[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-2225) NPE when eager fetching joined component with native SQL query

[Mihail Fridliand (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2225?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_27605 ] 

Mihail Fridliand commented on HHH-2225:
---------------------------------------

This seems to be a general problem when using components in the native SQL. Suppose, the have class "A" containing a component class "Component" containing a collection of "B"

public class A {
	private Long oid;
	private Component comp = new Component();
	
	public Component getComp() {return comp;}
	public void setComp(Component comp) {this.comp = comp;}
	
	public Long getOid() {	return oid;}	
	public void setOid(Long oid) {this.oid = oid;}
}

public class Component {
	private Set collection = new HashSet(0);

	public Set getCollection() {	return collection;}
	public void setCollection(Set collection) {	this.collection = collection;}
}

public class B {
	private Long oid;
	public Long getOid() {	return oid;}
	public void setOid(Long oid) {this.oid = oid;}
}

the mappings test1.hbm.xml: 

<hibernate-mapping>
 	<class name="A" table="A" >
      <id name="oid" type="java.lang.Long">
            <column name="OID" />
             <generator class="assigned" />       
        </id>
       
       <component name="comp" class="Component">
         <set name="collection" inverse="true" cascade="all">
            <key>
                <column name="A_OID" not-null="true" />
            </key>
            <one-to-many class="B" />
        </set>
       </component>
   </class>
   
   <class name="B" table="B" >
      	<id name="oid" type="java.lang.Long">
            <column name="OID" />
             <generator class="assigned" />
        </id>
   </class>
   
   <resultset name="AandB">
		  <return alias="a" class="A"/>
   		   <return-join alias="ac" property="a.comp"/>
   		  <return-join alias="b" property="ac.collection"/>
	</resultset>
  
  <sql-query  name="getAandB"  resultset-ref="AandB"  	>
         <![CDATA[
          	select DISTINCT {a.*},{b.*} from  A a	join B b on a.OID = b.A_OID			
         ]]>
	</sql-query>
</hibernate-mapping>

For this simple case I get a NPE

java.lang.NullPointerException
	at org.hibernate.loader.custom.sql.SQLQueryReturnProcessor.processJoinReturn(SQLQueryReturnProcessor.java:434)
	at org.hibernate.loader.custom.sql.SQLQueryReturnProcessor.processReturn(SQLQueryReturnProcessor.java:338)
	at org.hibernate.loader.custom.sql.SQLQueryReturnProcessor.process(SQLQueryReturnProcessor.java:148)
	at org.hibernate.loader.custom.sql.SQLCustomQuery.<init>(SQLCustomQuery.java:64)
	at org.hibernate.engine.query.NativeSQLQueryPlan.<init>(NativeSQLQueryPlan.java:43)
	at org.hibernate.engine.query.QueryPlanCache.getNativeSQLQueryPlan(QueryPlanCache.java:114)
	at org.hibernate.impl.SessionFactoryImpl.checkNamedQueries(SessionFactoryImpl.java:444)
	at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:351)
	at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1291)
	at com.dcx.ivkmds.fwk.pc.hibernate.HibernateUtil.rebuildSessionFactory(HibernateUtil.java:191)
	at com.dcx.ivkmds.fwk.pc.hibernate.HibernateUtil.<clinit>(HibernateUtil.java:59)

The NPE is caused by the following code in the SQLQueryReturnProcessor class:

private void processJoinReturn(NativeSQLQueryJoinReturn fetchReturn) {
.....
              // If this return's alias has not been processed yet, do so b4 further processing of this return
		if ( !alias2Persister.containsKey( ownerAlias ) ) {
			NativeSQLQueryNonScalarReturn ownerReturn = ( NativeSQLQueryNonScalarReturn ) alias2Return.get(ownerAlias);
			processReturn( ownerReturn );
		}

		SQLLoadable ownerPersister = ( SQLLoadable ) alias2Persister.get( ownerAlias );
		Type returnType = ownerPersister.getPropertyType( fetchReturn.getOwnerProperty() );
.....

When  the property  ac.collection is processed, there is no for the component Component (ownerAlias = "ac"). Therefore processReturn(ownerReturn) is invoked. But processReturn ignores component types. Then  
                alias2Persister.get(ownerAlias)
still have no entry for the ownerAlias => ownerPersister is null => NullPointerException at the next line.

If I change the resultset to (my first try)

     <resultset name="AandB">
		  <return alias="a" class="A"/>
   		  <return-join alias="b" property="a.comp.collection"/>
	</resultset>

and try to relate to the collection of B's directly, I get 

      org.hibernate.HibernateException: Owner alias [a.comp] is unknown for alias [b]
	at org.hibernate.loader.custom.sql.SQLQueryReturnProcessor.processJoinReturn(SQLQueryReturnProcessor.java:424)
	at org.hibernate.loader.custom.sql.SQLQueryReturnProcessor.processReturn(SQLQueryReturnProcessor.java:338)
	at org.hibernate.loader.custom.sql.SQLQueryReturnProcessor.process(SQLQueryReturnProcessor.java:148)
	at org.hibernate.loader.custom.sql.SQLCustomQuery.<init>(SQLCustomQuery.java:64)

What is wrong ??


> NPE when eager fetching joined component with native SQL query
> --------------------------------------------------------------
>
>                 Key: HHH-2225
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2225
>             Project: Hibernate3
>          Issue Type: Bug
>          Components: query-sql
>    Affects Versions: 3.2.0.ga
>            Reporter: Christian Bauer
>            Priority: Minor
>
> Item -> many-to-one -> User -> joined component -> billingAddress
> This:
>  result = session.createSQLQuery("select {i.*}, {u.*}, {ba.*} from ITEM i" +
>                                         " join USERS u on i.SELLER_ID = u.USER_ID" +
>                                         " left join BILLING_ADDRESS ba on u.USER_ID = ba.USER_ID" +
>                                         " where u.USERNAME = :uname")
>                          .addEntity("i", Item.class)
>                          .addJoin("u", "i.seller")
>                          .addJoin("ba", "u.billingAddress")
> fails with:
> java.lang.NullPointerException
> 	at org.hibernate.loader.DefaultEntityAliases.<init>(DefaultEntityAliases.java:37)
> 	at org.hibernate.loader.custom.sql.SQLQueryReturnProcessor.generateCustomReturns(SQLQueryReturnProcessor.java:283)
> 	at org.hibernate.loader.custom.sql.SQLCustomQuery.<init>(SQLCustomQuery.java:129)
> 	at org.hibernate.engine.query.NativeSQLQueryPlan.<init>(NativeSQLQueryPlan.java:43)
> 	at org.hibernate.engine.query.QueryPlanCache.getNativeSQLQueryPlan(QueryPlanCache.java:114)
> 	at org.hibernate.impl.AbstractSessionImpl.getNativeSQLQueryPlan(AbstractSessionImpl.java:137)
> 	at org.hibernate.impl.AbstractSessionImpl.list(AbstractSessionImpl.java:142)
> 	at org.hibernate.impl.SQLQueryImpl.list(SQLQueryImpl.java:150)

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