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Putting Database call inside `isvalid()` method of custom ConstraintValidator is causing stackoverflow error because it is being called repeatedly

This is not the same problem as this. Following the answer here, if I add spring.jpa.properties.javax.persistence.validation.mode=none then my custom validator is not even invoked.
Use Case
My Table has 3 columns - id, role and user_id. Now there can be only 1 row for which role can take the value ROLE_ROOT. And once that record is inserted, it can't be updated.
How I am trying to implement
Using custom javax.validation.ConstraintValidator and checking if record is present for role=ROLE_ROOT inside isValid
(I know there are alternatives to do this. like, before calling repository.save(..), call repository.findByRole(..) , check and restrict. But I want to understand why this scenario is failing.)
What error I am getting
java.lang.StackOverflowError: null and the line ~~~~~~validation check is being printed hundreds of times.
My Code
MyController class
#RestController
public class MyController {
#Autowired
private MyTableRepository repository;
#GetMapping("/hello")
public void hello() {
MyEntity myEntity = new MyEntity();
myEntity.setId(123456);
myEntity.setRole("ROLE_ROOT");
myEntity.setUserId(3);
repository.save(myEntity);
}
}
MyRepository class
#Repository
public interface MyTableRepository extends JpaRepository<MyEntity, Integer> {
List<MyEntity> findByRole(String roleName);
}
MyEntity class
#Entity
#Table(name = "my_table")
public class MyEntity {
#Id
#Column(name = "id")
private int id;
#Column(name = "role")
#CheckRole
private String role;
#Column(name = "user_id")
private int userId;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getRole() {
return role;
}
public void setRole(String role) {
this.role = role;
}
public int getUserId() {
return userId;
}
public void setUserId(int userId) {
this.userId = userId;
}
}
My Custom Annotation
#Target({ FIELD, ANNOTATION_TYPE, METHOD, PARAMETER })
#Retention(RUNTIME)
#Constraint(validatedBy = RoleValidator.class)
public #interface CheckRole {
String message() default "{org.hibernate.validator.referenceguide.chapter06.CheckCase.message}";
Class<?>[] groups() default { };
Class<? extends Payload>[] payload() default { };
}
My Custom Validator class
public class RoleValidator implements ConstraintValidator<CheckRole, String> {
private final MyTableRepository repository;
public RoleValidator(MyTableRepository repository) {
this.repository = repository;
}
#Override
public void initialize(CheckRole constraintAnnotation) {
}
#Override
public boolean isValid(String value, ConstraintValidatorContext context) {
if(value.equals("ROLE_ROOT")){
System.out.println("~~~~~~validation check");
return (repository.findByRole("ROLE_ROOT").size() > 0);
}
else {
return true;
}
}
}
My ValidatorAddingCustomizer (following this question)
#Component
public class ValidatorAddingCustomizer implements HibernatePropertiesCustomizer {
private final ObjectProvider<Validator> provider;
public ValidatorAddingCustomizer(ObjectProvider<javax.validation.Validator> provider) {
this.provider = provider;
}
public void customize(Map<String, Object> hibernateProperties) {
Validator validator = provider.getIfUnique();
if (validator != null) {
hibernateProperties.put("javax.persistence.validation.factory", validator);
}
}
}
Hibernate validator version: 5.2.4.Final
Spring boot version: 2.3.1.RELEASE
Here is friendpaste link containing all the code.
A followup question on this is:
If I mark the id column of MyEntity as #GeneratedValue(strategy = GenerationType.IDENTITY) , with rest of the code intact, then the error changes to the below one
org.hibernate.AssertionFailure: null id in com.example.schooltimetable.entity.MyEntity entry (don't flush the Session after an exception occurs)
at org.hibernate.event.internal.DefaultFlushEntityEventListener.checkId(DefaultFlushEntityEventListener.java:76) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.event.internal.DefaultFlushEntityEventListener.getValues(DefaultFlushEntityEventListener.java:202) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.event.internal.DefaultFlushEntityEventListener.onFlushEntity(DefaultFlushEntityEventListener.java:162) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.event.internal.AbstractFlushingEventListener.flushEntities(AbstractFlushingEventListener.java:232) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.event.internal.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:92) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.event.internal.DefaultAutoFlushEventListener.onAutoFlush(DefaultAutoFlushEventListener.java:50) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:102) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.internal.SessionImpl.autoFlushIfRequired(SessionImpl.java:1325) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1405) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.query.internal.AbstractProducedQuery.doList(AbstractProducedQuery.java:1565) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.query.internal.AbstractProducedQuery.list(AbstractProducedQuery.java:1533) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.query.Query.getResultList(Query.java:165) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.query.criteria.internal.compile.CriteriaQueryTypeQueryAdapter.getResultList(CriteriaQueryTypeQueryAdapter.java:76) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.springframework.data.jpa.repository.query.JpaQueryExecution$CollectionExecution.doExecute(JpaQueryExecution.java:126) ~[spring-data-jpa-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.data.jpa.repository.query.JpaQueryExecution.execute(JpaQueryExecution.java:88) ~[spring-data-jpa-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.data.jpa.repository.query.AbstractJpaQuery.doExecute(AbstractJpaQuery.java:154) ~[spring-data-jpa-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.data.jpa.repository.query.AbstractJpaQuery.execute(AbstractJpaQuery.java:142) ~[spring-data-jpa-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor$QueryMethodInvoker.invoke(QueryExecutorMethodInterceptor.java:195) ~[spring-data-commons-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:152) ~[spring-data-commons-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:130) ~[spring-data-commons-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:80) ~[spring-data-commons-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:367) ~[spring-tx-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:118) ~[spring-tx-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:149) ~[spring-data-jpa-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:95) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at com.sun.proxy.$Proxy113.findByRole(Unknown Source) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:205) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at com.sun.proxy.$Proxy81.findByRole(Unknown Source) ~[na:na]
