问题
I have JPA entities as outlined here: QueryDSL JPA syntax error with contains on Set?
Now I try to have multiple restrictions on the Set tags in a single query:
Set<Tag> withTags = ...;
Set<Tag> withoutTags = ...;
q.where(license.tags.any().in(withTags));
q.where(license.tags.any().in(withoutTags).not());
When the query is executed I get the following exception:
Exception [EclipseLink-8019] (Eclipse Persistence Services - 2.0.1.v20100213-r6600): org.eclipse.persistence.exceptions.JPQLException
Exception Description: Error compiling the query [select distinct license
from License license
where exists (select license_tags
from Tag license_tags
where license_tags member of license.tags and license_tags = ?1)
and not exists (select license_tags
from Tag license_tags
where license_tags member of license.tags and license_tags = ?2)]
multiple declaration of identification variable [license_tags], previously declared as [Tag license_tags].
I tried to insert as("withTags") into the query but the locations I can do that is is after any() which inserts the the AS in JPQL in the wrong place regarding the duplication problem I am trying to solve. And I can insert it after tags but then I get a SimpleExpression as return on which I cannot execute any().
Any other thoughts how this duplication of identification variable could be prevented?
In addition the statements presented above do only work if the given Set withTags/withoutTags contains only a single value. If multiple values are present the following exception is thrown:
Exception [EclipseLink-6075] (Eclipse Persistence Services - 2.0.1.v20100213-r6600): org.eclipse.persistence.exceptions.QueryException
Exception Description: Object comparisons can only use the equal() or notEqual() operators. Other comparisons must be done through query keys or direct attribute level comparisons.
Expression: [Relation operator IN Base my.package.Tag Parameter 1]
select distinct license
from License license
where exists (select license_tags
from Tag license_tags
where license_tags member of license.tags and license_tags in ?1)
at org.eclipse.persistence.exceptions.QueryException.invalidOperatorForObjectComparison(QueryException.java:614)
at org.eclipse.persistence.internal.expressions.RelationExpression.normalize(RelationExpression.java:393)
at org.eclipse.persistence.internal.expressions.CompoundExpression.normalize(CompoundExpression.java:226)
at org.eclipse.persistence.internal.expressions.CompoundExpression.normalize(CompoundExpression.java:218)
at org.eclipse.persistence.internal.expressions.SQLSelectStatement.normalize(SQLSelectStatement.java:1306)
at org.eclipse.persistence.internal.expressions.SubSelectExpression.normalizeSubSelect(SubSelectExpression.java:134)
at org.eclipse.persistence.internal.expressions.ExpressionNormalizer.normalizeSubSelects(ExpressionNormalizer.java:93)
at org.eclipse.persistence.internal.expressions.SQLSelectStatement.normalize(SQLSelectStatement.java:1379)
at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.buildNormalSelectStatement(ExpressionQueryMechanism.java:482)
at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.prepareSelectAllRows(ExpressionQueryMechanism.java:1553)
at org.eclipse.persistence.queries.ReadAllQuery.prepareSelectAllRows(ReadAllQuery.java:793)
at org.eclipse.persistence.queries.ReadAllQuery.prepare(ReadAllQuery.java:734)
at org.eclipse.persistence.queries.DatabaseQuery.checkPrepare(DatabaseQuery.java:464)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.checkPrepare(ObjectLevelReadQuery.java:732)
at org.eclipse.persistence.queries.DatabaseQuery.prepareCall(DatabaseQuery.java:1577)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.buildEJBQLDatabaseQuery(EJBQueryImpl.java:240)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.buildEJBQLDatabaseQuery(EJBQueryImpl.java:173)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.<init>(EJBQueryImpl.java:125)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.<init>(EJBQueryImpl.java:109)
at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1326)
at sun.reflect.GeneratedMethodAccessor552.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.jboss.weld.util.reflection.SecureReflections$13.work(SecureReflections.java:304)
at org.jboss.weld.util.reflection.SecureReflectionAccess.run(SecureReflectionAccess.java:54)
at org.jboss.weld.util.reflection.SecureReflectionAccess.runAsInvocation(SecureReflectionAccess.java:163)
at org.jboss.weld.util.reflection.SecureReflections.invoke(SecureReflections.java:298)
at org.jboss.weld.bean.proxy.ClientProxyMethodHandler.invoke(ClientProxyMethodHandler.java:113)
at org.jboss.weld.util.CleanableMethodHandler.invoke(CleanableMethodHandler.java:43)
at javax.persistence.EntityManager_$$_javassist_131.createQuery(EntityManager_$$_javassist_131.java)
at com.mysema.query.jpa.impl.DefaultSessionHolder.createQuery(DefaultSessionHolder.java:35)
at com.mysema.query.jpa.impl.AbstractJPAQuery.createQuery(AbstractJPAQuery.java:139)
at com.mysema.query.jpa.impl.AbstractJPAQuery.createQuery(AbstractJPAQuery.java:108)
at com.mysema.query.jpa.impl.AbstractJPAQuery.list(AbstractJPAQuery.java:276)
And with EclipseLink 2.4
Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.4.0.v20120608-r11652): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: org.postgresql.util.PSQLException: The SQL datatype to be used for an instance of mypackage.Tag cannot be determined. Use 'setObject()' with an explizit type, to define it.
