如何在 Spring 引导中使用 JPA 从数据库中获取特定列（尝试从数据库中获取特定列时出现异常）？

Question

我有一个表和另一个与 oneToMany 关系连接的子表。 我想在辅助表的基础上从主表和辅助表中获取数据，不包括主表中的其他字段。 我正在尝试使用带有构造函数的 JPA 查询来获取数据，以在 Bean 中设置字段并在控制台中获取异常。

1.实体表：

@Entity
@Getter @Setter
@Accessors(chain = true)
@NoArgsConstructor
@JsonIgnoreProperties(ignoreUnknown = true)
@Table(name="entity")
@JsonInclude(value = Include.NON_NULL)
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property="entityId")
public class EntityModel implements Serializable {

    private static final long serialVersionUID = 8087473285130713445L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer entityId;
    
    @Column(length = 100, nullable = false)
    private String legalName;
    //other fields
    //.....
    //....
    @OneToMany(fetch=FetchType.LAZY,mappedBy = "entity")
    private Set<EntityRoles> entityRoles;
    
    public EntityModel(Integer entityId,String legalName,Set<EntityRoles> entityRoles){
        this.entityId = entityId;
        this.legalName = legalName;
        this.entityRoles = entityRoles;
    }
}

2.Entity角色表：

@Getter @Setter
@Accessors(chain = true)
@Entity
@NoArgsConstructor
@AllArgsConstructor
@Table(name = "entity_roles")
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property="entityRolesId")
public class EntityRoles implements Serializable {

    private static final long serialVersionUID = 4335089064220416028L;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer entityRolesId;
    
    @Column(length = 10, nullable = false)
    private String roleName;
    
    @ManyToOne
    @JoinColumn(name = "entity_id", nullable = false)
    private EntityModel entity;

    public EntityRoles(Integer entityRolesId, String roleName) {
        super();
        this.entityRolesId = entityRolesId;
        this.roleName = roleName;
    }
    
}

3.存储库：

@Repository
public interface EntityRepo extends JpaRepository<EntityModel, Integer>{

@Query(value = "SELECT new EntityModel(e.entityId,e.legalName,e.entityRoles) FROM EntityModel AS e INNER JOIN e.entityRoles er WHERE er.roleName NOT IN('FINANCIER','HOST','BUYER')")
    Page<EntityModel> findAllByAnchorSellerAndDealerEntity(Pageable page);
}

异常（堆栈跟踪）：

org.springframework.dao.InvalidDataAccessResourceUsageException: could not extract ResultSet; SQL [n/a]; nested exception is org.hibernate.exception.SQLGrammarException: could not extract ResultSet
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.convertHibernateAccessException(HibernateJpaDialect.java:281)
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:255)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:528)
    at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:61)
    at org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:242)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:153)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:149)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212)
    at com.sun.proxy.$Proxy153.findAllByAnchorSellerAndDealerEntity(Unknown Source)
    at com.entpaynet.service.EntityService.getEntityByTypeWithPage(EntityService.java:253)
    at com.entpaynet.service.EntityService$$FastClassBySpringCGLIB$$879e027e.invoke(<generated>)
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:685)
    at com.entpaynet.service.EntityService$$EnhancerBySpringCGLIB$$ad961a7f.getEntityByTypeWithPage(<generated>)
    at com.entpaynet.controller.EntityController.getEntityByPage(EntityController.java:215)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:567)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:888)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:108)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1591)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.base/java.lang.Thread.run(Thread.java:835)
Caused by: org.hibernate.exception.SQLGrammarException: could not extract ResultSet
    at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:63)
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:42)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:113)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:99)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:67)
    at org.hibernate.loader.Loader.getResultSet(Loader.java:2292)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:2050)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:2012)
    at org.hibernate.loader.Loader.doQuery(Loader.java:953)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:354)
    at org.hibernate.loader.Loader.doList(Loader.java:2815)
    at org.hibernate.loader.Loader.doList(Loader.java:2797)
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2629)
    at org.hibernate.loader.Loader.list(Loader.java:2624)
    at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:506)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:396)
    at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:219)
    at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1396)
    at org.hibernate.query.internal.AbstractProducedQuery.doList(AbstractProducedQuery.java:1558)
    at org.hibernate.query.internal.AbstractProducedQuery.list(AbstractProducedQuery.java:1526)
    at org.hibernate.query.Query.getResultList(Query.java:165)
    at org.springframework.data.jpa.repository.query.JpaQueryExecution$PagedExecution.doExecute(JpaQueryExecution.java:177)
    at org.springframework.data.jpa.repository.query.JpaQueryExecution.execute(JpaQueryExecution.java:88)
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.doExecute(AbstractJpaQuery.java:154)
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.execute(AbstractJpaQuery.java:142)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:618)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:605)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:80)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:366)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:99)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139)
    ... 67 common frames omitted
Caused by: java.sql.SQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '. as col_14_0_ from entity entitymode0_ inner join entity_roles entityrole1_ on ' at line 1
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:120)
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
    at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
    at com.mysql.cj.jdbc.ClientPreparedStatement.executeInternal(ClientPreparedStatement.java:953)
    at com.mysql.cj.jdbc.ClientPreparedStatement.executeQuery(ClientPreparedStatement.java:1003)
    at com.zaxxer.hikari.pool.ProxyPreparedStatement.executeQuery(ProxyPreparedStatement.java:52)
    at com.zaxxer.hikari.pool.HikariProxyPreparedStatement.executeQuery(HikariProxyPreparedStatement.java)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:57)
    ... 96 common frames omitted

由于以下列导致异常：

@OneToMany(fetch=FetchType.LAZY,mappedBy = "entity")
private Set<EntityRoles> entityRoles;

在这种情况下如何获取数据？

Answer 1

您正在使用 new 运算符。 这是为了创建不查询实体的 DTO。 您的查询应如下所示：

@Query("SELECT e FROM EntityModel e INNER JOIN e.entityRoles er " + 
       "WHERE er.roleName NOT IN('FINANCIER','HOST','BUYER')")
Page<EntityModel> findAllByAnchorSellerAndDealerEntity(Pageable page);
}

或者，如果您想要一个 DTO，则必须创建一个必须与完全限定的类名一起使用的 DTO

@Query("SELECT NEW packagename.EntityDTO(e.entityId,e.legalName,e.entityRoles) "+
       "FROM EntityModel e INNER JOIN e.entityRoles er " + 
       "WHERE er.roleName NOT IN('FINANCIER','HOST','BUYER')")
Page<EntityDTO> findAllByAnchorSellerAndDealerEntity(Pageable page);
}