angular - 响应式(Reactive)表单数组 - 推送新元素时避免验证错误

Question

我有一个由单个表单数组组成的表单组:

ngOnInit() {
    this.deviceDetailsFormGroup = this._formBuilder.group({
        deviceDetails: this._formBuilder.array([
            this.buildDeviceDetailsForm()
        ])
    });
}

Form Array 中的每个控件都需要验证器:

buildDeviceDetailsForm(): FormGroup {
    return this._formBuilder.group({
        ipAddressCtrl: [
            "",
            [Validators.pattern(ipaddressPattern), Validators.required]
        ],
        hostnameCtrl: [
            "",
            [
                Validators.required,
                Validators.maxLength(30),
                Validators.minLength(5)
            ]
        ]
    });
}

下面是我对 Form Array 的 push 和 remove 函数:

addNewDevice() {
    this.deviceItems = this.deviceDetailsFormGroup.get(
        "deviceDetails"
    ) as FormArray;

    if (this.deviceItems.length > MAX_DEVICES) {
        this.toastNotif.errorToastNotif(
            `A maximum of ${MAX_DEVICES} devices can be selected for a single job scan`,
            "Too many devices selected"
        );
        return;
    }

    if (this.deviceDetailsFormGroup.invalid) {
        return;
    }

    let mapIP = new Map<string, number>();

    // Warn about duplicate IP's in form
    this.deviceItems.controls.forEach(ctrl => {
        if (mapIP[ctrl.value.ipAddressCtrl] === 0) {
            this.toastNotif.warningToastNotif(
                "You have entered duplicate IP's in the form fields",
                "Duplicate" + " IP's"
            );
        }

        mapIP[ctrl.value.ipAddressCtrl] = 0;
    });

    this.deviceItems.push(this.buildDeviceDetailsForm());
}

removeDevice(i: number) {
    this.deviceItems.removeAt(this.deviceItems.length - 1);
}

当我将新元素推送到 Form Array 时，它们被标记为无效，尽管它们未受影响且原始。我知道这是由创建新的 FormGroup 时设置的验证器和空默认值引起的。
是否可以避免这种行为，以便 FormArray 元素仅在被触摸时才被标记为错误？
提前致谢。

Answer 1

Luca，FormArray 中的formControl 会一直无效，所以FormArray 无效，表单无效。您需要检查是否触摸了控件。 this stackblitz 中的一个简单示例。你看你加的话，控件无效，但是没碰过

.html 是一种典型的形式

<button (click)="add()">Add</button>
<form [formGroup]="myForm">
<div formArrayName="myFormArray">
  <div *ngFor="let group of myFormArray.controls;let i=index" [formGroupName]="i">
       <input formControlName="name">
       <!--show only after touched and invalid-->
       <div *ngIf="group.get('name').touched && group.get('name').invalid">
         invalid and touched
       </div>
       <!--show always when add a new formGroup to array-->
       <div *ngIf="group.get('name').invalid">
         invalid 
       </div>
  </div>
  </div>
  </form>

.ts 是“经典”

myForm=new FormGroup({
     myFormArray:new FormArray([])
  })

  get myFormArray()
  {
    return this.myForm.get('myFormArray') as FormArray
  }
  createGroup()
  {
    return new FormGroup({
      name:new FormControl('',Validators.required)
    })
  }
  add()
  {
    this.myFormArray.push(this.createGroup())
  }