[hibernate-issues] [Hibernate-JIRA] Commented: (HB-281) ".class" with <joined-subclass> problem

[Stephen M. Wick (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HB-281?page=comments#action_25340 ] 

Stephen M. Wick commented on HB-281:
------------------------------------

The problem appears to be with the implementation of JoinSequence.Selector.includeSubclass(String alias) in JoinProcessor.processJoins(QueryNode query, boolean inSubquery).  JoinSequence.Selector.includeSubclass(String alias) returns false when 'shallowQuery = true', so JoinSequence.addExtraJoins(JoinFragment, String alias, Joinable joinable, boolean innerJoin) passes false to includeSubclasses argument of Joinable.fromJoinFragment(String alias, boolean innerJoin, boolean includeSubclasses).  The method fromJoinFragment is where the join is added to the "from" clause.

I think that the criteria in JoinSequence.Selector.includeSubclass(String alias) should also consider "where" clause components that reference a joined tables or alias.

I hope this info helps.

> ".class" with <joined-subclass> problem
> ---------------------------------------
>
>          Key: HB-281
>          URL: http://opensource.atlassian.com/projects/hibernate/browse/HB-281
>      Project: Hibernate2
>         Type: Bug

>   Components: core
>  Environment: windows 2000
>     Reporter: Simone Ricciardi
>     Priority: Minor

>
>
> I've acknowledged an error that happens using "select count (*) ..." 
> together to a where clause "... where alias.class = ClassName ". 
> Suppose to have two classes: 
> public class Foo
> {
> String id;
> String attr1;
> public String getId(){ return id; }
> public void setId(String id){ this.id = id; }
> public String getAttr1(){ return attr1; }
> public void setAttr1(String attr1){ this.attr1 = attr1; }
> }
> public class Bar extends Foo
> {
> String attr2;
> public String getAttr2(){ return attr2; }
> public void setAttr2(String attr2){ this.attr2 = attr2; }
> }
> and the corresponding mapping file: 
> <hibernate-mapping>
> <class name="test.persistents.Foo" table="Foo">
> <id name="id" type="string">
> <column name="id" length="32"/>
> <generator class="uuid.hex"/>
> </id>
> <property name="attr1" column="attr1" type="string"/>
> <joined-subclass name="test.persistents.Bar" table="Bar">
> <key column="foo_id"/>
> <property name="attr2" column="attr2" type="string"/>
> </joined-subclass>
> </class>
> </hibernate-mapping>
> When I try to make the following query: 
> Query query = session.createQuery("select count(*) from Foo foo where foo.class = Foo"); 
> I get an error of this type:
> java.sql.SQLException: General error, message from server: "Unknown table 'foo0__1' in where clause"
> at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:1651)
> at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:889)
> at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:956)
> at com.mysql.jdbc.Connection.execSQL(Connection.java:1874)
> at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1538)
> at com.p6spy.engine.logging.P6LogPreparedStatement.executeQuery(P6LogPreparedStatement.java:171)
> at net.sf.hibernate.impl.BatcherImpl.getResultSet(BatcherImpl.java:71)
> at net.sf.hibernate.loader.Loader.getResultSet(Loader.java:551)
> at net.sf.hibernate.loader.Loader.doFind(Loader.java:140)
> at net.sf.hibernate.loader.Loader.find(Loader.java:620)
> at net.sf.hibernate.hql.QueryTranslator.find(QueryTranslator.java:928)
> at net.sf.hibernate.impl.SessionImpl.find(SessionImpl.java:1343)
> at net.sf.hibernate.impl.QueryImpl.list(QueryImpl.java:76)
> at test.Test.main(Test.java:42)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
> at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> at java.lang.reflect.Method.invoke(Method.java:324)
> while if I perform the same query without the select count(*) (select foo from Foo foo where foo.class = Foo) 
> all works fine.
> Comparing the two queries produced by hibernate in both cases, 
> it seems that the error derives from the lack of the "left outer join" with the Bar table in the "from" clause:
> with select count(*):
> select count(*) as x0_0_ 
> from Foo foo0_ 
> where (case when foo0__1.foo_id is not null then 1 when foo0_.id is not null then 0 end=0 )
> without select count(*):
> select foo0_.id as id, 
> case when foo0__1.foo_id is not null then 1 
> when foo0_.id is not null then 0 end 
> as clazz_, 
> foo0_.attr1 as attr10_, 
> foo0__1.attr2 as attr21_ 
> from Foo foo0_ left outer join Bar foo0__1 on foo0_.id=foo0__1.foo_id 
> where (case when foo0__1.foo_id is not null then 1 when foo0_.id is not null then 0 end=0 )
> in fact the query should be the following:
> select count(*) as x0_0_ 
> from Foo foo0_ left outer join Bar foo0__1 on foo0_.id=foo0__1.foo_id 
> where (case when foo0__1.foo_id is not null then 1 when foo0_.id is not null then 0 end=0 )

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