at com.example.schooltimetable.validator.RoleValidator.isValid(RoleValidator.java:53) ~[classes/:na]
at com.example.schooltimetable.validator.RoleValidator.isValid(RoleValidator.java:20) ~[classes/:na]
at org.hibernate.validator.internal.engine.constraintvalidation.ConstraintTree.validateSingleConstraint(ConstraintTree.java:448) ~[hibernate-validator-5.2.4.Final.jar:5.2.4.Final]
at org.hibernate.validator.internal.engine.constraintvalidation.ConstraintTree.validateConstraints(ConstraintTree.java:127) ~[hibernate-validator-5.2.4.Final.jar:5.2.4.Final]
at org.hibernate.validator.internal.engine.constraintvalidation.ConstraintTree.validateConstraints(ConstraintTree.java:87) ~[hibernate-validator-5.2.4.Final.jar:5.2.4.Final]
at org.hibernate.validator.internal.metadata.core.MetaConstraint.validateConstraint(MetaConstraint.java:73) ~[hibernate-validator-5.2.4.Final.jar:5.2.4.Final]
at org.hibernate.validator.internal.engine.ValidatorImpl.validateMetaConstraint(ValidatorImpl.java:617) ~[hibernate-validator-5.2.4.Final.jar:5.2.4.Final]
at org.hibernate.validator.internal.engine.ValidatorImpl.validateConstraint(ValidatorImpl.java:580) ~[hibernate-validator-5.2.4.Final.jar:5.2.4.Final]
at org.hibernate.validator.internal.engine.ValidatorImpl.validateConstraintsForSingleDefaultGroupElement(ValidatorImpl.java:524) ~[hibernate-validator-5.2.4.Final.jar:5.2.4.Final]
at org.hibernate.validator.internal.engine.ValidatorImpl.validateConstraintsForDefaultGroup(ValidatorImpl.java:492) ~[hibernate-validator-5.2.4.Final.jar:5.2.4.Final]
at org.hibernate.validator.internal.engine.ValidatorImpl.validateConstraintsForCurrentGroup(ValidatorImpl.java:457) ~[hibernate-validator-5.2.4.Final.jar:5.2.4.Final]
at org.hibernate.validator.internal.engine.ValidatorImpl.validateInContext(ValidatorImpl.java:407) ~[hibernate-validator-5.2.4.Final.jar:5.2.4.Final]
at org.hibernate.validator.internal.engine.ValidatorImpl.validate(ValidatorImpl.java:205) ~[hibernate-validator-5.2.4.Final.jar:5.2.4.Final]
at org.hibernate.cfg.beanvalidation.BeanValidationEventListener.validate(BeanValidationEventListener.java:116) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.cfg.beanvalidation.BeanValidationEventListener.onPreInsert(BeanValidationEventListener.java:80) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.action.internal.EntityIdentityInsertAction.preInsert(EntityIdentityInsertAction.java:203) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.action.internal.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:78) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:645) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.engine.spi.ActionQueue.addResolvedEntityInsertAction(ActionQueue.java:282) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.engine.spi.ActionQueue.addInsertAction(ActionQueue.java:263) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.engine.spi.ActionQueue.addAction(ActionQueue.java:317) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.event.internal.AbstractSaveEventListener.addInsertAction(AbstractSaveEventListener.java:330) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:287) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:123) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.event.internal.DefaultMergeEventListener.saveTransientEntity(DefaultMergeEventListener.java:271) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.event.internal.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:243) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:318) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:172) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:70) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:102) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:791) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:778) ~[hibernate-core-5.4.17.Final.jar:5.4.17.Final]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:366) ~[spring-orm-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at com.sun.proxy.$Proxy109.merge(Unknown Source) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:314) ~[spring-orm-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at com.sun.proxy.$Proxy109.merge(Unknown Source) ~[na:na]
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.save(SimpleJpaRepository.java:557) ~[spring-data-jpa-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
at org.springframework.data.repository.core.support.ImplementationInvocationMetadata.invoke(ImplementationInvocationMetadata.java:72) ~[spring-data-commons-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:382) ~[spring-data-commons-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:205) ~[spring-data-commons-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:549) ~[spring-data-commons-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:155) ~[spring-data-commons-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:130) ~[spring-data-commons-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:80) ~[spring-data-commons-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:367) ~[spring-tx-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:118) ~[spring-tx-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:178) ~[spring-data-jpa-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:95) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at com.sun.proxy.$Proxy113.save(Unknown Source) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:205) ~[spring-aop-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at com.sun.proxy.$Proxy81.save(Unknown Source) ~[na:na]
at com.example.schooltimetable.controller.MyController.hello(MyController.java:23) ~[classes/:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.36.jar:9.0.36]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:93) ~[spring-boot-actuator-2.3.1.RELEASE.jar:2.3.1.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) ~[na:na]
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) ~[na:na]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
at java.base/java.lang.Thread.run(Thread.java:834) ~[na:na]

