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wchess
 Post subject: Import XML data (parent/child) using dom4j without ids
PostPosted: Thu Mar 15, 2007 8:16 pm 
Newbie

Joined: Thu Mar 15, 2007 7:25 pm
Posts: 2
I'm attempting to import XML data for objects without ids. I'm hoping that hibernate has the capability to create native keys on the fly for objects represented as dom4j elements.

My existing code works quite well for any data that i comes from my export (i.e. has ids), but it fails when i attempt to "replicate" an element that does not have a non-null id field. As i show in the 1st stack trace.
I've also attempted the code with "save" call instead of "replicate", for which i get a different exception (2nd stack trace).

The "replicate()" code works when i have ids, but clearly is not very close to working when there are no ids.
The "save()" code seems much closer, in that as can be seen in the logs, there seems to be some issue about the child object's reference to it's parent. I'm all for removing it from XML representation... i have embed-xml set to false, so that it is minimized to an id, but... well that still seems to be a problem.
I would prefer not to have to add a "node=xxx" everywhere except the alpha element, and i'm not even sure that would work.

I hope this is possible (and a simple tweak), and any help would be greatly appreciated.
thanks
-w


Data with ids
Code:
<?xml version="1.0" encoding="UTF-8"?>
<objects>
<Alpha>
    <id>100</id>
    <name>test alpha</name>
    <betas>
      <Beta>
        <id>101</id>
        <name>beta one</name>
        <alpha>100</alpha>
      </Beta>
      <Beta>
        <id>102</id>
        <name>beta two</name>
        <alpha>100</alpha>
      </Beta>
    </betas>
  </Alpha>
</objects>

Data without ids
Code:
<?xml version="1.0" encoding="UTF-8"?>
<objects>
<Alpha>
    <name>test alpha</name>
    <betas>
      <Beta>
        <name>beta one</name>
      </Beta>
      <Beta>
        <name>beta two</name>
      </Beta>
    </betas>
  </Alpha>
</objects>


Hibernate version:
3.2.0

Mapping documents:

Alpha.hbm.xml
Code:
<?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="example">
    <class name="Alpha" table="Alpha">
        <cache usage="nonstrict-read-write" />
        <id name="id" type="long" column="Id">
            <generator class="native"/>
        </id>
        <property name="name" type="string" unique="true">
            <meta attribute="use-in-tostring">true</meta>
            <column name="NAME" not-null="true" unique="true" unique-key="alpha_name_u1" />
        </property>
        <set name="betas" table="Beta" cascade="all" lazy="false" inverse="true">
            <key column="BetaId" />
            <one-to-many class="Beta" node="Beta"/>
        </set>
    </class>
</hibernate-mapping>


Beta.hbm.xml
Code:
<?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="example">
    <class name="Beta" table="Beta">
        <cache usage="nonstrict-read-write" />
        <id name="id" type="long" column="Id">
            <generator class="native"/>
        </id>
        <property name="name" type="string" unique="true">
            <meta attribute="use-in-tostring">true</meta>
            <column name="NAME" not-null="true" unique="true" unique-key="beta_name_u1" />
        </property>
        <many-to-one name="alpha" class="Alpha" column="ALPHAID"
                    not-null="true" embed-xml="false"/>
    </class>
</hibernate-mapping>


Code between sessionFactory.openSession() and session.close():
Code:
            String      pkg         = "example.";
            Document    document;
            Element     root;
            SAXReader   reader = new SAXReader();
   
            document = reader.read( is );
            root = document.getRootElement();
   
            Transaction t = domsession.beginTransaction();
            for( Object o : root.elements() )
            {
                Element child = (Element) o;
                //domsession.save( pkg + child.getQName().getName(), child );
                domsession.replicate( pkg + child.getQName().getName(),
                                      child,
                                      ReplicationMode.OVERWRITE );
            }
            t.commit();


