如何使用“构造函数”在“选择子句”中为多个表的选定列编写HQL JOIN查询
我正在使用Constructor() 在Select子句中为多个表的选定列编写HQL JOIN查询
我有以下实体 ：
实体1：NotificationObject.java
@Entity @Table(name="notification_object") public class NotificationObject implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue( strategy=GenerationType.IDENTITY ) @Column( columnDefinition="INT(10) UNSIGNED" ) private Integer id; @Column( name="entity_type_id", columnDefinition="TINYINT UNSIGNED", nullable=false ) private Short entityTypeId; @Column( name="entity_id", columnDefinition="INT(10) UNSIGNED", nullable=false ) private Integer entityId; @DateTimeFormat( pattern="yyyy-MM-dd" ) @Temporal( TemporalType.TIMESTAMP ) @CreationTimestamp @Column( name="created_on"/*, nullable=false*/ ) private Date createdOn; @OneToMany( mappedBy = "notificationObject" ) private Set notifications = new LinkedHashSet(); public NotificationObject() {} public NotificationObject(Short entityTypeId, Integer entityId) { this.entityTypeId = entityTypeId; this.entityId = entityId; } // Getters and Setters }
实体2：NotificationChange.java
@Entity @Table(name="notification_change") public class NotificationChange implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy=GenerationType.IDENTITY) @Column(columnDefinition="INT(10) UNSIGNED") private Integer id; @ManyToOne( fetch=FetchType.LAZY ) @JoinColumn( name="notification_object_id", nullable=false, foreignKey=@ForeignKey(name="fk_notification_change_notification_object_noti_object_id") ) private NotificationObject notificationObject; @ManyToOne(fetch=FetchType.LAZY) @JoinColumn( name="actor_id", columnDefinition="INT(10) UNSIGNED", nullable=false, foreignKey=@ForeignKey(name="fk_notification_change_user_user_id") ) private User actor; public NotificationChange() {} public NotificationChange( User actor ) { this.actor = actor; } // Getters and Setters }
实体3：Notification.java
@Entity @Table(name="notification") public class Notification implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue( strategy=GenerationType.IDENTITY ) @Column( columnDefinition="INT(10) UNSIGNED" ) private Integer id; @ManyToOne( fetch=FetchType.LAZY ) @JoinColumn( name="notification_object_id", nullable=false, foreignKey=@ForeignKey(name="fk_notification_notification_object_notification_object_id") ) private NotificationObject notificationObject; @ManyToOne( fetch=FetchType.LAZY ) @JoinColumn( name="notifier_id", columnDefinition="INT(10) UNSIGNED", nullable=false, foreignKey=@ForeignKey(name="fk_notification_user_user_id") ) private User notifier; @Column( name="is_seen", nullable=false ) private boolean isSeen; @Column( name="is_viewed", nullable=false ) private boolean isViewed; public Notification() {} public Notification( User notifier, boolean isSeen, boolean isViewed ) { this.notifier = notifier; this.isSeen = isSeen; this.isViewed = isViewed; } // Getters and Setters }
实体4：User.java
@Entity @Table(name="user") public class User implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy=GenerationType.IDENTITY) @Column(name="user_id") private String user_id; // Extra fields @OneToOne(cascade=CascadeType.MERGE) @JoinColumn(name="emp_id", columnDefinition="INT(10) UNSIGNED") private Employee employee; @OneToMany( mappedBy="notifier" ) private Set notifications = new LinkedHashSet(); public User() {} public User(String user_id) { this.user_id = user_id; } // Getters and Setters }
实体5：Employee.java
