Laravel group by如果没有行，则返回零

I am listing last 16 days num of views. I want to write 0; if there is not row at date:

$digital_case_daily_views = DB::table('digital_case_views')
->select(DB::raw('count(*) as numOfDigitalCaseViews'))->groupBy('created_at')
->orderBy('created_at', 'desc')->limit(16)->get();

laravel 5.6

it returns like:

    "digital_case_daily_views": [
        {
            "numOfDigitalCaseViews": 162
        },
        {
            "numOfDigitalCaseViews": 458
        },
        {
            "numOfDigitalCaseViews": 287
        },
        {
            "numOfDigitalCaseViews": 1
        },
        {
            "numOfDigitalCaseViews": 1
        },
        {
            "numOfDigitalCaseViews": 1
        }

you can't get more rows from the database than available, if you want to have 0 for the remaining days, you have to add them to the array, I've written a function for you that might help you with this:

class Foo {
    static public function addRemainingDays(array $arr, int $amount) {
        if(count($arr) === $amount) {
            return $arr;
        }

        for($i = 0; i > $amount - count($arr); i++) {
            array_push($arr, (object)["numOfDigitalCaseViews" => 0]);
        }

        return $arr
    }
}