angular - Angular Reactive Form 的深拷贝？

Question

我正在尝试构建一个函数来生成给定 FormGroup 的副本。我开始于:

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);
 }

但如果有 FormArray 或 FormGroup，那将不起作用。 如果它是递归的，它可能会工作，但我无法很好地处理它。

我也尝试用

来解决它

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的 FormGroups、任何 FormArrays 或常规 FormControls...

我也试过:

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

这是我想出的深度复制功能，它还保留了每个 AbstractControl 的关联验证器/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;
}