• Mybatis多表关联查询字段值覆盖问题


    错误展示

    • 多表关联查询的返回结果集
    	<resultMap id="specialdayAndWorktimeMap type="com.hierway.resm.domain.manage.timeSchedule.SpecialDayWorkTimeVO">  
      		<id column="special_date_id" property="specialDateId"/>
     		<result column="name" property="name"/>
      		<result column="date" property="date"/>
      		<result column="type" property="type"/>
      		<result column="start_time" property="startTime"/>
      		<result column="end_time" property="endTime"/>
      		<collection property="workTimeList" ofType="com.hierway.resm.domain.manage.timeSchedule.WorkTime">
        		<id column="work_time_id" property="workTimeId"/>
        		<result column="start_time" property="startTime"/>
       			<result column="end_time" property="endTime"/>
      		</collection>
    	</resultMap>  
    

    上面的映射中,返回结果类:SpecialDayWorkTimeVO中定义了7个属性,其中第7个属性是关联查询一对多的对象List

    可以看到在workTime中的属性startTime与endTime和上面的startTime与endTime属性名相同。

    • 查询语句展示
    	<select id="getSpecialDayAndWorkTimesByPuId" resultMap="specialdayAndWorktimeMap">
    	  SELECT sd.special_date_id,sd.name,sd.type,sd.date,sd.start_time,sd.end_time,wt.work_time_id,wt.start_time,wt.end_time
    	 FROM powerunit_specialday_relation AS psr
    	  LEFT JOIN special_day AS sd ON psr.special_date_id = sd.special_date_id
    	 LEFT JOIN specailday_worktime_relation AS swr ON sd.special_date_id = swr.special_date_id
    	 LEFT JOIN work_time AS wt ON swr.work_time_id = wt.work_time_id
    	 WHERE psr.pu_id = #{puId}
    	</select>
    

    在junit中进行mapper层测试,原本数据库中只有一条SpecialDay的记录,并没有关联的WorkTime记录,那么理想的结果是返回的VO对象中
    specialDay相关的属性有值,而List是一个长度为0的List。可是测试结果转为Json格式如下所示:

    [{"specialDateId":2,"name":"b","date":"2019-04-27","type":0,"startTime":"5:00","endTime":"17:00","workTimeList":[{"workTimeId":null,"startTime":"5:00","endTime":"17:00"}]}]
    

    可以看到,list中含有一条数据,且前面的属性,覆盖了后面具有相同属性名的WorkTime中的startTime与endTime值,结果与测试结果不符合。

    解决方案

    • 给workTime表查询结果设置一个区分的别名,同时修改resultMap中标签下的对应的字段名(column元素),展示如下:
    	<resultMap id="specialdayAndWorktimeMap" type="com.hierway.resm.domain.manage.timeSchedule.SpecialDayWorkTimeVO">
    	    <id column="special_date_id" property="specialDateId"/>
    	    <result column="name" property="name"/>
    	    <result column="date" property="date"/>
    	    <result column="type" property="type"/>
    	    <result column="start_time" property="startTime"/>
    	    <result column="end_time" property="endTime"/>
    	    <collection property="workTimeList" ofType="com.hierway.resm.domain.manage.timeSchedule.WorkTime">
    	      <id column="work_time_id" property="workTimeId"/>
    	      <result column="wstart_time" property="startTime"/>
    	      <result column="wend_time" property="endTime"/>
    	    </collection>
    	  </resultMap>  
    
    	 <!--List<SpecialDayWorkTimeVO> getSpecialDayAndWorkTimesByPuId(Integer puId);-->
    	 <select id="getSpecialDayAndWorkTimesByPuId" resultMap="specialdayAndWorktimeMap">
    	    SELECT sd.special_date_id,sd.name,sd.type,sd.date,sd.start_time,sd.end_time,wt.work_time_id,wt.start_time AS wstart_time ,wt.end_time AS wend_time
    	    FROM powerunit_specialday_relation AS psr
    	    LEFT JOIN special_day AS sd ON psr.special_date_id = sd.special_date_id
    	 LEFT JOIN specailday_worktime_relation AS swr ON sd.special_date_id = swr.special_date_id
    	 LEFT JOIN work_time AS wt ON swr.work_time_id = wt.work_time_id
    	 WHERE psr.pu_id = #{puId}
    	</select>
    
    • 相同测试数据如下:
    [{"specialDateId":2,"name":"b","date":"2019-04-27","type":0,"startTime":"5:00","endTime":"17:00","workTimeList":[]}]  
    

    此次测试结果正确!workTimeList长度为0。

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  • 原文地址:https://www.cnblogs.com/yiweiblog/p/10775968.html
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