AutoFlush on before query execution and Another query execution attempt on AutoFlush recursion
You try to save your entity and preInsert validation is triggered.
In validation, you are doing a query on the same entity which means before doing the query, hibernate need to flush what is queued in your session.
Trying to flush causes the preInsert validation again and this repeats.
One way to stop Auto flush on query
Unfortunately you have to add a method like this to your repository to stop autoFlush() happening for that query.
#Query("Select count(m) from MyEntity m where m.role = :roleName")
#Transactional(propagation = Propagation.NOT_SUPPORTED)
Long count(String roleName);
When the query is made non transactionally, hibernate doesn't need to flush before the query and so it will not go into recursion.

spring.jpa.properties.javax.persistence.validation.mode=ddl
add this property to your project and i think it will works for you.

java.sql.SQLSyntaxErrorException: Unknown column 'student0_.student_id' in 'field list'

I tried to create a restful API by using spring boot and MySQL in IntelliJ idea. but I got the following error. and I tried to use #Column(name = "last_name") annotation for the Student.java model. but it not succeed. I my MySQL table i used column names by using camel case. but the error shows as Unknown column student_id.
java.sql.SQLSyntaxErrorException: Unknown column 'student0_.student_id' in 'field list'
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:120) ~[mysql-connector-java-8.0.18.jar:8.0.18]
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) ~[mysql-connector-java-8.0.18.jar:8.0.18]
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122) ~[mysql-connector-java-8.0.18.jar:8.0.18]
at com.mysql.cj.jdbc.ClientPreparedStatement.executeInternal(ClientPreparedStatement.java:953) ~[mysql-connector-java-8.0.18.jar:8.0.18]
at com.mysql.cj.jdbc.ClientPreparedStatement.executeQuery(ClientPreparedStatement.java:1003) ~[mysql-connector-java-8.0.18.jar:8.0.18]
at com.zaxxer.hikari.pool.ProxyPreparedStatement.executeQuery(ProxyPreparedStatement.java:52) ~[HikariCP-3.4.1.jar:na]
at com.zaxxer.hikari.pool.HikariProxyPreparedStatement.executeQuery(HikariProxyPreparedStatement.java) ~[HikariCP-3.4.1.jar:na]
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:57) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.loader.Loader.getResultSet(Loader.java:2292) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:2050) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:2012) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.loader.Loader.doQuery(Loader.java:953) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:354) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.loader.Loader.doList(Loader.java:2815) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.loader.Loader.doList(Loader.java:2797) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2629) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.loader.Loader.list(Loader.java:2624) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:506) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:396) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:219) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1396) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.query.internal.AbstractProducedQuery.doList(AbstractProducedQuery.java:1558) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.query.internal.AbstractProducedQuery.list(AbstractProducedQuery.java:1526) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.query.Query.getResultList(Query.java:165) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.hibernate.query.criteria.internal.compile.CriteriaQueryTypeQueryAdapter.getResultList(CriteriaQueryTypeQueryAdapter.java:76) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.findAll(SimpleJpaRepository.java:355) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_202]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_202]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_202]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_202]
at org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:371) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
at org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:204) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:657) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:621) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:605) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:80) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:366) ~[spring-tx-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:99) ~[spring-tx-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:178) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93) ~[spring-aop-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at com.sun.proxy.$Proxy87.findAll(Unknown Source) ~[na:na]
at com.appusers9.controller.StudentController.getAllStudent(StudentController.java:25) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_202]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_202]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_202]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_202]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106) ~[spring-webmvc-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:888) ~[spring-webmvc-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793) ~[spring-webmvc-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.29.jar:9.0.29]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.29.jar:9.0.29]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.29.jar:9.0.29]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.29.jar:9.0.29]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.29.jar:9.0.29]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526) [tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367) [tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860) [tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1591) [tomcat-embed-core-9.0.29.jar:9.0.29]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.29.jar:9.0.29]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_202]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_202]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.29.jar:9.0.29]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_202]
Student.java file.
package com.appusers9.bean;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
#Entity
public class Student {
private int studentId;
private String firstName;
private String lastName;
public Student() {
}
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
public int getStudentId() {
return studentId;
}
public void setStudentId(int studentId) {
this.studentId = studentId;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
}
My application.properties ile be like this.
spring.jpa.hibernate.ddl-auto=none
spring.datasource.url=jdbc:mysql://localhost:3306/tution?user=root&password=19940306
I created a database as tuition and create a table as Student as follows.
So what is the reason for this error?

