Laravelでeloquentを使用する方法

if($request->filter_by == 'amount')
{
    $query->where('amount', '>', request('amount', 0));
}

if($request->filter_by == 'created_at')
{
    $query->orderBy('created_at', request('order', 'desc'));
}

$query = Order::query();

$query->when(request('filter_by') == 'amount', function($q){
    return $q->where('amount','>', request('amount',0));
});
$query->when(request('filter_by') == 'created_at', function($q){
    return $q->orderBy('created_at', request('order','desc'));
});

$query = Order::query();
$query->when(request('filter_by') == 'amount', function($q){
    return $q->where('amount','>', request('amount',0));
}, function($q){
    return $q->orderBy('created_at', request('order','desc'));
})->get();