@Entity @Table(name="employee") public class Employee implements Serializable { private static final long serialVersionUID = 1L; public Employee() { } public Employee( String emp_id ) { this.emp_id = emp_id; } @Id @GeneratedValue(strategy=GenerationType.IDENTITY) @Column(name="emp_id") private String emp_id; @Column(name="first_name") private String first_name; @Column(name="last_name") private String last_name; // Extra fields @OneToOne(mappedBy="employee") @JsonBackReference private User user; // Getters and Setters }
DTO 1：Notify.java
public class Notify { private Integer notificationObjectId, notificationId, notifierId, actorId, entityId; private Short entityTypeId; private String notifierName, actorName, message, notificationLink; private Date createdOn; private boolean isSeen, isViewed; public Notify() {} public Notify ( Integer notificationObjectId, Integer notificationId, Integer notifierId, Integer actorId, Integer entityId, Short entityTypeId, String notifierName, String actorName, String message, String notificationLink, Date createdOn, boolean isSeen, boolean isViewed ) { // Set Values Here } public Notify (Integer notificationObjectId, Integer notificationId, Integer notifierId, String notifierName, Integer actorId, String actorName, Integer entityId, Short entityTypeId, Date createdOn, boolean isSeen, boolean isViewed ) { // Or Here } // Getters and Setters }
我在JOINs很弱。
我想为实体的选定字段编写HQL JOIN查询以形成Constructor() 在 Notify.java DTO 的Select子句中。
我试过的：
查询1
final String GET_NOTIFICATIONS_FOR_USER = "select new support.dto.Notify ( no.id, n.id, Integer.parseInt( n.notifier.user_id ), " + "concat ( n.notifier.employee.first_name, ' ', n.notifier.employee.last_name ), " + "Integer.parseInt( nc.actor.user_id ), concat( nc.actor.employee.first_name, ' ', nc.actor.employee.last_name ), " + "no.entityId, no.entityTypeId, no.createdOn, n.isSeen, n.isViewed ) " + "from Notification n, NotificationObject no, NotificationChange nc, User u, Employee e " + "where n.notifier.user_id = :notifierId";
查询2
final String GET_NOTIFICATIONS_FOR_USER = "select new support.dto.Notify ( no.id, n.id, Integer.parseInt( n.notifier.user_id ), " + "concat ( n.notifier.employee.first_name, ' ', n.notifier.employee.first_name ), " + "Integer.parseInt( nc.actor.user_id ), concat( nc.actor.employee.first_name, ' ', nc.actor.employee.last_name ), " + "no.entityId, no.entityTypeId, no.createdOn, n.isSeen, n.isViewed ) " + "from NotificationChange nc inner join nc.notificationObject no " + "inner join no.notifications n " + "where n.notifier.user_id = :notifierId";
我正在接受以下exception
org.hibernate.internal.util.ReflectHelper.getConstructor（ReflectHelper.java：309）中的org.hibernate.hql.internal.ast.tree.ConstructorNode.resolveConstructor（ConstructorNode.java:174）中的java.lang.NullPointerException。 hibernate.hql.internal.ast.tree.ConstructorNode.prepare（ConstructorNode.java:144）位于org.hibernate.hql.internal的org.hibernate.hql.internal.ast.HqlSqlWalker.processConstructor（HqlSqlWalker.java:1091）。 antlr.HqlSqlBaseWalker.selectExpr（HqlSqlBaseWalker.java:2328）org.hibernate.hql.internal.antlr.HqlSqlWalker.selectExprList（HqlSqlBaseWalker.java:2194）org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectClause（HqlSqlBaseWalker。 