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Re: Weird NullPointerException
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Re: Weird NullPointerException

  • Subject: Re: Weird NullPointerException
  • From: Markus Ruggiero <email@hidden>
  • Date: Mon, 28 Mar 2011 22:59:35 +0200
Thanks Chuck, you made my day.

Cheers
---markus---

On 25.03.2011, at 18:47, Chuck Hill wrote:

Hi Markus,


On Mar 25, 2011, at 3:41 AM, Markus Ruggiero wrote:

I have an EO that has business logic for creating an PDF file. There is a WOComponent that generates an XML which is then fed to ApacheFOP. Following code is in the EO:

GeneratedDocument.java

public void generatePDF(WOComponent sender) {
if (sender == null) {
return;
}

String generatorName = xmlGeneratorClassName();
if (generatorName != null) {
XmlGeneratorComponent xmlGenerator = (XmlGeneratorComponent)sender.pageWithName(generatorName);

That might be a problem there.  Try this instead:
XmlGeneratorComponent xmlGenerator = (XmlGeneratorComponent)WOApplication.application().pageWithName(generatorName, new WOContent(sender.context().request()));

It is usually safer to create a new context for things like this.


Chuck


PDFGenerator pdfGenerator = PDFGenerator.sharedInstance();
pdfGenerator.generatePdfFile( this, xmlGenerator );
}
else {
log.error( "*** No xmlGeneratorClassName available" );
}
}


Depending on the context I call this I get a NullPointerException or not. This is the NPE, context info follows below:

Mar 25 11:13:49 ec_admin[13000] WARN  NSLog  - <com.webobjects.appserver._private.WOComponentRequestHandler>: Exception occurred while handling request:
java.lang.NullPointerException
[2011-3-25 11:13:49 CET] <WorkerThread14> java.lang.NullPointerException
at com.webobjects.appserver._private.WOComponentReference._popComponentFromContext(WOComponentReference.java:108)
at com.webobjects.appserver._private.WOComponentReference.invokeAction(WOComponentReference.java:128)
at er.extensions.components._private.ERXSwitchComponent.invokeAction(ERXSwitchComponent.java:117)
at com.webobjects.appserver._private.WODynamicGroup.invokeChildrenAction(WODynamicGroup.java:105)
at com.webobjects.appserver._private.WODynamicGroup.invokeAction(WODynamicGroup.java:115)
at er.extensions.components._private.ERXWORepetition.invokeAction(ERXWORepetition.java:496)
at com.webobjects.appserver._private.WODynamicGroup.invokeChildrenAction(WODynamicGroup.java:105)
at er.extensions.components.conditionals.ERXWOConditional.invokeChildrenAction(ERXWOConditional.java:113)
at com.webobjects.appserver._private.WODynamicGroup.invokeAction(WODynamicGroup.java:115)
at er.extensions.components.conditionals.ERXWOConditional.invokeAction(ERXWOConditional.java:104)
at com.webobjects.appserver.WOComponent.invokeAction(WOComponent.java:1079)
at com.webobjects.appserver._private.WOComponentReference.invokeAction(WOComponentReference.java:127)
at com.webobjects.appserver._private.WODynamicGroup.invokeChildrenAction(WODynamicGroup.java:105)
at com.webobjects.appserver._private.WODynamicGroup.invokeAction(WODynamicGroup.java:115)
at com.webobjects.appserver._private.WOComponentContent.invokeAction(WOComponentContent.java:38)
at com.webobjects.appserver._private.WODynamicGroup.invokeChildrenAction(WODynamicGroup.java:105)
at com.webobjects.appserver._private.WODynamicGroup.invokeAction(WODynamicGroup.java:115)
at com.webobjects.appserver.WOComponent.invokeAction(WOComponent.java:1079)
at com.webobjects.appserver._private.WOComponentReference.invokeAction(WOComponentReference.java:127)
at er.extensions.components._private.ERXSwitchComponent.invokeAction(ERXSwitchComponent.java:117)
at com.webobjects.appserver._private.WODynamicGroup.invokeChildrenAction(WODynamicGroup.java:105)
at com.webobjects.appserver._private.WODynamicGroup.invokeAction(WODynamicGroup.java:115)
at com.webobjects.appserver.WOComponent.invokeAction(WOComponent.java:1079)
at er.directtoweb.pages.ERD2WPage.invokeAction(ERD2WPage.java:619)
at er.directtoweb.pages.ERD2WListPage.invokeAction(ERD2WListPage.java:479)
at com.webobjects.appserver.WOSession.invokeAction(WOSession.java:1357)
at com.webobjects.appserver.WOApplication.invokeAction(WOApplication.java:1745)
at er.extensions.appserver.ajax.ERXAjaxApplication.invokeAction(ERXAjaxApplication.java:93)
at er.extensions.appserver.ERXApplication.invokeAction(ERXApplication.java:1863)
at com.webobjects.appserver._private.WOComponentRequestHandler._dispatchWithPreparedPage(WOComponentRequestHandler.java:206)
at com.webobjects.appserver._private.WOComponentRequestHandler._dispatchWithPreparedSession(WOComponentRequestHandler.java:298)
at com.webobjects.appserver._private.WOComponentRequestHandler._dispatchWithPreparedApplication(WOComponentRequestHandler.java:332)
at com.webobjects.appserver._private.WOComponentRequestHandler._handleRequest(WOComponentRequestHandler.java:369)
at com.webobjects.appserver._private.WOComponentRequestHandler.handleRequest(WOComponentRequestHandler.java:442)
at com.webobjects.appserver.WOApplication.dispatchRequest(WOApplication.java:1687)
at er.extensions.appserver.ERXApplication.dispatchRequestImmediately(ERXApplication.java:1978)
at er.extensions.appserver.ERXApplication.dispatchRequest(ERXApplication.java:1943)
at com.dsm.ec_admin.Application.dispatchRequest(Application.java:289)
at com.webobjects.appserver._private.WOWorkerThread.runOnce(WOWorkerThread.java:144)
at com.webobjects.appserver._private.WOWorkerThread.run(WOWorkerThread.java:226)
at java.lang.Thread.run(Thread.java:680)