The exception suggests, the query is looking for column 'student_id' and your table has column with name 'studentId'.
You may either annotate column name in your entity like #Column(name="studentId") or recreate table with changed column name (note same will apply to other columns).
You may get a little more and relevant information here and here

You got this error because you are using camelCase.
private int studentId;
private String firstName;
private String lastName;
Instead you can use:
private int studentid;
private String firstname;
private String lastname;
If you want to make use of different name for your field you can make use of #Column
Note: Changing the field name to #Column(name = "studentId") will give you the same error.

Hibernate findAll(example) throws "java.lang.IllegalArgumentException: Target object must not be null"

I'm currently having the following issue when trying to perform a find all using an Example with a matcher, code:
public List<AlumniProfile> getAllAlumniProfileByExample(AlumniProfile profileToFilterBy) {
ExampleMatcher matcher = ExampleMatcher.matching()
.withIgnoreCase()
.withStringMatcher(ExampleMatcher.StringMatcher.CONTAINING);
Example<AlumniProfile> example = Example.of(profileToFilterBy,matcher);
return alumniProfileDAO.findAll(example);
}
I get the following exception:
java.lang.IllegalArgumentException: Target object must not be null
at org.springframework.util.Assert.notNull(Assert.java:198) ~[spring-core-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.beans.AbstractNestablePropertyAccessor.setWrappedInstance(AbstractNestablePropertyAccessor.java:195) ~[spring-beans-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.beans.BeanWrapperImpl.setWrappedInstance(BeanWrapperImpl.java:153) ~[spring-beans-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.beans.AbstractNestablePropertyAccessor.setWrappedInstance(AbstractNestablePropertyAccessor.java:183) ~[spring-beans-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.beans.AbstractNestablePropertyAccessor.<init>(AbstractNestablePropertyAccessor.java:122) ~[spring-beans-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.beans.BeanWrapperImpl.<init>(BeanWrapperImpl.java:103) ~[spring-beans-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.data.util.DirectFieldAccessFallbackBeanWrapper.<init>(DirectFieldAccessFallbackBeanWrapper.java:36) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.data.jpa.convert.QueryByExamplePredicateBuilder.getPredicates(QueryByExamplePredicateBuilder.java:110) ~[spring-data-jpa-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.data.jpa.convert.QueryByExamplePredicateBuilder.getPredicates(QueryByExamplePredicateBuilder.java:155) ~[spring-data-jpa-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.data.jpa.convert.QueryByExamplePredicateBuilder.getPredicate(QueryByExamplePredicateBuilder.java:89) ~[spring-data-jpa-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.data.jpa.repository.support.SimpleJpaRepository$ExampleSpecification.toPredicate(SimpleJpaRepository.java:812) ~[spring-data-jpa-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.applySpecificationToCriteria(SimpleJpaRepository.java:694) ~[spring-data-jpa-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.getQuery(SimpleJpaRepository.java:625) ~[spring-data-jpa-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.findAll(SimpleJpaRepository.java:439) ~[spring-data-jpa-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_181]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_181]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
at org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:359) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:200) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:644) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:608) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$invoke$3(RepositoryFactorySupport.java:595) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:595) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:59) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:294) ~[spring-tx-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98) ~[spring-tx-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:135) ~[spring-data-jpa-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:61) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at com.sun.proxy.$Proxy136.findAll(Unknown Source) ~[na:na]
at ar.org.pescar.services.AlumniProfileService.getAllAlumniProfileByExample(AlumniProfileService.java:42) ~[classes/:na]
at ar.org.pescar.controller.AlumniController.getAlumniBy(AlumniController.java:136) ~[classes/:na]
at ar.org.pescar.controller.AlumniController$$FastClassBySpringCGLIB$$75bacf1b.invoke(<generated>) ~[classes/:na]
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) ~[spring-core-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:749) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.security.access.intercept.aopalliance.MethodSecurityInterceptor.invoke(MethodSecurityInterceptor.java:69) ~[spring-security-core-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at ar.org.pescar.controller.AlumniController$$EnhancerBySpringCGLIB$$2cea1e92.getAlumniBy(<generated>) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_181]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_181]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:189) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:908) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:660) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:101) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.springframework.boot.actuate.web.trace.servlet.HttpTraceFilter.doFilterInternal(HttpTraceFilter.java:90) ~[spring-boot-actuator-2.1.2.RELEASE.jar:2.1.2.