JPQL：在 EclipseLink 上导致奇怪异常的 SIZE 函数答案

【问题标题】：JPQL: SIZE function causing strange exceptions on EclipseLinkJPQL：在 EclipseLink 上导致奇怪异常的 SIZE 函数
【发布时间】：2012-03-19 00:00:39
【问题描述】：

我从 Hibernate 移植。 JPQL 语句中的 SIZE 函数有什么问题（假设映射正确）？：

SELECT NEW de.poyry.pqgenerator.view.PqListItem(
 pq.id,
 pq.name,
 pq.submissionDate,
 pe.firstName,
 pe.lastName,
 SIZE(pa))
FROM Prequalification pq
 JOIN pq.user us
 JOIN us.person pe
 LEFT JOIN pq.partnerships pa
 LEFT JOIN pa.company co
GROUP BY pq.id

这是构造函数签名（唯一的构造函数）：

public PqListItem(Integer id, String name, Date submissionDate,
                  String ownerFirstName, String ownerLastName,
                  Integer numPartnerships)

查询结果：

Caused by: Exception [EclipseLink-8023] (Eclipse Persistence Services - 2.3.0.v20110604-r9504): org.eclipse.persistence.exceptions.JPQLException
Exception Description: Syntax error parsing the query [^^...].
Internal Exception: org.eclipse.persistence.internal.libraries.antlr.runtime.EarlyExitException
    at org.eclipse.persistence.exceptions.JPQLException.syntaxError(JPQLException.java:352)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.JPQLParser.handleRecognitionException(JPQLParser.java:354)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.JPQLParser.addError(JPQLParser.java:246)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.JPQLParser.reportError(JPQLParser.java:363)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.pathExpression(JPQLParser.java:2894)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.collectionValuedPathExpression(JPQLParser.java:2624)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.size(JPQLParser.java:7660)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.functionsReturningNumerics(JPQLParser.java:6710)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.arithmeticPrimary(JPQLParser.java:4762)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.arithmeticFactor(JPQLParser.java:4660)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.arithmeticTerm(JPQLParser.java:4546)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.simpleArithmeticExpression(JPQLParser.java:4462)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.scalarExpression(JPQLParser.java:4834)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.constructorItem(JPQLParser.java:1980)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.constructorExpression(JPQLParser.java:1849)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.selectExpression(JPQLParser.java:1300)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.selectItem(JPQLParser.java:1169)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.selectClause(JPQLParser.java:1081)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.selectStatement(JPQLParser.java:359)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.document(JPQLParser.java:281)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.JPQLParser.parse(JPQLParser.java:134)
    at org.eclipse.persistence.internal.jpa.parsing.jpql.JPQLParser.buildParseTree(JPQLParser.java:95)
    at org.eclipse.persistence.internal.jpa.EJBQueryImpl.buildEJBQLDatabaseQuery(EJBQueryImpl.java:215)
    at org.eclipse.persistence.internal.jpa.EJBQueryImpl.buildEJBQLDatabaseQuery(EJBQueryImpl.java:190)
    at org.eclipse.persistence.internal.jpa.EJBQueryImpl.<init>(EJBQueryImpl.java:142)
    at org.eclipse.persistence.internal.jpa.EJBQueryImpl.<init>(EJBQueryImpl.java:126)
    at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1475)
    ... 139 more
Caused by: org.eclipse.persistence.internal.libraries.antlr.runtime.EarlyExitException
    at org.eclipse.persistence.internal.jpa.parsing.jpql.antlr.JPQLParser.pathExpression(JPQLParser.java:2882)
    ... 161 more