java：1476）org.hibernate上的org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query（HqlSqlBaseWalker.java:573）org.hibernate.hql.internal.antlr.HqlSqlWalker.selectStatement（HqlSqlBaseWalker.java:301） org.hibernate.hql.internal.ast.QueryTranslatorImp中的.hql.internal.antlr.HqlSqlBaseWalker.statement（HqlSqlBaseWalker.java:249） l.analyze（QueryTranslatorImpl.java:262）org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile（QueryTranslatorImpl.java:190）org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile（QueryTranslatorImpl.java： 142）atg.hibernate.engine.query.spi.HQLQueryPlan。（HQLQueryPlan.java:115）位于org.hibernate.engine.query的org.hibernate.engine.query.spi.HQLQueryPlan。（HQLQueryPlan.java:76）。 org.hibernate.internal.AbstractSessionImpl.getHQLQueryPlan（AbstractSessionImpl.java:298）中的org.hibernate.internal.AbstractSessionImpl.createQuery（AbstractSessionImpl.java:236）中的.spi.QueryPlanCache.getHQLQueryPlan（QueryPlanCache.java:150）。位于support.service.MasterServiceImpl的support.service.MasterServiceImpl.getNotifications（MasterServiceImpl.java:158）的support.DAO.MasterDaoImpl.getNotifications（MasterDaoImpl.java:115）上的hibernate.internal.SessionImpl.createQuery（SessionImpl.java:1821） $$ FastClassBySpringCGLIB $$ a355463b.invoke（）at org.springframework.cglib.proxy.MethodProxy.invoke（Meth odProxy.java:204）org.springframework上的org.springframework.aop.frame.CglibAopProxy $ CglibMethodInvocation.invokeJoinpoint（CglibAopProxy.java:717）org.springframework.aop.framework.ReflectiveMethodInvocation.proceed（ReflectiveMethodInvocation.java:157） org.springframework.aop.framework.CglibAopProxy $ DynamicAdvisedInterceptor.intercept（CglibAopProxy）中org.springframework.aop.framework.ReflectiveMethodInvocation.proceed（ReflectiveMethodInvocation.java:179）中的.aop.interceptor.ExposeInvocationInterceptor.invoke（ExposeInvocationInterceptor.java:92） .java：653）atsupport.service.MasterServiceImpl $$ EnhancerBySpringCGLIB $$ 8c2728e2.getNotifications（）at sun.reflect.NativeMethodAccessorImpl.invoke0（Native Method）at the support.controller.WebSocketController.hello（WebSocketController.java:91） .reflect.NativeMethodAccessorImpl.invoke（NativeMethodAccessorImpl.java:57）at sun.reflect.DelegatingMethodAccessorImpl.invoke（DelegatingMethodAccessorImpl.java:43）at java.lang.reflect.Method.in vg（Method.java:601）org.springframework.messaging.handler.invocation.InvocableHandlerMethod.doInvoke（InvocableHandlerMethod.java:185）org.springframework.messaging.handler.invocation.InvocableHandlerMethod.invoke（InvocableHandlerMethod.java:104） org.springframework.messaging.handler.invocation.AbstractMethodMessageHandler.handleMatch（AbstractMethodMessageHandler.java:447）atg.springframework.messaging.simp.annotation.support.SimpAnnotationMethodMessageHandler.handleMatch（SimpAnnotationMethodMessageHandler.java:443）org.springframework.messaging org.springframework.messaging.handler.invocation.AbstractMethodMessageHandler上的org.springframework.messaging.handler.invocation.AbstractMethodMessageHandler.handleMessageInternal（AbstractMethodMessageHandler.java:408）中的.simp.annotation.support.SimpAnnotationMethodMessageHandler.handleMatch（SimpAnnotationMethodMessageHandler.java:82） org.springframework.messaging.support中的.handleMessage（AbstractMethodMessageHandler.java:346）。 ExecutorSubscribableChannel $ SendTask.run（ExecutorSubscribableChannel.java:135）at java.util.concurrent.ThreadPoolExecutor.runWorker（ThreadPoolExecutor.java:1110）at java.util.concurrent.ThreadPoolExecutor $ Worker.run（ThreadPoolExecutor.java:603）at java .lang.Thread.run（Thread.java:722）
该错误告诉您Hibernate无法找到Notify构造函数。
此外，您不能在HQL查询中添加Integer.parseInt 。 使用ResultSet中的预期类型，并从传入参数在构造函数内部执行转换。