Laravel Input :: GET不适用于Carbon

Question

This is quite the interesting situation:

As per laravel's documentation, the 2nd parameter of Input::get() returns a default if none is present.

Unfortunately this line throws an error "data missing" when data-from is missing, despite specifying a default:

Carbon::createFromFormat('Y/m/d',Input::get('date-from','2015/01/01'))

Full Code:

try
{
    $dateFrom = Carbon::createFromFormat('Y/m/d',Input::get('date-from','2015/01/01'));
}
catch(InvalidArgumentException $e)
{
    return Response::make($e->getMessage(),500);
}

However, if i do:

Input::has('date-from') ? Carbon::createFromFormat('Y/m/d',Input::get('date-from')) : new Carbon('2015/01/01')

It works perfectly.

The question is simply: why?