SIZE(pa) 似乎会引起问题。当更改为SIZE(pq.partnerships) 时，我得到：

Caused by: Exception [EclipseLink-6137] (Eclipse Persistence Services - 2.3.0.v20110604-r9504): org.eclipse.persistence.exceptions.QueryException
Exception Description: An Exception was thrown while executing a ReportQuery with a constructor expression: java.lang.NoSuchMethodException: de.poyry.pqgenerator.view.PqListItem.<init>(java.lang.Integer, java.lang.String, java.util.Date, java.lang.String, java.lang.String, int)
Query: ReportQuery(referenceClass=Prequalification jpql="SELECT NEW de.poyry.pqgenerator.view.PqListItem(pq.id, pq.name, pq.submissionDate, pe.firstName, pe.lastName, SIZE(pq.partnerships)) FROM Prequalification pq  JOIN pq.user us  JOIN us.person pe  LEFT JOIN pq.partnerships pa  LEFT JOIN pa.company co GROUP BY pq.id")
Default FetchGroup(){id, partnerships, submissionDate, nodes, designSheets, name, statuses, group, user, tendering, isLocked}
    at org.eclipse.persistence.exceptions.QueryException.exceptionWhileUsingConstructorExpression(QueryException.java:494)
    at org.eclipse.persistence.queries.ConstructorReportItem.initialize(ConstructorReportItem.java:188)
    at org.eclipse.persistence.queries.ReportQuery.prepare(ReportQuery.java:1044)
    at org.eclipse.persistence.queries.DatabaseQuery.checkPrepare(DatabaseQuery.java:598)
    at org.eclipse.persistence.queries.ObjectLevelReadQuery.checkPrepare(ObjectLevelReadQuery.java:839)
    at org.eclipse.persistence.queries.DatabaseQuery.prepareCall(DatabaseQuery.java:1719)
    at org.eclipse.persistence.internal.jpa.EJBQueryImpl.buildEJBQLDatabaseQuery(EJBQueryImpl.java:268)
    at org.eclipse.persistence.internal.jpa.EJBQueryImpl.buildEJBQLDatabaseQuery(EJBQueryImpl.java:190)
    at org.eclipse.persistence.internal.jpa.EJBQueryImpl.<init>(EJBQueryImpl.java:142)
    at org.eclipse.persistence.internal.jpa.EJBQueryImpl.<init>(EJBQueryImpl.java:126)
    at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1475)
    at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1497)
    at com.sun.enterprise.container.common.impl.EntityManagerWrapper.createQuery(EntityManagerWrapper.java:468)
    at de.poyry.pqgenerator.service.PqService.findAllPqs(PqService.java:60)
    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.glassfish.ejb.security.application.EJBSecurityManager.runMethod(EJBSecurityManager.java:1052)
    at org.glassfish.ejb.security.application.EJBSecurityManager.invoke(EJBSecurityManager.java:1124)
    at com.sun.ejb.containers.BaseContainer.invokeBeanMethod(BaseContainer.java:5366)
    at com.sun.ejb.EjbInvocation.invokeBeanMethod(EjbInvocation.java:619)
    at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800)
    at com.sun.ejb.EjbInvocation.proceed(EjbInvocation.java:571)
    at org.jboss.weld.ejb.SessionBeanInterceptor.aroundInvoke(SessionBeanInterceptor.java:46)
    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 com.sun.ejb.containers.interceptors.AroundInvokeInterceptor.intercept(InterceptorManager.java:861)
    at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800)
    at com.sun.ejb.EjbInvocation.proceed(EjbInvocation.java:571)
    at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.doAround(SystemInterceptorProxy.java:162)
    at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.aroundInvoke(SystemInterceptorProxy.java:144)
    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 com.sun.ejb.containers.interceptors.AroundInvokeInterceptor.intercept(InterceptorManager.java:861)
    at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800)
    at com.sun.ejb.containers.interceptors.InterceptorManager.intercept(InterceptorManager.java:370)
    at com.sun.ejb.containers.BaseContainer.__intercept(BaseContainer.java:5338)
    at com.sun.ejb.containers.BaseContainer.intercept(BaseContainer.java:5326)
    at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:214)
    ... 106 more

看起来好像没有自动装箱？最后一个构造函数参数的类型是整数。奇怪，它应该可以在 IMO 中使用。

有人可以帮忙吗？我在 GlassFish 3.1.1 上使用 EclipseLink 2.3.2。

您如何从查询中正确确定合作伙伴的数量？ JPA 在这里定义了什么？

【问题讨论】：

标签： java jpa collections eclipselink jpql

【解决方案1】：

SIZE 函数在 jpa 规范中定义为

functions_returning_numerics::=
    SIZE(collection_valued_path_expression)

collection_valued_path_expression ::=
    general_identification_variable.{single_valued_object_field.}*collection_valued_field

这意味着您必须将实际属性传递给SIZE 函数，而不仅仅是变量名。您可以尝试以下查询吗：

SELECT NEW de.poyry.pqgenerator.view.PqListItem(
 pq.id,
 pq.name,
 pq.submissionDate,
 pe.firstName,
 pe.lastName,
 SIZE(pq.partnerships))
FROM Prequalification pq
 JOIN pq.user us
 JOIN us.person pe
GROUP BY pq.id, pq.name, pq.submissionDate, pe.firstName, pe.lastName

请注意，我还删除了 pa.company 和 pq.partnerships 的连接，因为它们没有被使用，并按照 JPA 和 SQL 标准的要求将非聚合字段添加到 GROUP BY 表达式。

使用GROUP BY时SELECT子句的要求遵循SQL的要求：即任意出现在 SELECT 子句中的项目（除了作为聚合函数或作为聚合函数）也必须出现在GROUP BY 子句中。

【讨论】：

我只是不明白为什么我需要 GROUP BY 中的 , pq.name, pq.submissionDate, pe.firstName, pe.lastName 字段，因为只有 pq.id 产生相同的 PQ 项目列表。

【解决方案2】：

如果您添加一个采用 int 而不是 Integer 的构造函数，它会起作用吗？这似乎是问题所在。

我认为这在 EclipseLink 2.4 流中已修复，Integer 或 int 现在应该可以工作了。

【讨论】：