Mybatis 使用discriminator鉴别器映射

碰见的问题场景：需要根据查询出来的字段的值，分别设置两个不同的字段。这是一个类似java的case when的一个判断。

通过查找相关的资料，知道discriminator可以进行设置，相关的代码如下：

<resultMap id="BaseResultMap" type="com.onlyou.ai.autobt.repository.vo.SampleVO">
    <id column="id" jdbcType="BIGINT" property="id" />
    <result column="task_id" jdbcType="BIGINT" property="taskId" />
    <result column="sample_path" jdbcType="VARCHAR" property="samplePath" />
    <result column="source_path" jdbcType="VARCHAR" property="sourcePath" />
    <result column="source_name" jdbcType="VARCHAR" property="sourceName" />
    <result column="final_value_status" jdbcType="VARCHAR" property="finalValueStatus" />
    <result column="sample_detail_list_hash" jdbcType="VARCHAR" property="sampleDetailListHash" />
    <result column="status" jdbcType="VARCHAR" property="status" />
    <result column="template_no" jdbcType="VARCHAR" property="templateNo" />
    <result column="sample_hash" jdbcType="VARCHAR" property="sampleHash" />
    <result column="from_sample_id" jdbcType="BIGINT" property="fromSampleId" />
    <result column="type" jdbcType="VARCHAR" property="type" />
  </resultMap>


  <resultMap id="sampleDetailListMapSelect"
             type="com.onlyou.ai.autobt.repository.vo.SampleVO">
    <collection property="sampleDetailList" javaType="ArrayList" column="{sampleId=id}"
       ofType="com.onlyou.ai.autobt.repository.vo.SampleDetailVO"
        select="com.onlyou.ai.autobt.repository.mapper.ISampleDetailMapper.selectSampleDetailList">
    </collection>
  </resultMap>
  <resultMap id="subImageListMapSelect"
             type="com.onlyou.ai.autobt.repository.vo.SampleVO">
    <collection property="subImageList" javaType="ArrayList" column="{sampleId=id}"
                ofType="com.onlyou.ai.autobt.repository.vo.SubImageVO"
                select="com.onlyou.ai.autobt.repository.mapper.ISubImageMapper.selectSubImageList">
    </collection>
  </resultMap>
  <resultMap id="sampleAssociation" type="com.onlyou.ai.autobt.repository.vo.SampleVO" extends="BaseResultMap">
    <discriminator javaType="String" column="type">
      <case value="0" resultMap="sampleDetailListMapSelect">
      </case>
      <case value="1" resultMap="subImageListMapSelect">
      </case>
    </discriminator>

  </resultMap>
  <sql id="Base_Column_List">
    id, task_id, sample_path, source_path, source_name, final_value_status, sample_detail_list_hash, 
    status, template_no, sample_hash, from_sample_id,type
  </sql>
  <select id="selectSampleList" parameterType="map" resultMap="sampleAssociation">
    select
    <include refid="Base_Column_List" />
    from t_sample where 1 = 1
    <if test="taskId!=null">
      AND task_id = #{taskId}
    </if>
    <if test="sampleStatus!=null and sampleStatus != ''">
      AND status = #{sampleStatus}
    </if>
  </select>

结果集映射，如果type的值为0 则查询sampleDetailList ，如果为1 则设置subImageList。

其中：

select="com.onlyou.ai.autobt.repository.mapper.ISampleDetailMapper.selectSampleDetailList"是另外一个xml的查询语句，

ofType="com.onlyou.ai.autobt.repository.vo.SampleDetailVO" 是返回的list的元素的类型

 

参考：https://www.cnblogs.com/zwwhnly/p/11212396.html