Full stack trace of any exception that occurs:
Stack Trace 1 (replicate)
Code:
ERROR 2007-03-15 16:04:51,611 [PoolThread-9] - example.XmlImporter - Exception during import:
org.hibernate.TransientObjectException: instance with null id passed to replicate()
        at org.hibernate.event.def.DefaultReplicateEventListener.onReplicate(DefaultReplicateEventListener.java:66)
        at org.hibernate.impl.SessionImpl.fireReplicate(SessionImpl.java:932)
        at org.hibernate.impl.SessionImpl.replicate(SessionImpl.java:924)
        at example.XmlImporter.doImport(XmlImporter.java:91)
        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:585)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:281)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:187)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:154)
        at org.springframework.orm.hibernate3.HibernateInterceptor.invoke(HibernateInterceptor.java:104)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:176)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:210)
        at $Proxy24.doImport(Unknown Source)


Stack Trace 2 (save)
Code:
ERROR 2007-03-15 16:59:38,267 [PoolThread-7] - example.XmlImporter - Exception during import:
org.hibernate.PropertyValueException: not-null property references a null or transient value: example.Beta.alpha
        at org.hibernate.engine.Nullability.checkNullability(Nullability.java:72)
        at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:284)
        at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:180)
        at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:121)
        at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:186)
        at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:175)
        at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:98)
        at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
        at org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java:507)
        at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:499)
        at org.hibernate.engine.CascadingAction$1.cascade(CascadingAction.java:218)
        at org.hibernate.engine.Cascade.cascadeToOne(Cascade.java:268)
        at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:216)
        at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:169)
        at org.hibernate.engine.Cascade.cascadeCollectionElements(Cascade.java:296)
        at org.hibernate.engine.Cascade.cascadeCollection(Cascade.java:242)
        at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:219)
        at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:169)
        at org.hibernate.engine.Cascade.cascade(Cascade.java:130)
        at org.hibernate.event.def.AbstractSaveEventListener.cascadeAfterSave(AbstractSaveEventListener.java:437)
        at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:326)
        at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:180)
        at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:121)
        at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:186)
        at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:33)
        at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:175)
        at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:27)
        at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
        at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:535)
        at org.hibernate.impl.SessionImpl.save(SessionImpl.java:523)
        at exmaple.XmlImporter.doImport(XmlImporter.java:92)
        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:585)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:281)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:187)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:154)
        at org.springframework.orm.hibernate3.HibernateInterceptor.invoke(HibernateInterceptor.java:104)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:176)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:210)
        at $Proxy24.doImport(Unknown Source)



Name and version of the database you are using:
postgresql 8.1.3

The generated SQL (show_sql=true):
SQL 1 (replicate)
NONE. fails before SQL is generated

SQL 2 (save)
Hibernate: select nextval ('public.hibernate_sequence')
Hibernate: select nextval ('public.hibernate_sequence')

Debug level Hibernate log excerpt:
debug 1 (replicate)
DEBUG 2007-03-15 16:56:25,220 [PoolThread-8] - org.hibernate.impl.SessionImpl - opened session at timestamp: 4808716227457024
DEBUG 2007-03-15 16:56:27,086 [PoolThread-8] - org.hibernate.impl.SessionImpl - opened session [dom4j]
WARN 2007-03-15 16:56:29,686 [PoolThread-8] - org.hibernate.impl.SessionImpl - Transaction started on non-root session
DEBUG 2007-03-15 16:56:29,688 [PoolThread-8] - org.hibernate.transaction.JDBCTransaction - begin
DEBUG 2007-03-15 16:56:29,689 [PoolThread-8] - org.hibernate.jdbc.ConnectionManager - opening JDBC connection
DEBUG 2007-03-15 16:56:29,689 [PoolThread-8] - org.hibernate.transaction.JDBCTransaction - current autocommit status: false

