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wSam
 Post subject: one-to-many relationship throws NullPointer
PostPosted: Fri Jun 23, 2006 8:43 am 
Beginner
Beginner

Joined: Fri Jun 23, 2006 6:28 am
Posts: 22
Hi

I have a table "ReportTables" which containst several "ReportFields". "ReportFields" is also a table, which contains two primary keys: a pk called "FIELD_NAME" and one called "REPORT_TABLES_ID". Both together gives a unique tuple.

The hibernate mapping looks like this:

Table ReportField:

Code:
<hibernate-mapping package="gugus">

  <class name="ReportField" table="REPORT_FIELDS" dynamic-update="true" dynamic-insert="true">
   
    <id name="fieldName" column="FIELD_NAME">
      <generator class="assigned"/>
    </id>
   
    <property name="fieldDesc" column="FIELD_DESC"/>
   
    <many-to-one name="reportTable" class="ReportTable" column="REPORT_TABLES_ID"/>

  </class>
</hibernate-mapping>


Mapping for ReportTable:


Code:
<hibernate-mapping package="gugus">

  <class name="ReportTable" table="REPORT_TABLES" dynamic-update="true" dynamic-insert="true">
 
    <id name="id" type="long" column="REPORT_TABLES_ID">
      <generator class="assigned"/>
    </id>

    <property name="tableName" column="TABLE_NAME"/>
   
    <set name="reportFields" table="REPORT_FIELDS" cascade="all" inverse="true">
      <key column="REPORT_TABLES_ID"/>
      <one-to-many class="ReportField"/>
    </set>

  </class>
</hibernate-mapping>



But now, when I change a ReportField, I recieve a NullPointerException:



Code:
java.lang.NullPointerException
            at weblogic.jdbc.wrapper.Statement.cancel(Statement.java:426)
            at net.sf.hibernate.impl.BatcherImpl.cancelLastQuery(BatcherImpl.java:279)
            at net.sf.hibernate.impl.SessionImpl.cancelQuery(SessionImpl.java:3772)
            at gugus.ReportFieldEditAction.doExecute(ReportFieldEditAction.java:64)
            at gugus.WebAction.execute(WebAction.java:114)
            at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:484)
            at gugus.TilesRequestProcessor.process(TilesRequestProcessor.java:193)
            at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
            at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
            at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
            at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
            at weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run(ServletStubImpl.java:1006)
            at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:419)
            at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:28)
            at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:27)
            at gugus.hibernate.filter.HibernateFilter.doFilter(HibernateFilter.java:54)

            at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:27)
            at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:6726)
            at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
            at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:121)
            at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:3766)
            at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2644)
            at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:219)
            at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:178)


I think, this is because when I only edit a ReportField (as an example, when I change only the "fieldDesc"), then it finds already one in the database.

This is, how I handle the update of my Object:


Code:
enableTransactionSupport();
    Session session = getHibernateSession();
   
    ReportField editReportField =  new ReportField();
    ReportTable parentTable = null;
   
    try {
      ServerAdminSessionObjects sObjects = (ServerAdminSessionObjects)
                    params.getSessionAttribute(Constants.SESSIONOBJECTS);
      editReportField = sObjects.getReportFieldToEdit();
      String fieldName = editReportField.getFieldName();
     
      parentTable = editReportField.getReportTable();
     
      WebForm webForm = (WebForm) params.getWebForm();
      webForm.updateBean(editReportField);
     
      Criteria searchCrit = session.createCriteria(ReportField.class);
      List list = searchCrit.add(Expression.like(FIELD_NAME, editReportField.getFieldName())).list();
      if ((list.size() > 0) && (fieldName.equals(((ReportField) list.get(0)).getFieldName()))) {
        ActionErrors retVal = new ActionErrors();
        retVal.add(FIELD_NAME, new ActionMessage("error.reportfield.edit"));
        this.setActionForward(params, params.findForward(ACTION_EDIT_FIELD));
      }
      parentTable.updateReportField(editReportField);
    }
    finally {
      try {
        if (parentTable != null) {
          session.update(parentTable);
        }
      }
      catch (HibernateException e) {
        session.cancelQuery();
        e.printStackTrace();
      }
    }



How can I solve this problem?