Error Code: 0
Call: SELECT DISTINCT t0.ID, ...all the other properties...
FROM LICENSE t0, WHERE ((NOT EXISTS (SELECT ? FROM LicenseTags t5, TAG t4, TAG t3 WHERE (((t3.ID = t4.ID) AND (t3.ID IN (?,?))) AND ((t5.License_ID = t0.ID) AND (t4.ID = t5.tags_ID))))))
For now I tried to work around this by using the following QueryDSL syntax:
for (Tag tag : withTags) {
q.where(license.tags.contains(tag));
}
for (Tag tag : withoutTags) {
q.where(license.tags.contains(tag).not());
}
The former part does work like a charm but the latter does not return the expected results. Licenses with tags present in withoutTags are not excluded from the result set as they should be.
JPQL and SQL for the latter statement look like:
select distinct license
from License license
where not ?1 member of license.tags
SELECT DISTINCT t1.ID, ...all the other properties...
FROM LicenseTags t2, LICENSE t1, TAG t0
WHERE (NOT (133170 = t0.ID) AND (t2.License_ID = t1.ID) AND (t0.ID = t2.tags_ID))
The JPQL looks good to me, but the SQL obviously fails if a license has more than one tag associated with it. So I think this is actually a case where the translation of EclipseLink is failing. I'll have a look if this is a known bug for the version I am using. This thesis is somewhat supported by JPQL "NOT MEMBER OF" query using criteria API though in that case the problem only occurs while using creteria api and not JPQL. This erroneous translation still persists in EclipseLink 2.4 RC 2. Here is finally a workaround that does what it's meant to for the part "without tags":
Collection<Integer> tagIds = new ArrayList<Integer>();
for (Tag tag : withoutTags) {
tagIds.add(tag.getId());
}
q.where(license.tags.any().id.in(tagIds).not());
Regards, Tilmann
回答1:
Can you use a join instead of a sub-select? This would be much more efficient as well.
You could also try EclipseLink 2.4, which may not have these issues.
QueryDSL supports joins, both innerJoin() and leftJoin(), you should use this instead.
回答2:
Currently there are bugs in EclipseLink and QueryDSL that deny usage of the straight forward statements:
q.where(license.tags.any().in(withTags));
q.where(license.tags.any().in(withoutTags).not());
Instead a workaround has to be used:
Collection<Integer> withTagIds = new ArrayList<Integer>();
for (Tag tag : withTags) {
withTagIds.add(tag.getId());
}
q.where(license.tags.any().id.in(withTagIds));
Collection<Integer> withoutTagIds = new ArrayList<Integer>();
for (Tag tag : withoutTags) {
withoutTagIds .add(tag.getId());
}
q.where(license.tags.any().id.in(withoutTagIds ).not());
来源：https://stackoverflow.com/questions/11088064/querydsl-duplicate-identification-variable-equality-syntax-error-with-any-on-set