debug 2 (save)
DEBUG 2007-03-15 16:59:31,263 [PoolThread-7] - org.hibernate.impl.SessionImpl - opened session at timestamp: 4808716989493248
DEBUG 2007-03-15 16:59:31,756 [PoolThread-7] - org.hibernate.impl.SessionImpl - opened session [dom4j]
WARN 2007-03-15 16:59:33,638 [PoolThread-7] - org.hibernate.impl.SessionImpl - Transaction started on non-root session
DEBUG 2007-03-15 16:59:33,639 [PoolThread-7] - org.hibernate.transaction.JDBCTransaction - begin
DEBUG 2007-03-15 16:59:33,639 [PoolThread-7] - org.hibernate.jdbc.ConnectionManager - opening JDBC connection
DEBUG 2007-03-15 16:59:33,640 [PoolThread-7] - org.hibernate.transaction.JDBCTransaction - current autocommit status: false
DEBUG 2007-03-15 16:59:35,646 [PoolThread-7] - org.hibernate.jdbc.AbstractBatcher - about to open PreparedStatement (open PreparedStatements: 0, globally: 0)
DEBUG 2007-03-15 16:59:35,647 [PoolThread-7] - org.hibernate.SQL - select nextval ('public.hibernate_sequence')
DEBUG 2007-03-15 16:59:35,651 [PoolThread-7] - org.hibernate.id.SequenceGenerator - Sequence identifier generated: 91012
DEBUG 2007-03-15 16:59:35,652 [PoolThread-7] - org.hibernate.jdbc.AbstractBatcher - about to close PreparedStatement (open PreparedStatements: 1, globally: 1)
DEBUG 2007-03-15 16:59:35,653 [PoolThread-7] - org.hibernate.event.def.AbstractSaveEventListener - generated identifier: 91012, using strategy: org.hibernate.id.SequenceGenerator
DEBUG 2007-03-15 16:59:35,680 [PoolThread-7] - org.hibernate.jdbc.AbstractBatcher - about to open PreparedStatement (open PreparedStatements: 0, globally: 0)
DEBUG 2007-03-15 16:59:35,681 [PoolThread-7] - org.hibernate.SQL - select nextval ('public.hibernate_sequence')
DEBUG 2007-03-15 16:59:35,683 [PoolThread-7] - org.hibernate.id.SequenceGenerator - Sequence identifier generated: 91013
DEBUG 2007-03-15 16:59:35,684 [PoolThread-7] - org.hibernate.jdbc.AbstractBatcher - about to close PreparedStatement (open PreparedStatements: 1, globally: 1)
DEBUG 2007-03-15 16:59:35,684 [PoolThread-7] - org.hibernate.event.def.AbstractSaveEventListener - generated identifier: 91013, using strategy: org.hibernate.id.SequenceGenerator
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vsnaveen1
 Post subject: Re: Import XML data (parent/child) using dom4j without ids
PostPosted: Sat May 01, 2010 9:26 am 
Newbie

Joined: Sat May 01, 2010 9:20 am
Posts: 6
Hi
I have a problem with retrieving the data in xml format (when I open the session in DOM4J MODE).

I have to get a complex structured xml for example

<parent>
........
<child>........</child>
<child>........</child>
<child>........</child>
......
</parent>

so for the above scenario I have to make the attribute <embed-xml = 'true'> in the parent.hbm.xml

But if I do that I am getting a stack over flow error because it is trying to fetch so many records..

Do you have any solution for this?
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wchess
 Post subject: Re: Import XML data (parent/child) using dom4j without ids
PostPosted: Sat May 01, 2010 1:48 pm 
Newbie

Joined: Thu Mar 15, 2007 7:25 pm
Posts: 2
vsnaveen1,

do you have embed-xml set to false in the child?
it's been a long time since i delt with hibernate (never solved the above issue anyway).

But, you getting a stack overflow is suspicious, b/c i would expect "too many elements" to give you an oom not a stack overflow. However, if you try to embed xml in both parent and child, that would stack overflow for 'obvious' reasons. If you haven't set it explicitly to false, i'd try that (in the child mapping file).
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