我正在尝试使用连接制作一个非常简单的 JPQL，但我的成功率为零。给定用户 ID，我想获取用户的最近登录日期。我正在使用 Spring Data JPA + Hibernate。
我有一个 MySQL 数据库，其中包含表 Activity：
@Table(name = "activity")
@SuppressWarnings("serial")
public class Activity implements Serializable {
@Id
@GeneratedValue
private Long id;
@Column(name = "date", insertable = true, nullable = false, updatable = false)
@Temporal(TemporalType.TIMESTAMP)
private Date date;
@Column(insertable = true, name = "organization_id", nullable = true, updatable = true, unique = false)
@Basic(optional = true)
private Long organizationId;
@Column(insertable = true, name = "operation", nullable = false, updatable = true, unique = false)
@Basic(optional = false)
private String operation;
//getters and setters
}
它包含许多其他表，包括 LoginAttempt：
@Table(name = "login_attempt")
@SuppressWarnings("serial")
public class LoginAttempt implements Serializable{
@Id
@GeneratedValue
private Long id;
@OneToOne(fetch = FetchType.EAGER, optional = false)
@Basic(optional = false)
@JoinColumn(name = "activity_id", insertable = true, nullable = false, unique = false, updatable = false)
private Activity activity;
@Column(insertable = true, name = "user_id", nullable = true, updatable = true, unique = false)
@Basic(optional = true)
private Long userId;
@Column(insertable = true, name = "user_email", nullable = true, updatable = true, unique = false)
@Basic(optional = true)
private String userEmail;
@Column(insertable = true, name = "login_successful", nullable = false, updatable = true, unique = false)
@Basic(optional = false)
private boolean loginSuccessful;
//getters and setters
}
所有其他表都使用名为“activity_id”的列引用 Activity。
这是我的 DAO，带有一种方法和 @Query 注释。
public interface MyDAO extends JpaRepository<Activity, Long> {
@Query("SELECT a FROM Activity a, LoginAttempt la JOIN a.id la WHERE la.user_email = (:userId) AND a.date = (SELECT MAX(a.date))")
public Activity findMostRecentLoginForUser(@Param("userId") Long userId);
}
当我在 @Query 中有一个简单的全选语句时，它可以工作，所以我正确连接到数据库并且能够取回所有内容。起初我在查询中遇到了很多验证错误，但现在我得到了以下信息（部分堆栈跟踪）。
Caused by: java.lang.IllegalArgumentException: Validation failed for query for method public abstract com.domain.Activity com.dao.MyDAO.findMostRecentLoginForUser(java.lang.Long)!
at org.springframework.data.jpa.repository.query.SimpleJpaQuery.validateQuery(SimpleJpaQuery.java:97)
at org.springframework.data.jpa.repository.query.SimpleJpaQuery.<init>(SimpleJpaQuery.java:66)
at org.springframework.data.jpa.repository.query.SimpleJpaQuery.fromQueryAnnotation(SimpleJpaQuery.java:169)
at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$DeclaredQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:114)
at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$CreateIfNotFoundQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:160)
at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$AbstractQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:68)
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.<init>(RepositoryFactorySupport.java:290)
at org.springframework.data.repository.core.support.RepositoryFactorySupport.getRepository(RepositoryFactorySupport.java:158)
at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.getObject(RepositoryFactoryBeanSupport.java:162)
at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.getObject(RepositoryFactoryBeanSupport.java:44)
at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:142)
... 44 more
Caused by: java.lang.NullPointerException
at org.hibernate.hql.internal.ast.HqlSqlWalker.createFromJoinElement(HqlSqlWalker.java:393)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.joinElement(HqlSqlBaseWalker.java:3645)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElement(HqlSqlBaseWalker.java:3431)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElementList(HqlSqlBaseWalker.java:3309)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromClause(HqlSqlBaseWalker.java:706)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:562)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:299)
at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:247)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:250)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:185)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:138)
at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:105)
at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:80)
at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:168)
at org.hibernate.internal.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:221)
at org.hibernate.internal.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:199)
at org.hibernate.internal.SessionImpl.createQuery(SessionImpl.java:1778)
at org.hibernate.ejb.AbstractEntityManagerImpl.createQuery(AbstractEntityManagerImpl.java:291)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:366)
at com.sun.proxy.$Proxy33.createQuery(Unknown Source)
at org.springframework.data.jpa.repository.query.SimpleJpaQuery.validateQuery(SimpleJpaQuery.java:91)
... 54 more
我的大脑被炸了，我无法理解我读过的任何例子。任何帮助表示赞赏。谢谢。