why does this count in nova metric not work?

Question

If i count my User::class model, the metrics work, but when i change it to another model the metric shows

" 0 No Data "

<?php


namespace App\Nova\Metrics;

use App\Kunde;
use Illuminate\Http\Request;
use Laravel\Nova\Metrics\Value;

class TotalKunden extends Value
{

/**
  * Calculate the value of the metric.
  *
 *
public function calculate()
{
return $this->result(Kunde::count());
}
 *
  *@param \Illuminate\Http\Request $request
  *@return mixed
  */

  public function calculate(Request $request)
  {
      return $this->count($request, Kunde::class);
  }




/**
* Get the ranges available for the metric.
**/

public function ranges()
{
    return [
        30 => '30 Tage',
        60 => '60 Tage',
        365 => '1 Jahr',
        'MTD' => 'Seit Monatsbeginn',
        'QTD' => 'Seit Quartalbeginn',
        'YTD' => 'Seit Jahresanfang',

    ];
}

}   

my model is referenced in the resource

with:

    public static $model = 'App\Kunde';

and there is no error in the logs

only this works,

 public function calculate()
{
return $this->result(Kunde::count());
}

but then the ranges are not working.

Answer 1

maybe someone has the same problem.. so the answer is:

metrics query is looking for the created_at column in the DB, so it must have an date

the metrics query is like this..

SELECT count(`id`) as aggregate FROM `Objects` WHERE `created_at` between '2018-11-05         12:51:22' and '2018-12-05 12:51:22' and `Objects`.`deleted_at` IS NULL

:)