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:320) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:127) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:91) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:119) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:137) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:170) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at ar.org.pescar.security.service.JwtAuthorizationTokenFilter.doFilterInternal(JwtAuthorizationTokenFilter.java:71) ~[classes/:na]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:74) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:215) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:178) ~[spring-security-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:357) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:270) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.filterAndRecordMetrics(WebMvcMetricsFilter.java:117) ~[spring-boot-actuator-2.1.2.RELEASE.jar:2.1.2.RELEASE]
at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:106) ~[spring-boot-actuator-2.1.2.RELEASE.jar:2.1.2.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1417) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.14.jar:9.0.14]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_181]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_181]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.14.jar:9.0.14]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_181]
My entity is:
#Entity
public class AlumniProfile {
#Transient
private static final long serialVersionUID = -8445943548965164378L;
#Id
#Column(name = "ID")
#GeneratedValue(strategy = GenerationType.AUTO, generator = "alumni_seq")
#SequenceGenerator(name = "alumni_seq", sequenceName = "alumni_seq", allocationSize = 1)
private Integer id;
private String telephone;
private String alternativeTelephone;
private String maximumEducation;
private String pescarCenter;
private String counselor;
private Integer graduationYear;
#OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
private Job currentJob;
#OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
private List<Job> jobHistory;
#OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
private Study currentStudy;
#OneToMany(cascade = CascadeType.ALL)
private List<Study> studyHistory;
#OneToOne
#JoinColumn(name="USER_ID", unique=true)
private User user;
public AlumniProfile() {
this.jobHistory = new ArrayList<>();
this.studyHistory = new ArrayList<>();
}
public AlumniProfile(String telephone, String alternativeTelephone,
String maximumEducation, String pescarCenter,
String counselor, Integer graduationYear) {
this.telephone = telephone;
this.alternativeTelephone = alternativeTelephone;
this.maximumEducation = maximumEducation;
this.pescarCenter = pescarCenter;
this.counselor = counselor;
this.graduationYear = graduationYear;
this.jobHistory = new ArrayList<>();
this.studyHistory= new ArrayList<>();
}
public String getTelephone() {
return telephone;
}
public String getAlternativeTelephone() {
return alternativeTelephone;
}
public String getMaximumEducation() {
return maximumEducation;
}
public String getPescarCenter() {
return pescarCenter;
}
public String getCounselor() {
return counselor;
}
public Integer getGraduationYear() {
return graduationYear;
}
public Integer getId() {
return id;
}
public Optional<Job> getCurrentJob() {
return Optional.ofNullable(currentJob);
}
public void setCurrentJob(Job currentJob) {
this.currentJob = currentJob;
}
public void addToJobHistory(Job historyJob) {
this.jobHistory.add(historyJob);
}
public List<Job> getJobHistory() {
return new ArrayList<>(this.jobHistory);
}
public void setCurrentStudy(Study study) {
this.currentStudy = study;
}
public Optional<Study> getCurrentStudy() {
return Optional.ofNullable(currentStudy);
}
public void addToStudyHistory(Study study) {
this.studyHistory.add(study);
}
public List<Study> getStudyHistory() {
return this.studyHistory;
}
//To avoid returning the user object.
#JsonIgnore
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
public void setId(Integer id) {
this.id = id;
}
}
This was previously working when the entity only contained:
#Id
#Column(name = "ID")
#GeneratedValue(strategy = GenerationType.AUTO, generator = "alumni_seq")
#SequenceGenerator(name = "alumni_seq", sequenceName = "alumni_seq", allocationSize = 1)
private Integer id;
private String telephone;
private String alternativeTelephone;
private String maximumEducation;
private String pescarCenter;
private String counselor;
private Integer graduationYear;
But after adding all of the changes I ran the tests and I'm getting this response, I tried executing the post request from Powershell/Postman and from MockMVC in the tests and I get the same result. This is the data that gets loaded to the H2 DB at runtime:
insert into ALUMNI_PROFILE (ID, TELEPHONE, ALTERNATIVE_TELEPHONE, MAXIMUM_EDUCATION, PESCAR_CENTER, COUNSELOR, GRADUATION_YEAR, USER_ID) values (21, 1509276274, 1561494945, 'Universidad', 'Cordoba', 'Calla', 2001, 20);
insert into ALUMNI_PROFILE (ID, TELEPHONE, ALTERNATIVE_TELEPHONE, MAXIMUM_EDUCATION, PESCAR_CENTER, COUNSELOR, GRADUATION_YEAR, USER_ID) values (22, 1500479177, 1524864295, 'Maestria', 'Cordoba', 'Calla', 1993, 21);
insert into ALUMNI_PROFILE (ID, TELEPHONE, ALTERNATIVE_TELEPHONE, MAXIMUM_EDUCATION, PESCAR_CENTER, COUNSELOR, GRADUATION_YEAR, USER_ID) values (23, 1512050663, 1589763064, 'Maestria', 'Lanus', 'Berk', 2000, 22);
Any ideas?

