Mybatis的collection获取以,分隔的id(There is no getter for property named ‘**‘ in ‘class java.lang.String‘)

约定不等于承诺〃 2021-09-07 06:04 152阅读 0赞

## 1.获取ids ##

sql使用group by 进行分组的时候查找该组的id只会返回一个，只需使用group\_concat(id)即可以获得该组的所有id。  
cast(created\_time AS date) 可获取年月日并分组排序  
**以下代码都是简化的逻辑代码，因为不能涉及到公司数据，切勿以为写的没有实际意义**

<select id="select*****Page" resultMap="User******Map">
       select group_concat(note_id) ids ,cast(created_time AS date) date_time 
        from  note 
       where  img_urls != ''
         GROUP BY cast(created_time AS date)
         ORDER BY cast(created_time AS date) DESC
     </select>

获取到的ids是以","分隔的字符串

## 2.通过ids获取数据列表 ##

对象映射

将ids传递给封装对象列表的方法时报错  
There is no getter for property named ‘\*\*’ in ‘class java.lang.String’

<select id="selecet***Ids" resultType="java.lang.String">
      SELECT *
      FROM note a
      WHERE a.note_id in
      <foreach item="item" index="index" collection="ids.split(',')" open="(" separator="," close=")">#{ item}</foreach>
            and a.img_urls != ''
     </select>

将ids替换成\*\*\_parameter\*\*解决问题  
如果只有一个参数，那么\_parameter 就代表该参数，如果有多个参数，那么\_parameter 可以get(0)得到第一个参数。

<select id="selecet***Ids" resultType="java.lang.String">
      SELECT *
      FROM note a
      WHERE a.note_id in
      <foreach item="item" index="index" collection="_parameter.split(',')" open="(" separator="," close=")">#{ item}</foreach>
            and a.img_urls != ''
     </select>