Laravel雄辩的嵌套关系组

Question

我有Spot，DealItem和Daypart三种模型，每种模型都有自己的关系

class Spot extends Model
{
   protected $table = 'avt_spot';
   public $timestamps = false;

   public function dealItem()
   {
       return $this->belongsTo('App\SkyDealitem', 'deal_core_service_id', 'core_service_id');
   }
}

class SkyDealItem extends Model
{
    protected $table = 'sky_deal_item';
    public $timestamps = false;

    public function daypart()
    {
        return $this->belongsTo('App\Daypart','daypart_code_id','id');
    }
}

class Daypart extends Model
{
    protected $table = 'avt_US_daypart';
    public $timestamps = false;

    public function deals()
    {
        return $this->hasMany('App\DealItem','daypart_code_id','id');
    }
}

每个地点都会有一个名为pre_eval_tvr的列，既属于DealItem，也属于广告系列

每个DealItem都属于时段。

仅供参考-一个广告系列将有多个位置

现在我正在查询的查询是使用关系的按天明智pre_eval_tvr。

仅使用普通联接查询就可以获取，但是使用嵌套关系无法获取。

仅供参考-加入查询

select sum(avt_spot.pre_eval_tvr) as pre_eval_tvr, avt_US_daypart.*
from avt_spot
inner join sky_deal_item on avt_spot.deal_core_service_id = sky_deal_item.core_service_id
inner join avt_US_daypart on avt_US_daypart.id = sky_deal_item.daypart_code_id
where avt_spot.allocated_to_campaign = 4442
group by avt_US_daypart.id;