Angular Reactive Form的深层副本？

Question

我正在尝试构建一个能够生成给定FormGroup副本的函数。我开始时：

function copyForm(form: FormGroup): FormGroup {
  const copy = new FormGroup({});
  for (let key of Object.keys(form.value)) {
    const control = form.controls[key];

    /* Copy the data from the control into a new control */
    const copyControl = new FormControl({[key]: control.value});

    copy.addControl(key, copyControl);
 }

但是，如果有FormArray或FormGroup，这不起作用。如果它是递归的，这个可能会起作用，但我无法很好地处理它。

我也试图解决它

function copyForm(form: FormGroup): FormGroup {
  const copy = new FormGroup({});
  for (let key of Object.keys(form.value)) {
    const control = form.controls[key];
    const copyControl = new FormControl({...control.value});
    copy.addControl(key, copyControl);
  }
  return copy;

}

但这不适用于双嵌套FormGroups，任何FormArrays或常规FormControls ......

我也尝试过：

function copyForm(form: FormGroup): FormGroup {
  const copy = new FormGroup(Object.assign({}, form.value));
  return copy;
}

但这给了我错误：

ERROR TypeError: control.setParent is not a function

我很难过。

Answer 1

这是我提出的深层复制功能，它还保留了每个AbstractControl的相关验证器/异步验证器功能和禁用状态。

/**
 * Deep clones the given AbstractControl, preserving values, validators, async validators, and disabled status.
 * @param control AbstractControl
 * @returns AbstractControl
 */
export function cloneAbstractControl<T extends AbstractControl>(control: T): T {
  let newControl: T;

  if (control instanceof FormGroup) {
    const formGroup = new FormGroup({}, control.validator, control.asyncValidator);
    const controls = control.controls;

    Object.keys(controls).forEach(key => {
      formGroup.addControl(key, cloneAbstractControl(controls[key]));
    })

    newControl = formGroup as any;
  }
  else if (control instanceof FormArray) {
    const formArray = new FormArray([], control.validator, control.asyncValidator);

    control.controls.forEach(formControl => formArray.push(cloneAbstractControl(formControl)))

    newControl = formArray as any;
  }
  else if (control instanceof FormControl) {
    newControl = new FormControl(control.value, control.validator, control.asyncValidator) as any;
  }
  else {
    throw new Error('Error: unexpected control value');
  }

  if (control.disabled) newControl.disable({emitEvent: false});

  return newControl;
}

Answer 2

我就是这样做的：

copyFormControl(control: AbstractControl) {
    if (control instanceof FormControl) {
        return new FormControl(control.value);
    } else if (control instanceof FormGroup) {
        const copy = new FormGroup({});
        Object.keys(control.getRawValue()).forEach(key => {
            copy.addControl(key, copyFormControl(control.controls[key]));
        });
        return copy;
    } else if (control instanceof FormArray) {
        const copy = new FormArray([]);
        control.controls.forEach(control => {
            copy.push(copyFormControl(control));
        })
        return copy;
    }
}

我使用的是getRawValue()而不是value，因为value不会包含禁用的控件。

Answer 3

我个人使用lodash cloneDeep（）函数在这里找到：

https://lodash.com/docs/#cloneDeep

我用这种方式：

const newFormGroup: any = _.cloneDeep(myFormGroup);

Answer 4

对于仅包含FormControls的简单FormGroup（即不包含FormGroups或FormArrays）：

cloneForm(formGroup: FormGroup){
    let x = new FormGroup({});
    x.patchValue(formGroup.value);
    return x;
}