selectorfactory.ts

// example for single field
const validators = {
  validatorKey: validatorFunction,
};

function validatorFunction(value): boolean {
  return true;
}

const isValid = (value, validatorKeys: Array<string>): boolean => {
  return validatorKeys.reduce((valIsValid, key) => validators[key](value), true);
}

const createFormFieldSelector = <T>(fieldPath: string[]) =>
  createSelector(
    formStateSelector,
    (form: IForm) => path<T>(fieldPath, form)
  );

const createValidatorSelector = (fieldPath, validatorKeys) => {
  return createSelector(
    createFormFieldSelector(fieldPath),
    (fieldValue) => isValid(fieldPath, validatorKeys),
  );
}




// in your component
@select(createValidatorSelector(fieldPath, validatorKeys))
isFieldValid$: Observable<boolean>;; //Observable boolean