GenGroupMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.pig4cloud.pig.codegen.mapper.GenGroupMapper">

  <resultMap id="genGroupMap" type="com.pig4cloud.pig.codegen.util.vo.GroupVo">
        <id property="id" column="group_id"/>
        <result property="groupName" column="group_name"/>
        <result property="groupDesc" column="group_desc"/>
	    <collection property="templateList" ofType="com.pig4cloud.pig.codegen.entity.GenTemplateEntity"
                    select="com.pig4cloud.pig.codegen.mapper.GenTemplateMapper.listTemplateById" column="group_id">
	    </collection>
  </resultMap>

	<select id="getGroupVoById" resultMap="genGroupMap">
	    SELECT
        g.id as group_id ,
        g.group_name ,
        g.group_desc
		FROM
		gen_group g
		WHERE g.id = #{id}

	</select>

</mapper>