一个简单的查询,mapper文件的配置如下:

<select id="querySupplierAndDriverId" resultType="com.zhuanche.entity.mdbcarmanage.DriverInfoInterCity">
  select  driver_id ,city_id ,supplier_id  
  from driver_info_inter_city
  where driver_id IN
  <foreach collection="driverIds" open="(" close=")" separator="," item="driverId" >
    #{driverId}
  </foreach>
  AND  status = 1
</select>

结果在使用的时候,一直报空指针异常。但是看了下数据库里面也能查询到数据,怎么就空指针了呢?

 最后想了下,是这个查询 的结果和resultType的字段没有匹配一块导致的,没有查询出来,按照我的理解,应该是会new 一个对象的,但是应该是没有。先把问题改了

 

  <select id="querySupplierAndDriverId" resultType="com.zhuanche.entity.mdbcarmanage.DriverInfoInterCity">
    select  driver_id as driverId,city_id as cityId,supplier_id as supplierId
    from driver_info_inter_city
    where driver_id IN
    <foreach collection="driverIds" open="(" close=")" separator="," item="driverId" >
      #{driverId}
    </foreach>
    AND  status = 1
  </select>

有空研究下源码

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