Angular FormGroup 中的 2/4 FormControl 无法在带有标签的表单上显示

Question

我不明白该怎么做

1. console.log 特定值
2. 显示在 HTML 页面的标签中
3. 在输入文本中显示

这是我的组件 Typescript，带有新的 FormGroup，然后是新的 FormControls

    this.trackerForm = new FormGroup({
        session: new FormControl('', Validators.required),
        date: new FormControl(new Date(), [
            Validators.required
        ]),
        contactType: new FormControl('', [
            Validators.required
        ]),
        customerType: new FormControl('', Validators.required),
        firstName: new FormControl('', [Validators.required, Validators.minLength(80)]),
        lastName: new FormControl('', [Validators.required, Validators.minLength(80)]),
        phone: new FormControl('', [Validators.required, Validators.maxLength(10), Validators.minLength(10)]),
        extension: new FormControl('', [Validators.maxLength(7)])

    });

    // this outputs the entire json
    console.log(JSON.stringify(this.trackerForm.value));
    //How do I ONLY console.log  one of the values?   date?

HTML 页 -

<form [formGroup]="trackerForm" (ngSubmit)="onSubmit(trackerForm.value)" novalidate>

 <div>
      <label class="form-control"><span>{{trackerForm.date.value}}  </span></label>
    </div>

Answer 1

您需要通过 trackerForm.controls 对象访问 formGroup 控件。

"date" 控件值 trackerForm.controls['date'].value 的示例。

Answer 2

<form [formGroup]="trackerForm" (ngSubmit)="onSubmit(trackerForm.value)" novalidate>

 <div>
      <label class="form-control"><span>{{trackerForm.get('date').value}}  </span></label>
    </div>

或

<label class="form-control"><span>{{trackerForm.controls['date'].value}}  </span></label>

但第一个肯定更好，因为 'AOT' 不编译第二个。

但我会创建一个组件 getter 以使其更好：

 get dateControl(){
     return this.trackerForm.get('date');
 }

然后：

    <form [formGroup]="trackerForm" (ngSubmit)="onSubmit(trackerForm.value)" novalidate>

 <div>
      <label class="form-control"><span>{{dateControl.value}}  </span></label>
    </div>