在使用MyBatis时,遇到这样的问题:
org.apache.ibatis.ognl.OgnlException: source is null for getProperty(null, "name")] with root cause
<select id="getTotal" resultType="java.lang.Long">
select count(*) from employee e
<where>
<!--<if test="emp !=null">-->
<if test="emp.name != null and emp.name!=''">
and e.name like concat('%',#{emp.name},'%')
</if>
<if test="emp.politicId != null">
and e.politicId =#{emp.politicId}
</if>
<if test="emp.jobLevelId != null">
and e.jobLevelId =#{emp.jobLevelId}
</if>
<if test="emp.posId != null">
and e.posId =#{emp.posId}
</if>
<if test="emp.nationId != null">
and e.nationId =#{emp.nationId}
</if>
<if test="emp.departmentId != null">
and e.departmentId =#{emp.departmentId}
</if>
<if test="emp.engageForm != null">
and e.engageForm =#{emp.engageForm}
</if>
<if test="beginDateScope !=null">
and emp.beginDate between #{beginDateScope[0]} and #{beginDateScope[1]}
</if>
<!--</if>-->
</where>
</select>
我在Mapper接口中定义了getTotal方法,在Service中调用这个方法,方法中需要传入一个Employee对象(在mapper中使用@Param注解取别名emp),我在调用时传入的值为null.
报错:
Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.builder.BuilderException: Error evaluating expression 'emp.name != null and emp.name!='''. Cause: org.apache.ibatis.ognl.OgnlException: source is null for getProperty(null, "name")] with root cause
org.apache.ibatis.ognl.OgnlException: source is null for getProperty(null, "name")
经过谷歌发现,这个异常是MyBatis封装的,类似空指针异常,xml其实是Mapper接口的一个实现类,当一个为null的对象传入后,在xml的方法中使用这个值,就报这个错
可以在xml中增加对emp对象的判空语句,就是在上文中注释掉的xml语句,更改后,如果emp为null,就不执行where语句