成功解决org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.reflection.ReflectionException: There is no getter for property named ‘ew’ in ‘class com.baomidou.mybatisplus.core.conditions.query.QueryWrapper’

org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'ew' in 'class com.baomidou.mybatisplus.core.conditions.query.QueryWrapper'
	at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:77)
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:446)
	at com.sun.proxy.$Proxy105.update(Unknown Source)
	at org.mybatis.spring.SqlSessionTemplate.update(SqlSessionTemplate.java:294)
	at com.baomidou.mybatisplus.core.override.PageMapperMethod.execute(PageMapperMethod.java:73)
	at com.baomidou.mybatisplus.core.override.PageMapperProxy.invoke(PageMapperProxy.java:64)
	at com.sun.proxy.$Proxy106.delete(Unknown Source)
	at com.atguigu.eduservice.service.impl.EduChapterServiceImpl.removeByCourseId(EduChapterServiceImpl.java:103)
	at com.atguigu.eduservice.service.impl.EduChapterServiceImpl$$FastClassBySpringCGLIB$$c5625433.invoke(<generated>)
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:685)
	at com.atguigu.eduservice.service.impl.EduChapterServiceImpl$$EnhancerBySpringCGLIB$$e9c968f3.removeByCourseId(<generated>)
	at com.atguigu.eduservice.service.impl.EduCourseServiceImpl.removeCourse(EduCourseServiceImpl.java:159)
	at com.atguigu.eduservice.service.impl.EduCourseServiceImpl$$FastClassBySpringCGLIB$$e8a30daf.invoke(<generated>)
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:685)
	at com.atguigu.eduservice.service.impl.EduCourseServiceImpl$$EnhancerBySpringCGLIB$$409d62e7.removeCourse(<generated>)
	at com.atguigu.eduservice.controller.EduCourseController.deleteCourse(EduCourseController.java:118)
	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.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:888)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793)
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
	at org.springframework.web.servlet.FrameworkServlet.doDelete(FrameworkServlet.java:931)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:666)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:861)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1579)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)
Caused by: org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'ew' in 'class com.baomidou.mybatisplus.core.conditions.query.QueryWrapper'
	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.scripting.xmltags.DynamicContext$ContextMap.get(DynamicContext.java:94)
	at org.apache.ibatis.scripting.xmltags.DynamicContext$ContextAccessor.getProperty(DynamicContext.java:108)
	at org.apache.ibatis.ognl.OgnlRuntime.getProperty(OgnlRuntime.java:2685)
	at org.apache.ibatis.ognl.ASTProperty.getValueBody(ASTProperty.java:114)
	at org.apache.ibatis.ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212)
	at org.apache.ibatis.ognl.SimpleNode.getValue(SimpleNode.java:258)
	at org.apache.ibatis.ognl.ASTNotEq.getValueBody(ASTNotEq.java:50)
	at org.apache.ibatis.ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212)
	at org.apache.ibatis.ognl.SimpleNode.getValue(SimpleNode.java:258)
	at org.apache.ibatis.ognl.Ognl.getValue(Ognl.java:470)
	at org.apache.ibatis.ognl.Ognl.getValue(Ognl.java:434)
	at org.apache.ibatis.scripting.xmltags.OgnlCache.getValue(OgnlCache.java:44)
	at org.apache.ibatis.scripting.xmltags.ExpressionEvaluator.evaluateBoolean(ExpressionEvaluator.java:32)
	at org.apache.ibatis.scripting.xmltags.IfSqlNode.apply(IfSqlNode.java:34)
	at org.apache.ibatis.scripting.xmltags.MixedSqlNode.apply(MixedSqlNode.java:33)
	at org.apache.ibatis.scripting.xmltags.DynamicSqlSource.getBoundSql(DynamicSqlSource.java:41)
	at org.apache.ibatis.mapping.MappedStatement.getBoundSql(MappedStatement.java:292)
	at org.apache.ibatis.executor.statement.BaseStatementHandler.<init>(BaseStatementHandler.java:64)
	at org.apache.ibatis.executor.statement.PreparedStatementHandler.<init>(PreparedStatementHandler.java:40)
	at org.apache.ibatis.executor.statement.RoutingStatementHandler.<init>(RoutingStatementHandler.java:46)
	at org.apache.ibatis.session.Configuration.newStatementHandler(Configuration.java:558)
	at org.apache.ibatis.executor.SimpleExecutor.doUpdate(SimpleExecutor.java:48)
	at org.apache.ibatis.executor.BaseExecutor.update(BaseExecutor.java:117)
	at org.apache.ibatis.executor.CachingExecutor.update(CachingExecutor.java:76)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:198)
	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.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:433)
	... 66 more
2020-11-20 12:51:19 |INFO  |PollingServerListUpdater-0 |ChainedDynamicProperty.java:115 |com.netflix.config.ChainedDynamicProperty |Flipping property: service-vod.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647

在这里插入图片描述

问题描述：在使用mybatis-plus框架开发时，通过QueryWrapper操作数据库，测试时出现问题。
解决思考：
- 分析：在上述报错信息中，我们关注第一部分第一句，或者cause by那句

Caused by: org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'ew' in 'class com.baomidou.mybatisplus.core.conditions.query.QueryWrapper'

这句话说QueryWrapper没有‘ew’属性的方法
此时我们可能会去该类看看，但发现不是这个问题，因为之前用得好好的，而且我的mybatis-plus版本应该是稳定版本，应该不是querywrapper的bug（虽然可能会是wrapper底层的bug）但我们应该首先排除自己写的代码有没有bug。所以我们转换思路想想，可能是我们使用错误之类的，没有按照规范使用啥的
我们去查看报错的代码段

在这里插入图片描述

第一个类 EduChapterServiceImpl （一般第一个类时错误的源头，也就是报错信息的最上面一个类）
第二个类：EduCourseServiceImpl
+ 第三个类 EduCourseController

三个之间的关系，EduCourseController调用EduCourseServiceImpl，
EduCourseServiceImpl调用EduChapterServiceImpl
我们发现，EduChapterServiceImpl 中querywrapper写错了,泛型没有写对，应该是educhapter。本来idea编译就没通过，当时太傻了，我是强行在mapper加了一个对应的方法

解决方法：修改wrapper的泛型，去掉mapper强行添加的方法

顺便看看其他小伙伴类似的报错信息如何解决的吧：

错误：我在实现类里面写业务逻辑的时候，两张表里面的数据使用了同一个模型接口去调用，导致mybatisPlus不能识别出来
在这里插入图片描述修改：属于本张表的就调用getBaseMapper()，调用其他表的就自己注入

总结

由于报错信息说的类是QueryWrapper没有‘ew’的getter方法，但这个类是框架里面的，我们应该难以搞定太底层的错误，加上mybatis-plus框架较为成熟，活跃程度还可以，很可能是我们的问题，不是querywrapper的问题。
查看报错的代码部分，分析类型对应关系是不是有问题，大概率是类型对应错了
主要是mapper使用的对应关系，wrapper的泛型有没有对应上等

原文链接：https://blog.csdn.net/weixin_43649997/article/details/109845873