验证Laravel中的对象数组

Question

我在Laravel 5.7表单请求类中有这些验证规则。前4行符合预期。最后一行没有。

'service_type' => 'required|alpha',
'trips.*.pu_location' => 'required_if:service_type,transfer,multi|string|nullable',
'trips.*.pu_address' => 'required_if:service_type,transfer,multi|string|nullable',
'trips.*.pu_location_code' => 'required|string|max:7',
'trips.*.pu_airline' => 'required_if:pu_location_code,AIRPORT'

我的控制器：

$reservation = $user->reservations()->create([
    ...
    'service' => $request->service_type,
    ...
]);

foreach ($request->trips as $trip) {
    $reservationTrips[] = $trip;
}

$reservation->trips()->createMany($reservationTrips);

有任何想法为什么会这样？