thinkphp5.1 数据库查询多条件时使用索引数组并含有or的查询

如题，我希望的查询是这样的

SELECT * FROM `bus_product` WHERE name like '%keyword%' and  ( `department_id` = 6 or `department_id` IS NULL )

使用索引数组查询时，只需要这样设置

$map[] = ['no|name|season|remark', 'like', "%{$data['keyword']}%"];

//这里是重点
$map[] = ['department_id',['eq',$this->user->department],['null',''] , 'or'];

就能够达到要求啦！