想要确保用户名是唯一的

【问题标题】：Want to make sure the Username is unique想要确保用户名是唯一的
【发布时间】：2021-07-21 12:49:03
【问题描述】：

我正在尝试向我的 Spring Boot 应用程序添加一个小功能，我希望用户名是唯一的，因为我正在调用我的 get List Students 方法并检查新添加的用户名是否与任何其他用户名匹配，那么它应该给用户一个错误，因为我收到antlr.NoViableAltException: unexpected token: s 的错误请在这里帮助我我做错了什么，最好的做法是什么.. 这是我的代码：

GetListOfStudents：

@SuppressWarnings("unchecked")
    @Override
    @Transactional
    public List<Student> getListOfStudent(Student studentModel) {
        List<Student> students =null;
        try {
            
            StringBuilder stringBuild = new StringBuilder("SELECT s FROM Student s WHERE s.id !=0 AND s.status="+Constants.StudentStatus.ACTIVE);
            if(studentModel !=null) {
                if(studentModel.getId()!=null) {
                    stringBuild.append("AND s.id =:id");
                }
                if(studentModel.getCourse()!=null) {
                    stringBuild.append("AND s.course =:course");
                }
                if(studentModel.getFirstName()!=null) {
                    stringBuild.append("AND s.firstName =:firstName");
                }
                if(studentModel.getLastName()!=null) {
                    stringBuild.append("AND s.lastName =:lastName");
                }
                if(studentModel.getEmail()!=null) {
                    stringBuild.append("AND s.email =:email");
                }
                if(studentModel.getDateOfBirth()!=null) {
                    stringBuild.append("AND s.dateOfBirth =:dateOfBirth");
                }
                if(studentModel.getStatus()!=null) {
                    stringBuild.append("AND s.status =:status");
                }
                if(studentModel.getAddedAt()!=null) {
                    stringBuild.append("AND s.addedAt =:addedAt");
                }
                if(studentModel.getUserName()!=null) {
                    stringBuild.append("AND s.userName =:userName");
                }
                if(studentModel.getPassword()!=null) {
                    stringBuild.append("AND s.password =:password");
                }
                if(studentModel.getUserType()!=null) {
                    stringBuild.append("AND s.userType =:userType");
                }
            }else {
                throw new Exception("Model is null  ===================" );
            }
            Query query = entityManage.createQuery(stringBuild.toString());
            
            if(studentModel !=null) {
                if(studentModel.getId()!=null) {
                    query.setParameter("id", studentModel.getId());
                }
                if(studentModel.getCourse()!=null) {
                    query.setParameter("course", studentModel.getCourse());
                }
                if(studentModel.getFirstName()!=null) {
                    query.setParameter("firstName", studentModel.getFirstName());
                }
                if(studentModel.getLastName()!=null) {
                    query.setParameter("lastName", studentModel.getLastName());
                }
                if(studentModel.getEmail()!=null) {
                    query.setParameter("email", studentModel.getEmail());
                }
                if(studentModel.getDateOfBirth()!=null) {
                    query.setParameter("dateOfBirth", studentModel.getDateOfBirth());
                }
                if(studentModel.getStatus()!=null) {
                    query.setParameter("status", studentModel.getStatus());
                }
                if(studentModel.getAddedAt()!=null) {
                    query.setParameter("addedAt", studentModel.getAddedAt());
                }
                if(studentModel.getUserName()!=null) {
                    query.setParameter("userName", studentModel.getUserName());
                }
                if(studentModel.getPassword()!=null) {
                    query.setParameter("password", studentModel.getPassword());
                }
                if(studentModel.getUserType()!=null) {
                    query.setParameter("userType", studentModel.getUserType());
                }
            }
            students = query.getResultList();
        }catch(Exception exe) {
            exe.printStackTrace();
        }
//      LOGGER.info("Students are : " + students);
        return students;
    }

StudentController（我正在尝试检查用户名）

@RequestMapping(value="/saveStudent",method = {RequestMethod.POST,RequestMethod.GET})
    public String SaveStudent(@ModelAttribute("studentFormData") Student student,BindingResult errorList) {
        List<Student> students= new ArrayList<Student>();
        try {
            students =studentService.getListOfStudent(student);
            
            for(Student sts: students ) {
                LOGGER.info("STUDENTS USER NAME :::::::::::::::::::::::" + sts.getUserName());
                if(sts.getUserName().equals(student.getUserName())) {
//                  errorList.addError(new ObjectError("error" , " Username is already taken try this user name " + utils.RandomAlphaString()));
                    LOGGER.info("USER NAME  MATCHED _______________________________________________________________________");
                    errorList.rejectValue("userName", "User name is already in use try with this username : "+ Utils.RandomAlphaString());
                }
            }
            studentService.SaveStudent(student);
            if(errorList.hasErrors()) {
                return "student/studentForm";
            }
        } catch (Exception e) {
            e.printStackTrace();
        }       
        return "redirect:/Students/list";
    }