Found the error,
As this entity has relations with other entities and this in the probe are empty it throws the "Target object must not be null", all I needed to add was:
.withIgnorePaths("currentJob","jobHistory","currentStudy","studyHistory","user");
To the ExampleMatcher so it would not check the entities. Now it works like before.
Final code:
ExampleMatcher matcher = ExampleMatcher.matching()
.withIgnoreCase()
.withStringMatcher(ExampleMatcher.StringMatcher.CONTAINING)
.withIgnorePaths("currentJob","jobHistory","currentStudy","studyHistory","user");
Example<AlumniProfile> example = Example.of(profileToFilterBy,matcher);
return alumniProfileDAO.findAll(example);

Hibernate Excpetion More than one row with the given identifier was found

I am coding a blog application and I have a problem with the Hibernate. Problem occurs when I have 2 rows in my User table with the same role_id. After adding a third user with that same id, exception is thrown.
I've tried to set Lazy init. but it doesen't seems to work.
Here is my User class.
#NoArgsConstructor
#Getter
#Setter
#Entity
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String username;
private String password;
private String email;
private String dateCreated;
private String createdBy;
private String dateModified;
private String modifiedBy;
#Transient
private Position position;
#ManyToMany(mappedBy = "users", cascade = CascadeType.ALL)
private Set<Blog> blogs = new HashSet<>();
#OneToMany(mappedBy = "user")
private Set<Post> posts = new HashSet<Post>();
#OneToMany(mappedBy = "user")
private Set<Comment> comments = new HashSet<Comment>();
#OneToOne
#JoinColumn(name = "role_id")
private Role role;
}
Here is my Role class.
#NoArgsConstructor
#Getter
#Setter
#Entity
public class Role {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#Enumerated(EnumType.STRING)
private Position position;
#OneToOne(mappedBy = "role")
private User user;
}
Block of code where excpetion occurs.
#Override
public Set<Role> getAllRoles() {
Iterable<Role> source = roleRepositorium.findAll(); // exception is thrown here
Set<Role> roles = new HashSet<>();
source.forEach(r -> roleToRoleCommand.convert(r));
source.forEach(roles::add);
return roles;
}
Error message.
org.hibernate.HibernateException: More than one row with the given identifier was found: 1, for class: com.app.blog.models.User
at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:90) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.loader.entity.EntityLoader.loadByUniqueKey(EntityLoader.java:144) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.persister.entity.AbstractEntityPersister.loadByUniqueKey(AbstractEntityPersister.java:2351) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.type.EntityType.loadByUniqueKey(EntityType.java:739) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.type.EntityType.resolve(EntityType.java:467) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.engine.internal.TwoPhaseLoad.doInitializeEntity(TwoPhaseLoad.java:172) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.engine.internal.TwoPhaseLoad.initializeEntity(TwoPhaseLoad.java:129) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.loader.Loader.initializeEntitiesAndCollections(Loader.java:1151) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.loader.Loader.processResultSet(Loader.java:1010) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.loader.Loader.doQuery(Loader.java:948) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:340) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.loader.Loader.doList(Loader.java:2689) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.loader.Loader.doList(Loader.java:2672) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2506) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.loader.Loader.list(Loader.java:2501) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:504) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:395) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:220) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1508) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.query.internal.AbstractProducedQuery.doList(AbstractProducedQuery.java:1537) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.query.internal.AbstractProducedQuery.list(AbstractProducedQuery.java:1505) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.query.Query.getResultList(Query.java:135) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.query.criteria.internal.compile.CriteriaQueryTypeQueryAdapter.getResultList(CriteriaQueryTypeQueryAdapter.java:74) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.findAll(SimpleJpaRepository.java:306) ~[spring-data-jpa-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.findAll(SimpleJpaRepository.java:73) ~[spring-data-jpa-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_191]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_191]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_191]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_191]
at org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:359) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:200) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:644) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:608) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$invoke$3(RepositoryFactorySupport.java:595) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:595) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:59) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:294) ~[spring-tx-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98) ~[spring-tx-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:135) ~[spring-data-jpa-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:61) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at com.sun.proxy.$Proxy114.findAll(Unknown Source) ~[na:na]
at com.app.blog.services.RoleService.getAllRoles(RoleService.java:23) ~[classes/:na]
at com.app.blog.controllers.UserController.showRegisterPage(UserController.java:36) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_191]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_191]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_191]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_191]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:189) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882) ~[spring-webmvc-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.springframework.boot.actuate.web.trace.servlet.HttpTraceFilter.doFilterInternal(HttpTraceFilter.java:90) ~[spring-boot-actuator-2.1.2.RELEASE.jar:2.1.2.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:92) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.filterAndRecordMetrics(WebMvcMetricsFilter.java:117) ~[spring-boot-actuator-2.1.2.RELEASE.jar:2.1.2.RELEASE]
at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:106) ~[spring-boot-actuator-2.1.2.RELEASE.jar:2.1.2.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.4.RELEASE.jar:5.1.4.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) ~[tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1417) [tomcat-embed-core-9.0.14.jar:9.0.14]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.14.jar:9.0.14]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_191]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_191]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.14.jar:9.0.14]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_191]

