nicorrect XML being generated - node repeated

donall05 · **Joined:** Mon May 09, 2005 7:57 am **Posts:** 5

hello.
i'm (new to hibernate and) using verion 3.0.1 to generate an XML view of my data in Sybase 12, using jdk1.4.2_04.

it seems to work fairly fine for me (i still have to tweak some mappings), except that i have a type called TaskItem, which has two associations to classes OF THE SAME TYPE: TaskEvent.
one association is called "taskEventByCreateEventId" and the other is called "taskEventByLastEventId". both these names are sniffed from the foreign keys in the database schema, by MiddleGen2.1.

now, when i do a retrieval from the database, the generated XML document correctly retrieves all the data i want, but the TaskItem node (the root node) has two sub-elements called either "taskEventByCreateEventId" or "taskEventByLastEventId". the name depends on which association i have defined second in my TaskItem.hbm descriptor. what i want is one association called "taskEventByCreateEventId" and one called "taskEventByLastEventId".

note that this only happens if i specify the attribute embed-xml="true" FOR BOTH ASSOCIATIONS. if i set embed-xml="false", even for only one of the associations, then the associations (nodes in my XML doc) are named correctly!

and it only happens if the referenced TaskEvents have the same ID.

is there some config which i am neglecting, or some optimisation that is happening that i don't know about?

find below the relevant sections of config files.

many thanks.
donall.

from TaskItem.hbm:

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>
<!-- 
    Created by the Middlegen Hibernate plugin 2.1

    http://boss.bekk.no/boss/middlegen/
    http://www.hibernate.org/
-->

<class 
    name="com.ebzc.utils.taskpersistence.TaskItem" 
    table="TASK_ITEM"
    node="TaskItem"
>
    <meta attribute="class-description" inherit="false">
       @hibernate.class
        table="TASK_ITEM"
    </meta>

    <!-- bi-directional many-to-one association to TaskEvent -->
    <many-to-one
        name="taskEventByLastEventId"
        class="com.blah.TaskEvent"
        not-null="true"
        embed-xml="true"
    >
        <meta attribute="field-description">
           @hibernate.many-to-one
            not-null="true"
           @hibernate.column name="LAST_EVENT_ID"         
        </meta>
        <column name="LAST_EVENT_ID" />
    </many-to-one>
    <!-- bi-directional many-to-one association to TaskEvent -->
    <many-to-one
        name="taskEventByCreateEventId"
        class="com.blah.TaskEvent"
        not-null="true"
        embed-xml="true"
    >
        <meta attribute="field-description">
           @hibernate.many-to-one
            not-null="true"
           @hibernate.column name="CREATE_EVENT_ID"         
        </meta>
        <column name="CREATE_EVENT_ID" />
    </many-to-one>

</class>
</hibernate-mapping>

from TaskEvent.hbm:

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>
<!-- 
    Created by the Middlegen Hibernate plugin 2.1

    http://boss.bekk.no/boss/middlegen/
    http://www.hibernate.org/
-->

<class 
    name="com.blah.TaskEvent" 
    table="TASK_EVENT"
>
    <meta attribute="class-description" inherit="false">
       @hibernate.class
        table="TASK_EVENT"
    </meta>

    <id
        name="eventId"
        type="java.math.BigDecimal"
        column="EVENT_ID"
    >
        <meta attribute="field-description">
           @hibernate.id
            generator-class="assigned"
            type="java.math.BigDecimal"
            column="EVENT_ID"

        </meta>
        <generator class="assigned" />
    </id>

    <property
        name="eventTimestamp"
        type="java.sql.Timestamp"
        column="EVENT_TIMESTAMP"
        length="23"
    >
        <meta attribute="field-description">
           @hibernate.property
            column="EVENT_TIMESTAMP"
            length="23"
        </meta>    
    </property>

    <!-- Associations -->

</class>
</hibernate-mapping>

donall05 · **Joined:** Mon May 09, 2005 7:57 am **Posts:** 5

re: my earlier post, i notice that the POJOs generated from the data are correct, in that the TaskItem POJO has methods called
getTaskEventByCreateEventId()
and
getTaskEventByLastEventId()

so is this a problem with the XML generator?

matthijsln · **Joined:** Tue Oct 18, 2005 9:51 am **Posts:** 4

I also have this problem and it still occurs using 3.1rc2.

<many-to-one
name="fk1"
class="FKClass"
column="FK1_ID"
fetch="join"
embed-xml="true"
/>

<many-to-one
name="fk2"
class="FKClass"
column="FK2_ID"
fetch="join"
embed-xml="true"
/>

this generates two "fk1" elements instead of a "fk1" and a "fk2" element.

pksiv · **Posted:** Tue Oct 18, 2005 11:20 am

donall05 wrote:

so is this a problem with the XML generator?

I believe it is a problem with the XML Generator because all objects are of org.dom4j.Element.

I haven't noticed a lot of development on this part in a while but one way I got it to work is to create a second mapping for the associated Class using a different entity-name and specifying that as the entity-name on the many-to-one.

