

    subscriptions = [
        {id: 'weekly', display: 'Weekly newsletter'},
        {id: 'monthly', display: 'Monthly newsletter'},
        {id: 'quarterly', display: 'Quarterly newsletter'},
    ];

    mySubs = [
        this.subscriptions[1]
    ]

    order = new FormGroup({
        subs: new FormArray(this.mySubs.map(sub => new FormControl(sub)), Validations.required) //Lost at this part
    });
}

模板：

<form [formGroup]="order">

<div formArrayName="subs">
    <label>Sign me up for newsletters</label>
    <p *ngFor="let s of subscriptions; let i=index">
        <input type="checkbox"  [value]="s.id" [formControlName]="i" /> {{ s.display }}
    </p>        
</div>

<div>
    <input type="checkbox" formControlName="agree" /> I agree to the terms and conditions.
</div>

{{ order.value | json }}

当我运行应用程序时，会显示三个复选框，但只检查了一个（错误的一个）。被检查的那个有标签，而其他没有。

我在这做错了什么？

Answer 1

好的，我终于明白了。

在我的组件中，我有：

// The order retrieved from the server
subscription = {
    schedules: [{id: 'weekly', display: 'Weekly update'}],
}

//The FormGroup element
this.subscriptionForm = new FormGroup({
        //Here I fill up a FormArray with some FormControls initialized to the
        //currently selected schedules
        schedules: new FormArray(this.subscription.schedules.map(schedule => new FormControl(schedule)), Validators.minLength(1))
    });

在视图中我有：

 <div>
    <label>Frequency</label>
    <p *ngFor="let schedule of viewData.schedules">
        <input type="checkbox" 
                [checked]="subscription.schedules.includes(schedule)" 
                (change)="changeSchedules(schedule)"> {{ schedule.display }}
    </p>
 </div>

这是课堂上的changeSchedules()方法：

changeSchedules(schedule: any) {
    var currentScheduleControls: FormArray = this.subscriptionForm.get('schedules') as FormArray;
    var index = currentScheduleControls.value.indexOf(schedule);
    if(index > -1) currentScheduleControls.removeAt(index) //If the user currently uses this schedule, remove it.
    else currentScheduleControls.push(new FormControl(schedule)); //Otherwise add this schedule.
}

奇迹般有效！表单按预期验证，在表单提交之前无需额外的方法来检索/合并订阅数组。

Answer 2

你在实例化FormControl时犯了一个错误。不是为所有选项创建FormControl的新实例，而是只创建一个（通过迭代你的mySub）。将您的代码更改为此类（未经测试）：

order = new FormGroup({
  // creating an array of form control with default values
  subs: new FormArray(this.subscriptions.map(sub => new FormControl(this.isSelectedSub(sub))), Validations.required)
});


//...
isSelectedSub(sub): boolean {
  return this.mySubs.indexOf(sub) >= 0;
}

在发送之前，您可能需要一个功能来将复选框合并到一系列选定的杂志订阅中。