You should use #ManyToOne and #OneToMany annotations instead if an user has a single role but one role can belong to one or more users
Check this tutorial:
https://www.baeldung.com/hibernate-one-to-many
Also, here are some useful thoughts on thinkins these relations between entities:
https://thoughts-on-java.org/best-practices-many-one-one-many-associations-mappings/

The problem is that you have mapped Role and User as one to one when in reality there can be many users who have the same role and in fact, contrary to the above answer, usually many roles that a single user can have.
In your case Role is mapped one to one to User so when hibernate loads that entity from the DB, it sees that there are more than 1 result associated with it and finds an exception. That's the exception you're seeing.
You actually want to be using #ManyToMany if a User can have multiple Roles and of course the same Role can belong to many users.

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column 'city0_.country_code' in 'field list' with SpringBoot

Trying to create a simple SpringBoot application - Api with DataBase, using Gradle. When trying to get data from the Table, using api call, getting an exception in a Postman:
{
"timestamp": "2018-04-01T12:45:40.218+0000",
"status": 500,
"error": "Internal Server Error",
"message": "could not extract ResultSet; SQL [n/a]; nested exception is org.hibernate.exception.SQLGrammarException: could not extract ResultSet",
"path": "/api/demo/towns"
}
In the Idea having next exception:
2018-04-01 15:44:29.553 ERROR 17532 --- [nio-8080-exec-2]
o.h.engine.jdbc.spi.SqlExceptionHelper : Unknown column
'city0_.country_code' in 'field list' 2018-04-01 15:44:29.578 ERROR
17532 --- [nio-8080-exec-2] o.a.c.c.C.[.[.[/].[dispatcherServlet] :
Servlet.service() for servlet [dispatcherServlet] in context with path
[] threw exception [Request processing failed; nested exception is
org.springframework.dao.InvalidDataAccessResourceUsageException: could
not extract ResultSet; SQL [n/a]; nested exception is
org.hibernate.exception.SQLGrammarException: could not extract
ResultSet] with root cause
com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown
column 'city0_.country_code' in 'field list' at
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
~[na:1.8.0_144] at
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
~[na:1.8.0_144] at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
~[na:1.8.0_144] at
java.lang.reflect.Constructor.newInstance(Constructor.java:423)
~[na:1.8.0_144] at
com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
~[mysql-connector-java-5.1.45.jar:5.1.45] at
com.mysql.jdbc.Util.getInstance(Util.java:408)
~[mysql-connector-java-5.1.45.jar:5.1.45] at
com.mysql.jdbc.SQLError.createSQLException(SQLError.java:944)
~[mysql-connector-java-5.1.45.jar:5.1.45] at
com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3973)
~[mysql-connector-java-5.1.45.jar:5.1.45] at
com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3909)
~[mysql-connector-java-5.1.45.jar:5.1.45] at
com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2527)
~[mysql-connector-java-5.1.45.jar:5.1.45] at
com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2680)
~[mysql-connector-java-5.1.45.jar:5.1.45] at
com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2484)
~[mysql-connector-java-5.1.45.jar:5.1.45] at
com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1858)
~[mysql-connector-java-5.1.45.jar:5.1.45] at
com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1966)
~[mysql-connector-java-5.1.45.jar:5.1.45] at
com.zaxxer.hikari.pool.ProxyPreparedStatement.executeQuery(ProxyPreparedStatement.java:52)
~[HikariCP-2.7.8.jar:na] at
com.zaxxer.hikari.pool.HikariProxyPreparedStatement.executeQuery(HikariProxyPreparedStatement.java)
~[HikariCP-2.7.8.jar:na] at
org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:60)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.loader.Loader.getResultSet(Loader.java:2168)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1931)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1893)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.loader.Loader.doQuery(Loader.java:938)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:341)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.loader.Loader.doList(Loader.java:2692)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.loader.Loader.doList(Loader.java:2675)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2507)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.loader.Loader.list(Loader.java:2502)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:502)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:392)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:216)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.internal.SessionImpl.list(SessionImpl.java:1489)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.query.internal.AbstractProducedQuery.doList(AbstractProducedQuery.java:1445)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.query.internal.AbstractProducedQuery.list(AbstractProducedQuery.java:1414)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.query.Query.getResultList(Query.java:146)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.hibernate.query.criteria.internal.compile.CriteriaQueryTypeQueryAdapter.getResultList(CriteriaQueryTypeQueryAdapter.java:72)
~[hibernate-core-5.2.14.Final.jar:5.2.14.Final] at
org.springframework.data.jpa.repository.support.SimpleJpaRepository.findAll(SimpleJpaRepository.java:307)
~[spring-data-jpa-2.0.5.RELEASE.jar:2.0.5.RELEASE] at
org.springframework.data.jpa.repository.support.SimpleJpaRepository.findAll(SimpleJpaRepository.java:74)
~[spring-data-jpa-2.0.5.RELEASE.jar:2.0.5.RELEASE] at
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
~[na:1.8.0_144] at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
~[na:1.8.0_144] at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
~[na:1.8.0_144] at java.lang.reflect.Method.invoke(Method.java:498)
~[na:1.8.0_144] at
org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:377)
~[spring-data-commons-2.0.5.RELEASE.jar:2.0.5.RELEASE] at
org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:200)
~[spring-data-commons-2.0.5.RELEASE.jar:2.0.5.RELEASE] at
org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:629)
~[spring-data-commons-2.0.5.RELEASE.jar:2.0.5.RELEASE] at
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
~[spring-aop-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:593)
~[spring-data-commons-2.0.5.RELEASE.jar:2.0.5.RELEASE] at
org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:578)
