wanyue_app/app/model/Device.php

<?php

namespace app\model;

use DateTimeInterface;
use support\Model;

class Device extends Model
{
    protected $table = 'device';

    protected $primaryKey = 'device_id';

    protected $keyType = 'string';

    protected $dateFormat = 'U';

    const CREATED_AT = 'device_addtimes';

    const UPDATED_AT = null;

    public function serializeDate(DateTimeInterface $date)
    {
        return $date->format('Y-m-d H:i:s');
    }

    public function ledger()
    {
        return $this->hasOne(DeviceLedger::class, 'device_ledger_id', 'join_device_ledger_id')
            ->select('device_ledger_id', 'device_ledger_name');
    }
}