yxx_belongs_to_many.md

laravel Orm 多对多 id 错乱

Model

    WasherTeam
	id
	name

    VehicleLocationArea
	id
	name
	lat_lng

    WasherTeamArea（中间表）
	id,
	washer_team_id,
	area_id

问题复现

class WasherTeam extends Model
{

  public function areas(): BelongsToMany
  {  
     return $this->belongsToMany(VehicleLocationArea::class, WasherTeamArea::class, 'washer_team_id', 'area_id');
  }

}

当执行

$areas = WasherTeam::query()->find(1)->areas->pluck('name', 'id');

$areas 获取的 id 一直是中间表 WasherTeamArea 的 id。无法获得实际想获取的 VehicleLocationArea id。

问题原因

通过追踪执行的 sql 语句，执行结果如下

select
  *,
  ST_AsText(lat_lng) as lat_lng,
  `washer_team_areas`.`washer_team_id` as `pivot_washer_team_id`,
  `washer_team_areas`.`area_id` as `pivot_area_id`
from
  `vehicle_location_areas`
  inner join `washer_team_areas` on `vehicle_location_areas`.`id` = `washer_team_areas`.`area_id`
where
  `washer_team_areas`.`washer_team_id` = 1

开始我怀疑是 laravel orm 自身内连查询 select * ... 导致查询表的 id ，被中间表覆盖。后面发现 Model VehicleLocationArea 存在如下代码导致 id 被覆盖：

public function newQuery()
{
  $raw = 'ST_AsText(lat_lng) as lat_lng ';
  return parent::newQuery()->addSelect('*', DB::raw($raw));
}

解决办法

加上表名前缀

public function newQuery()
{
  $raw = 'ST_AsText(lat_lng) as lat_lng';
  return parent::newQuery()->addSelect("{$this->getTable()}.*", DB::raw($raw));
}