控制台：

    antlr.NoViableAltException: unexpected token: s
    at org.hibernate.hql.internal.antlr.HqlBaseParser.queryRule(HqlBaseParser.java:864) [hibernate-core-5.4.30.Final.jar:5.4.30.Final]
    at org.hibernate.hql.internal.antlr.HqlBaseParser.selectStatement(HqlBaseParser.java:336) [hibernate-core-5.4.30.Final.jar:5.4.30.Final]
    at org.hibernate.hql.internal.antlr.HqlBaseParser.statement(HqlBaseParser.java:200) [hibernate-core-5.4.30.Final.jar:5.4.30.Final]
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.parse(QueryTranslatorImpl.java:294) [hibernate-core-5.4.30.Final.jar:5.4.30.Final]
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:189) [hibernate-core-5.4.30.Final.jar:5.4.30.Final]
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:144) [hibernate-core-5.4.30.Final.jar:5.4.30.Final]
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:113) [hibernate-core-5.4.30.Final.jar:5.4.30.Final]
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:73) [hibernate-core-5.4.30.Final.jar:5.4.30.Final]
    at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:162) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]
    at org.hibernate.internal.AbstractSharedSessionContract.getQueryPlan(AbstractSharedSessionContract.java:613) ~[hibernate-core-5.4.30.Final.jar:5.4.30.Final]


java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: unexpected token: s near line 1, column 116 [SELECT s FROM com.Library.LibraryManagement.Entity.Student s WHERE s.id !=0 AND s.status=0AND s.course =:courseAND s.firstName =:firstNameAND s.lastName =:lastNameAND s.email =:emailAND s.dateOfBirth =:dateOfBirthAND s.userName =:userNameAND s.password =:passwordAND s.userType =:userType]
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:138)
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:181)
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:188)
    at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:734)
    at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:114)
    at jdk.internal.reflect.GeneratedMethodAccessor109.invoke(Unknown Source)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:362)
    at com.sun.proxy.$Proxy94.createQuery(Unknown Source)
    at jdk.internal.reflect.GeneratedMethodAccessor109.invoke(Unknown Source)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:311)
    at com.sun.proxy.$Proxy94.createQuery(Unknown Source)
Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException: unexpected token: s near line 1, column 116 [SELECT s FROM com.Library.LibraryManagement.Entity.Student s WHERE s.id !=0 AND s.status=0AND s.course =:courseAND s.firstName =:firstNameAND s.lastName =:lastNameAND s.email =:emailAND s.dateOfBirth =:dateOfBirthAND s.userName =:userNameAND s.password =:passwordAND s.userType =:userType]
    at org.hibernate.hql.internal.ast.QuerySyntaxException.convert(QuerySyntaxException.java:74)
    at org.hibernate.hql.internal.ast.ErrorTracker.throwQueryException(ErrorTracker.java:93)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.parse(QueryTranslatorImpl.java:301)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:189)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:144)
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:113)
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:73)
    at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:162)
    at org.hibernate.internal.AbstractSharedSessionContract.getQueryPlan(AbstractSharedSessionContract.java:613)
    at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:725)
    ... 128 more
org.springframework.transaction.UnexpectedRollbackException: Transaction silently rolled back because it has been marked as rollback-only
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:752)
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:711)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:654)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:407)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:750)
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:692)
    at com.Library.LibraryManagement.Serviceimpl.StudentServiceImpl$$EnhancerBySpringCGLIB$$9986e406.getListOfStudent(<generated>)
    at com.Library.LibraryManagement.Controller.StudentController.SaveStudent(StudentController.java:66)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:197)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:141)
    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:894)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1060)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:962)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:652)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:327)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:115)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:81)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:119)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:126)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:81)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:105)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:149)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.base/java.lang.Thread.run(Thread.java:844)

【问题讨论】：

  • 只查询学生表以获取特定用户名并查看它是否已经存在而不是查询所有学生并比较所有学生（如果发生这种情况）会不会更容易？似乎它也会减少导致查询语法问题的事情。

标签： java spring spring-boot jpa exception


【解决方案1】：

我建议您 - 采用另一种方法来完成这项工作。

对数据库表中的用户名列应用唯一约束。

以下是如何设置唯一约束的示例：

ALTER TABLE Students
ADD CONSTRAINT UC_Username UNIQUE (Username);

更多详情可以参考：https://www.w3schools.com/sql/sql_unique.asp

在保存新对象时，如果抛出异常，那么您可以简单地取消/事务。

不推荐编写额外的代码来检查用户名是否存在。只需使用数据库功能。它不仅服务于您的目的，而且还提高了您的数据库验证的质量。

【讨论】：

  • 我确实已经应用了唯一约束，但我只是想检查用户是否存在，但我认为这不是最好的方法，感谢您的输入
【解决方案2】：

a) SELECT s FROM Student s - 这甚至让我感到困惑。 select * from ...

b) 当你在做stringBuild.append("AND s.id =:id"); 时，你需要允许空格，所以改为

stringBuild.append(" AND s.id =:id ");

最后使用 NativeQuery

Query query = entityManage.createNativeQuery(stringBuild.toString());

【讨论】：

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