Code:

<class name="FKClass" entity-name="TaskEventByCreateEvent" table="xxx">
...
</class>

<class entity-name="TaskEventByLastEvent" table="xxx" mutable="false">
...
</class>



<many-to-one name="fk1" class="FKClass" column="FK1_ID" fetch="join" embed-xml="true" entity-name="TaskEventByCreateEvent"/>

<many-to-one name="fk2" class="FKClass" column="FK2_ID" fetch="join" embed-xml="true" entity-name="TaskEventByLastEvent"/>

matthijsln · **Joined:** Tue Oct 18, 2005 9:51 am **Posts:** 4

Unfortunately this problem seems to be more entrenched and can't always be solved with that workaround; for example this is the next problem I'm having with Hibernate and XML:

(shortened mapping)

Code:

<class name="Organisation">
  ...
  <many-to-one name="projectLeader" class="Employee" embed-xml="true"/>

  <set name="permits" embed-xml="true">
    <key column="organisation_id"/>
    <one-to-many class="Permit" embed-xml="true"/>
  </set>
</class>

<class name="Employee">
  ... (at least one property besides ID)
</class>

<class name="Permit">
  ...
  <many-to-one name="approver" class="Employee" embed-xml="true"/>
</class>

This generates:

Code:

<Organisation>
  ...
  <projectLeader>
    ...
  </projectLeader>

  <permits>
     <Permit>
       ...
       <projectLeader> <!-- SHOULD BE "approver" -->
         ...
       </projectLeader>
     </Permit>
  </permits>
</Organisation>

Seems like something goes seriously wrong when looking up the element name. Even if I add node="approver" to the many-to-one in Permit the element name in Organisation/permits/Permit will still be the incorrect "projectLeader".

pksiv · **Posted:** Tue Oct 18, 2005 1:02 pm

My workaround suggest changing your mapping file like this. And it does work. I use it extensively.

Code:

<class name="Organisation">
  ...
  <many-to-one name="projectLeader" class="Employee" embed-xml="true" entity-name="ProjectLeader"/>

  <set name="permits" embed-xml="true">
    <key column="organisation_id"/>
    <one-to-many class="Permit" embed-xml="true"/>
  </set>
</class>

<class name="Employee" entity-name="ProjectLeader">
  ... (at least one property besides ID)
</class>

<class entity-name="Approver" table="Employee">
  ... (at least one property besides ID)
</class>


<class name="Permit">
  ...
  <many-to-one name="approver" class="Employee" embed-xml="true" entity-name="Approver"/>
</class>

matthijsln · **Joined:** Tue Oct 18, 2005 9:51 am **Posts:** 4

These workarounds do indeed work, but for my situation the cure is worse than the disease:

I have to map the same table over and over again for every association as an entity with the name I want to give my association as the entity-name(!). This is not feasible for the size of my model (I'll end up with my POJO's drowned in the redundant entities for all assocations). This workaround also breaks my build system using hbm2java which apparently can't handle POJO's and XML entitites simultaneously.

Will this bug be fixed or do I have to switch to Castor?

max · **Posted:** Wed Oct 19, 2005 9:16 am

suggestions to how hbm2java could ever handle you mapping the same class twice is welcome ;)

pksiv · **Posted:** Wed Oct 19, 2005 9:20 am

max wrote:

suggestions to how pojo could ever handle you mapping the same class twice is welcome ;)

Max,

This works without issue in the POJO world. The issue arises only when exporting XML. See JIRA issue HHH-794

max · **Posted:** Wed Oct 19, 2005 9:25 am

My comment where a reply/question on:

Quote:

hbm2java which apparently can't handle POJO's and XML entitites simultaneously

not regarding the xml export stuff which there already is a jira issue for (as I understand it)[/quote]

matthijsln · **Joined:** Tue Oct 18, 2005 9:51 am **Posts:** 4

max wrote:

suggestions to how hbm2java could ever handle you mapping the same class twice is welcome ;)

The workaround is mapping the table multiple times, not the class.

I got an error from hbm2java when I implemented the workaround but didn't investigate further as to how I might solve it - I've switched to Castor in the meantime until HHH-794 is fixed.

In case you're interested the exception was:

Code:

org.hibernate.tool.hbm2x.ExporterException: Error while processing template pojo/javaclass.vm
        at org.hibernate.tool.hbm2x.TemplateHelper.processTemplate(TemplateHelper.java:89)
...
Caused by: org.apache.velocity.exception.MethodInvocationException: Invocation of method 'getPackageDeclaration' in  class org.hibernate.tool.hbm2x.Cfg2JavaTool threw exception class java.lang.NullPointerException : null
        at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:246)
        at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:175)
        at org.apache.velocity.runtime.parser.node.ASTReference.render(ASTReference.java:220)
        at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:230)
        at org.apache.velocity.Template.merge(Template.java:256)
        at org.apache.velocity.app.VelocityEngine.mergeTemplate(VelocityEngine.java:450)
        at org.apache.velocity.app.VelocityEngine.mergeTemplate(VelocityEngine.java:419)
        at org.hibernate.tool.hbm2x.TemplateHelper.processTemplate(TemplateHelper.java:81)
        ... 17 more

max · **Posted:** Wed Oct 19, 2005 10:26 am

hmm - so this is for an mapped entity without a class ?

could you put it in jira so i wont forget it (at least report some meaningfull message ;)

pksiv · **Posted:** Wed Oct 19, 2005 10:31 am

max wrote:

hmm - so this is for an mapped entity without a class ?

could you put it in jira so i wont forget it (at least report some meaningfull message ;)

Max,

I put this in JIRA (HHH-794) a while ago complete with a runable example.

The problem exists whether or not there is a class associated with the mapping, but only when generating the XML. I assume it has something to do with the fact that when generating the XML, all objects are of the same class, org.dom4j.Element.

By assigning a separate entity-name it still works for the POJO using the class specified in the POJO.

max · **Posted:** Wed Oct 19, 2005 10:34 am

HHH-794 is still about the bug in the core, i am talking about the issue with hbm2java which is just related and i cant see described in hhh-794