Mybatis报错：There is no getter for property named ‘xxx‘ in ‘class xxx 的解决办法

在mybatis中遇到这样的报错，There is no getter for property named ‘xxx’ in 'class xxx ，这篇博客给出了解决办法。

1. 错误信息

1.1 控制台报错信息

org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'username' in 'class com.zxy.pojo.User'
### Cause: org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'username' in 'class com.zxy.pojo.User'

	at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:150)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141)
	at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:137)
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:75)
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:59)
	at com.sun.proxy.$Proxy5.findUserByVO(Unknown Source)
	at com.zxy.test.MybatisTest.testFindByVO(MybatisTest.java:154)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
	at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:30)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'username' in 'class com.zxy.pojo.User'
	at org.apache.ibatis.reflection.Reflector.getGetInvoker(Reflector.java:419)
	at org.apache.ibatis.reflection.MetaClass.getGetInvoker(MetaClass.java:164)
	at org.apache.ibatis.reflection.wrapper.BeanWrapper.getBeanProperty(BeanWrapper.java:162)
	at org.apache.ibatis.reflection.wrapper.BeanWrapper.get(BeanWrapper.java:49)
	at org.apache.ibatis.reflection.MetaObject.getValue(MetaObject.java:122)
	at org.apache.ibatis.reflection.MetaObject.getValue(MetaObject.java:119)
	at org.apache.ibatis.executor.BaseExecutor.createCacheKey(BaseExecutor.java:219)
	at org.apache.ibatis.executor.CachingExecutor.createCacheKey(CachingExecutor.java:146)
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:82)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:148)
	... 30 more

1.2 主要的错误信息

There is no getter for property named ‘username’ in ‘class com.zxy.pojo.User’

2. 解决错误

1. 最先想着是不是User实体类没有写 Getter and Setter 方法，可是发现写了。

 <select id="pageQuery" resultType="com.sky.vo.DishVO">
        select d.*, c.name as categoryName from dish d left outer join category c on d.category_id = c.id
        <where>
            <if test="name != null">
                and d.name like concat('%', #{name}, '%')
            </if>
            <if test="categoryId != null">
                and d.category_id= #{categoryId}
            </if>
            <if test="status != null">
                and d.status = #{status}
            </if>
        </where>
        order by d.create_time desc
    </select>

2. 发现数据库表字段category_id与实体类属性categoryId不一致

<if test="category_id != null">
    and d.category_id= #{categoryId}
</if>

修改后：

<if test="categoryId != null">
    and d.category_id= #{categoryId}
</if>

注意：在遇到这个错误的时候一定要 检查你的实体类中的属性名是否和要映射的数据库表中的字段名字一致。sql 语句的内容不区分大小写，如果不是 sql 语句的内容一定要区分大小写。

3. Reference

https://blog.csdn.net/weixin_43570367/article/details/103546365