[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-2891) Query cache fails on many-to-many select

[Gail Badner (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2891?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_28436 ] 

Gail Badner commented on HHH-2891:
----------------------------------

Please attach a runnable test case (Java + mapping).

> Query cache fails on many-to-many select
> ----------------------------------------
>
>                 Key: HHH-2891
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2891
>             Project: Hibernate3
>          Issue Type: Bug
>          Components: query-hql
>    Affects Versions: 3.2.5
>            Reporter: Oleg Efimov
>
> I have two entities, User and Group, with many-to-many relation:
> -------------------------------------------------------------------------------------------------- User.hbm.xml
> <?xml version="1.0"?>
> <!DOCTYPE hibernate-mapping PUBLIC
>         "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
>         "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
> <hibernate-mapping package="test.hibernate">
>     <class name="User" table="`USER`">
>         <id name="id" type="long" unsaved-value="null">
>             <column name="USER_ID" not-null="true"/>
>             <generator class="native"/>
>         </id>
>         <property name="login">
>             <column name="LOGIN" not-null="true" length="255"/>
>         </property>
>         <bag name="groups" table="USER_GROUP" lazy="false" cascade="none">
>             <key column="USER_ID"/>
>             <many-to-many class="Group" column="GROUP_ID"/>
>         </bag>
>     </class>
> </hibernate-mapping>
> -------------------------------------------------------------------------------------------------- Group.hbm.xml
> <?xml version="1.0"?>
> <!DOCTYPE hibernate-mapping PUBLIC
>         "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
>         "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
> <hibernate-mapping package="test.hibernate">
>     <class name="Group" table="`GROUP`">
>         <id name="id" type="long" unsaved-value="null">
>             <column name="GROUP_ID" not-null="true"/>
>             <generator class="native"/>
>         </id>
>         <property name="name">
>             <column name="GROUPNAME" not-null="true" length="100"/>
>         </property>
>         <bag name="users" table="USER_GROUP" lazy="true" inverse="true" cascade="all-delete-orphan">
>             <key column="GROUP_ID"/>
>             <many-to-many class="User" column="USER_ID"/>
>         </bag>
>     </class>
>     <query name="Group.select.by.login" cacheable="true"><![CDATA[
>         select user.groups from User user where user.login=?
>     ]]>
>     </query>
> </hibernate-mapping>
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> test.hibernate.User and test.hibernate.Group classes are just simple beans.
> In Group.hbm.xml there is a query called "Group.select.by.login", it's intended to be cached. So I add corresponding properties to Hibernate configuraition:
> --------------------------------------------------------------------------------------------------
>         properties.put("hibernate.cache.provider_class",  "org.hibernate.cache.EhCacheProvider");
>         properties.put("hibernate.cache.use_query_cache", "true");
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> Configuration has no extra parameters.
> Then I'm trying to execute the query two times:
> -------------------------------------------------------------------------------------------------- test fragment 
>         SessionFactory sessionFactory = configuration.buildSessionFactory();
>         Session session = null;
>         try {
>             session = sessionFactory.openSession();
>             Query query = session.getNamedQuery("Group.select.by.login");
>             List<Group> groups;
>             groups = query.setParameter(0, "admin").list(); // +++++++++++++++This list() returns list of two Group objects, ok +++++++++++++++
>             System.out.println("-----------------------------------------------------------------------------------");
>             for (Group group : groups) {
>                 System.out.println(group.getName());
>             }
>             System.out.println("-----------------------------------------------------------------------------------");
>             groups = query.setParameter(0, "admin").list(); // +++++++++++++++This list() returns list of two nulls +++++++++++++++
>             System.out.println("-----------------------------------------------------------------------------------");
>             for (Group group : groups) {
>                 System.out.println(group.getName());
>             }
>             System.out.println("-----------------------------------------------------------------------------------");
>         } finally {
>             if (session != null) {
>                 session.close();
>             }
>             sessionFactory.close();
>         }
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> The first query returns list of, in my case, two groups. The second query returns list of two nulls instead of the same list.
> I've investigated the problem, and found the following:
> Query return value is "user.groups", and during query analysis (org.hibernate.hql.ast.QueryTranslatorImpl:160) query return type is defined as "org.hibernate.type.BagType(test.hibernate.User.groups)". This seems to be the problem, as during query put operation org.hibernate.CollectionType.disassemble is called (org.hibernate.cache.StandardQueryCache:80), which simply returns null as owner is null.
> If this query is not a misuse, then I think, something is to be done at the time of analysis, so that return type be somewhat different.
> Thanks.

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