Thanks in advance and greets
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neketsushonen
 Post subject: What line is the number 64
PostPosted: Fri Jun 23, 2006 10:08 am 
Regular
Regular

Joined: Wed Feb 22, 2006 11:28 am
Posts: 65
Location: Santiago, Chile
Hello Friend:

after reading your problem... and saw your expcetion trace, I want to ask you, what is the line:

"ReportFieldEditAction.java:64".

Can you tell me, then i can help you.

_________________
If you called Wisdom, please help to all to solve theirs problems.

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wSam
 Post subject:
PostPosted: Sat Jun 24, 2006 4:36 pm 
Beginner
Beginner

Joined: Fri Jun 23, 2006 6:28 am
Posts: 22
Hi

Quote:
after reading your problem... and saw your expcetion trace, I want to ask you, what is the line:

"ReportFieldEditAction.java:64".

Can you tell me, then i can help you.


This Class contains this Code:

Code:
enableTransactionSupport();
    Session session = getHibernateSession();
   
    ReportField editReportField =  new ReportField();
    ReportTable parentTable = null;
   
    try {
      ServerAdminSessionObjects sObjects = (ServerAdminSessionObjects)
                    params.getSessionAttribute(Constants.SESSIONOBJECTS);
      editReportField = sObjects.getReportFieldToEdit();
      String fieldName = editReportField.getFieldName();
     
      parentTable = editReportField.getReportTable();
     
      WebForm webForm = (WebForm) params.getWebForm();
      webForm.updateBean(editReportField);
     
      Criteria searchCrit = session.createCriteria(ReportField.class);
      List list = searchCrit.add(Expression.like(FIELD_NAME, editReportField.getFieldName())).list();
      if ((list.size() > 0) && (fieldName.equals(((ReportField) list.get(0)).getFieldName()))) {
        ActionErrors retVal = new ActionErrors();
        retVal.add(FIELD_NAME, new ActionMessage("error.reportfield.edit"));
        this.setActionForward(params, params.findForward(ACTION_EDIT_FIELD));
      }
      parentTable.updateReportField(editReportField);
    }
    finally {
      try {
        if (parentTable != null) {
          session.update(parentTable);
        }
      }
      catch (HibernateException e) {
        session.cancelQuery();
        e.printStackTrace();
      }
    }


When I debugged the code, it throws here:
Code:
session.update(parentTable);


So it is because there is already a tuple with the same fieldname in the database. I think it is rather a mapping problem, because I dont know how to create a mapping for a table with two primary keys.

greets
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scarface
 Post subject:
PostPosted: Sat Jun 24, 2006 5:04 pm 
Senior
Senior

Joined: Sun Jun 04, 2006 1:58 am
Posts: 136
http://www.hibernate.org/hib_docs/reference/en/html/mapping.html#mapping-declaration-compositeid

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wSam
 Post subject:
PostPosted: Wed Jun 28, 2006 7:13 am 
Beginner
Beginner

Joined: Fri Jun 23, 2006 6:28 am
Posts: 22
@scarface

Your hint with the composite-id worked. Thanks.

I made it like this:

Code:
<composite-id>
   <key-property name="fieldName" column="FIELD_NAME"/>
   <key-many-to-one name="reportTable" class="ReportTable" column="REPORT_TABLES_ID"/>
</composite-id>


But so It dont update the "fieldName" attribute:

Code:
update
  REPORT_FIELDS
set
  FIELD_DESC=?,
where
  FIELD_NAME=? and REPORT_TABLES_ID=?


It sets only the property field "fieldDesc". How can I make, that it also updates the propertys from the composite-id?

greets
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scarface
 Post subject:
PostPosted: Wed Jun 28, 2006 7:29 pm 
Senior
Senior

Joined: Sun Jun 04, 2006 1:58 am
Posts: 136
take off

dynamic-update="true"

from the top of of the mapping file you will see all the feilds

not fieldName because that's in the where clause !!

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