Mybatis多个集合的迭代处理

淩亂°似流年 2022-05-23 13:07 197阅读 0赞

在使用这个功能是需要特别注意以下规则：

1. 当查询的参数只有一个时

A. 如果参数的类型是List, 则在使用时，collection属性要必须指定为 list

findByIds(List<Long> ids)

<select id="findByIdsMap" resultMap="BaseResultMap">
             Select
             <include refid="Base_Column_List" />
             from sys_user where user_id in
                      <foreach item="item" index="index" collection="list"
                             open="(" separator="," close=")">
                            #{item}
                    </foreach>
      </select>

B. 如果参数的类型是Array,则在使用时，collection属性要必须指定为 array

findByIds(Long\[\] ids)

<select id="findByIdsMap" resultMap="BaseResultMap">
                     select
                     <include refid="Base_Column_List" />
              from sys_user where user_id in
                      <foreach item="item" index="index" collection="array"
                             open="(" separator="," close=")">
                            #{item}
                    </foreach>
      </select>

2、

当查询的参数有多个时,例如 findByIds(String name, Long\[\] ids)//这种方式不推荐使用

这种情况需要特别注意，在传参数时，一定要改用Map方式, 这样在collection属性可以指定名称

下面是一个示例

Map<String, Object> params = new HashMap<String, Object>(2);
            params.put("name", name);
             params.put("shxt", ids);
            mapper.findByIdsMap(params);
     
        <select id="findByIdsMap" resultMap="BaseResultMap">
                     select
                     <include refid="Base_Column_List" />
              from sys_user where user_id in
                      <foreach item="item" index="index" collection="shxt"
                             open="(" separator="," close=")">
                            #{item}
                    </foreach>
       </select>

3、本人实际使用例子

@Override
        public List<PointsSummaryForMonths> pointsForPduMonthForIN() {
    
            List<CustomPdu> list = customPduMapper.getPidFromCustomPdu();
            List<Integer> list1 = new ArrayList<>();
            for (int i = 0; i < list.size(); i++) {
                int pduId = list.get(i).getPid();
                list1.add(pduId);
            }
    
            List<String> list2=DateUtil.getMonthList();
            Map<String, Object> pduIdMap = new HashMap<>();
            pduIdMap.put("listone", list1);
            pduIdMap.put("listtwo",list2);
    
            //Map<String,Object> monthMap=new HashMap<>();
            //  monthMap= DateUtil.getDateMap();
            return pointsSummaryForMonthsMapper.pointsForPduMonthForIN(pduIdMap);
        }

List<PointsSummaryForMonths> pointsForPduMonthForIN(Map map);

WHERE
    	jira.PROJECT in
         <foreach collection="listone" index="index" item="item" open="(" close=")" separator=",">
            #{item}
        </foreach>
        AND it.ID IN ("10001", "10102", "10100")
    AND jira.issuestatus = "10001"
    GROUP BY  pro.pname,
    	date_format(doneTable.doneDate, '%Y-%m'))as tabletwo
        where tabletwo.month in
            <foreach collection="listtwo" index="index" item="item" open="(" close=")" separator=",">
                #{item}
            </foreach>
      </select>