查询方法public abstract java.util.List的validation失败
我有一个基本的SpringBoot应用程序。 使用Spring Initializer，JPA，嵌入式Tomcat，Thymeleaf模板引擎和包作为可执行的JAR文件。 SpringBoot的版本是2.0.1.RELEASE。 我已经创建了一个使用此方法从CrudRepository扩展的类存储库
@Query("select us.priceAlertsTapas.tapa from User us left join us.priceAlertsTapas pat left join pat.tapa tapa where pat.priceAlert = ?1") List tapasByUserPriceAlert (PriceAlert pa); 但是当我启动项目时，我收到了这个错误：
Validation failed for query for method public abstract java.util.List at org.springframework.data.jpa.repository.query.SimpleJpaQuery.validateQuery(SimpleJpaQuery.java:93) at org.springframework.data.jpa.repository.query.SimpleJpaQuery.(SimpleJpaQuery.java:63) at org.springframework.data.jpa.repository.query.JpaQueryFactory.fromMethodWithQueryString(JpaQueryFactory.java:76) at org.springframework.data.jpa.repository.query.JpaQueryFactory.fromQueryAnnotation(JpaQueryFactory.java:56) at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$DeclaredQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:139) at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$CreateIfNotFoundQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:206) at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$AbstractQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:79) at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lookupQuery(RepositoryFactorySupport.java:553) at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$mapMethodsToQuery$1(RepositoryFactorySupport.java:546) at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193) at java.util.Iterator.forEachRemaining(Iterator.java:116) at java.util.Collections$UnmodifiableCollection$1.forEachRemaining(Collections.java:1049) at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801) at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481) at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471) at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708) at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499) at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.mapMethodsToQuery(RepositoryFactorySupport.java:548) at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$new$0(RepositoryFactorySupport.java:538) at java.util.Optional.map(Optional.java:215) at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.(RepositoryFactorySupport.java:538) at org.springframework.data.repository.core.support.RepositoryFactorySupport.getRepository(RepositoryFactorySupport.java:317) at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.lambda$afterPropertiesSet$3(RepositoryFactoryBeanSupport.java:287) at org.springframework.data.util.Lazy.getNullable(Lazy.java:141) at org.springframework.data.util.Lazy.get(Lazy.java:63) at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.afterPropertiesSet(RepositoryFactoryBeanSupport.java:290) at org.springframework.data.jpa.repository.support.JpaRepositoryFactoryBean.afterPropertiesSet(JpaRepositoryFactoryBean.java:102) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1761) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1698) ... 47 common frames omitted Caused by: java.lang.NullPointerException: null at org.hibernate.hql.internal.ast.HqlSqlWalker.createFromJoinElement(HqlSqlWalker.java:424) at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.joinElement(HqlSqlBaseWalker.java:3931) at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElement(HqlSqlBaseWalker.java:3717) at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElementList(HqlSqlBaseWalker.java:3595) at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromClause(HqlSqlBaseWalker.java:720) at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:576) at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:313) at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:261) at org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:266) at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:189) at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:141) at org.hibernate.engine.query.spi.HQLQueryPlan.(HQLQueryPlan.java:115) at org.hibernate.engine.query.spi.HQLQueryPlan.(HQLQueryPlan.java:77) at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:153) at org.hibernate.internal.AbstractSharedSessionContract.getQueryPlan(AbstractSharedSessionContract.java:553) at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:662) at org.hibernate.internal.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:23) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:350) at com.sun.proxy.$Proxy105.createQuery(Unknown Source) at org.springframework.data.jpa.repository.query.SimpleJpaQuery.validateQuery(SimpleJpaQuery.java:87) ... 76 common frames omitted
提出解决方案我得到了同样的错误
有了这个查询，我也有同样的错误（？！？）
@Query("select us.priceAlertsTapas.tapa from User us ")
这里是User对象：
@Entity @Table(name="t_user") public class User implements Serializable, UserDetails { ... @ManyToMany @JoinTable( name="t_user_price_alert_tapa", joinColumns=@JoinColumn(name="user_id", referencedColumnName="id"), inverseJoinColumns=@JoinColumn(name="price_alert_tapa_id", referencedColumnName="id")) private Set priceAlertsTapas = new HashSet(); }
和
@Entity @Table(name="t_price_alert") public class PriceAlert implements Serializable { /** * */ private static final long serialVersionUID = 1L; public PriceAlert(int id) { super(); this.id = id; } @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Integer id; private String name; ... }
和
@Entity @Table(name="t_price_alert_tapa") public class PriceAlertTapa implements Serializable { /** * */ private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private long id; public PriceAlertTapa(PriceAlert priceAlert, Tapa tapa) { super(); this.tapa = tapa; this.priceAlert = priceAlert; } private Tapa tapa; private PriceAlert priceAlert; .. }
由于priceAlertsTapas已设置，因此您无法使用点路径。
@Query("select us.priceAlertsTapas.tapa from User us")
首先你需要加入它
@Query("select pat.tapa from User us join us.priceAlertsTapas pat")
如果您只对最右边的实体感兴趣，则没有理由使用左（外）连接 – 尽管我不确定这是您的查询validation失败的原因。
我会试试这个：
@Query("select tapa fom PriceAlertsTapas pat join pat.tapa tapa where pat.priceAlert = ?1") List tapasByUserPriceAlert (PriceAlert pa);
如果给定的“tapa”可以与“价格警报”（例如，每个用户一个）有多个关联，那么您将在返回List多次找到它。 解决方案是将返回类型更改为Set或在查询中使用"select distinct...." 。
另一方面，如果您的PriceAlertsTapas是一个简单的多对多关联，那么最好使用@ManyToMany JPA注释，最终使用@JoinTable。 例如，请参见此处 。
你有这个例外，因为你有错误的选择：
us是User
us.priceAlertsTapas已Set
在那之后你想要从中得到tapa但是Set没有这样的领域。