~[spring-data-commons-2.0.5.RELEASE.jar:2.0.5.RELEASE] at
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
~[spring-aop-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:59)
~[spring-data-commons-2.0.5.RELEASE.jar:2.0.5.RELEASE] at
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
~[spring-aop-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:294)
~[spring-tx-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98)
~[spring-tx-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
~[spring-aop-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139)
~[spring-tx-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
~[spring-aop-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:135)
~[spring-data-jpa-2.0.5.RELEASE.jar:2.0.5.RELEASE] at
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
~[spring-aop-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
~[spring-aop-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
~[spring-aop-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:61)
~[spring-data-commons-2.0.5.RELEASE.jar:2.0.5.RELEASE] at
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
~[spring-aop-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212)
~[spring-aop-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
com.sun.proxy.$Proxy82.findAll(Unknown Source) ~[na:na] at
com.apidbdemo.controllers.DemoController.getTowns(DemoController.java:27)
~[classes/:na] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native
Method) ~[na:1.8.0_144] at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
~[na:1.8.0_144] at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
~[na:1.8.0_144] at java.lang.reflect.Method.invoke(Method.java:498)
~[na:1.8.0_144] at
org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209)
~[spring-web-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
~[spring-web-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
~[spring-webmvc-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:870)
~[spring-webmvc-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:776)
~[spring-webmvc-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
~[spring-webmvc-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991)
~[spring-webmvc-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
~[spring-webmvc-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:978)
~[spring-webmvc-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:870)
~[spring-webmvc-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
~[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:855)
~[spring-webmvc-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
~[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
~[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
~[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
~[tomcat-embed-websocket-8.5.28.jar:8.5.28] at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
~[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
~[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)
~[spring-web-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
~[spring-web-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
~[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
~[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109)
~[spring-web-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
~[spring-web-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
~[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
~[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81)
~[spring-web-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
~[spring-web-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
~[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
~[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200)
~[spring-web-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
~[spring-web-5.0.4.RELEASE.jar:5.0.4.RELEASE] at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
~[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
~[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
~[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:496)
[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803)
[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790)
[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459)
[tomcat-embed-core-8.5.28.jar:8.5.28] at
org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
[tomcat-embed-core-8.5.28.jar:8.5.28] at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
[na:1.8.0_144] at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
[na:1.8.0_144] at
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
[tomcat-embed-core-8.5.28.jar:8.5.28] at
java.lang.Thread.run(Thread.java:748) [na:1.8.0_144]
I see that problem is with the CountryCode column, but don't understand, what is with it.
Using MySql DB, one table. It's structure:
Main entity:
#Entity
#Table(name="city")
public class City implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
#Column(name="Name")
private String name;
#Column(name="CountryCode")
private String countryCode;
#Column(name="District")
private String district;
#Column(name="Population")
private int population;
public int getId(){
return id;
}
public void setId(int id){
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getCountryCode() {
return countryCode;
}
public void setCountryCode(String countryCode) {
this.countryCode = countryCode;
}
public String getDistrict() {
return district;
}
public void setDistrict(String district) {
this.district = district;
}
public int getPopulation() {
return population;
}
public void setPopulation(int population) {
this.population = population;
}
public City(String name, String countryCode, String district, int population){
this.name = name;
this.countryCode = countryCode;
this.district = district;
this.population = population;
}
public City(){
}
}
Repository:
#Repository("cityRepository")
public interface CityRepository extends CrudRepository<City, Integer> {
}
Controller:
#RestController
#RequestMapping("/api/demo")
public class DemoController {
#Autowired
#Qualifier("cityRepository")
private CityRepository cityRepository;
#RequestMapping(value = "towns",
method = RequestMethod.GET,
produces = {MimeTypeUtils.APPLICATION_JSON_VALUE},
headers = "Accept=application/json")
public ResponseEntity<Iterable<City>> getTowns() {
Iterable<City> list = cityRepository.findAll();
return new ResponseEntity<Iterable<City>>(list, HttpStatus.OK);
}
}

Thanks to #JB Nizet answer, after I added property: spring.jpa.hibernate.naming.physical-strategy=org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl into application.property file, all is working. Thanks.