mybatis如何处理返回实体类屏蔽null

Question

sql和配置 添加callSettersOnNulls这个属性没起作用

 <select id="selectClassIdByUserId" resultType="entity.SysClass" parameterType="java.lang.Long">
    select tc.class_id,c.`name` from(
    select * from sys_teacher where user_id = #{user_id,jdbcType=BIGINT}) t left join 
    sys_teacher_class_subject tc on t.id = tc.teacher_id 
    left join sys_class c ON tc.class_id = c.id
    where c.`status` = 1
  </select>
<settings>
        <setting name="cacheEnabled" value="true" />  
        <setting name="lazyLoadingEnabled" value="true" />  
        <setting name="multipleResultSetsEnabled" value="true" />  
        <setting name="useColumnLabel" value="true" />  
        <setting name="useGeneratedKeys" value="false" />
        <setting name="defaultExecutorType" value="SIMPLE" />  
        <setting name="callSettersOnNulls" value="true" />  
    </settings>

返回的LIST

List<SysClass> classList = classs.selectClassIdByUserId(Long.parseLong(uid));结果如下：

  [SysClass [id=null, name=小学二年级（1）班, schoolId=null, school=null, gradeId=null, remark=null, academicYear=null, status=null, chargeTeacherId=null, grade=null, chargeTeacher=null, students=null], SysClass [id=null, name=小学二年级（2）班, schoolId=null, school=null, gradeId=null, remark=null, academicYear=null, status=null, chargeTeacherId=null, grade=null, chargeTeacher=null, students=null]]

Answer 1

你查询返回的是实体类，但Sql只查询2个字段，其他没查询的字段默认值就是null，如果不想为null，那就赋值为空串，就是""