In some D2WInspectPages I have a nextPageDelegate. Calling from here everything works.
This is the code in MyNextPageDelegate

public WOComponent nextPage(WOComponent sender) {

if (!(sender instanceof ERD2WInspectPage)) {
return null;
}

// make sure that we are in Edit mode:
String task = (String)((ERD2WInspectPage)sender).d2wContext().valueForKey( "task" );
if (! "edit".equals( task )) {
return null;
}

// trap cancel
if (!((ERD2WInspectPage)sender).objectWasSaved()) {
return null;
}

EOEnterpriseObject object = (EOEnterpriseObject)sender.valueForKey( "object" );

if (object instanceof GeneratedDocument) {
((GeneratedDocument)object).generatePDF( sender );
}
return null;
}

In a ListPage I have a belowPropertyKey. This is handled by a custom property level component showing a WOHyperlink. When I call the same business logic from the action method bound to the link the PDF is created but at the end I get above mentioned NPE.

public WOActionResults generateAll() {
   ERD2WListPage parentListPage = parentListPage();
        if (parentListPage != null) {
    WODisplayGroup displayGroup = parentListPage.displayGroup();
    NSArray<EOEnterpriseObject> objects = displayGroup.allObjects();
    generate(objects);
        }
      return parentListPage;
}


    /** Utility to return the enclosing list page, if there is one. */
    protected ERD2WListPage parentListPage() {
        return (ERD2WListPage)ERD2WUtilities.enclosingPageOfClass(this, ListPageInterface.class);
    }

    private void generate(NSArray<EOEnterpriseObject> objects) {

    for (EOEnterpriseObject object : objects) {
    if (object instanceof GeneratedDocument) {
    ((GeneratedDocument)object).generatePDF( parentListPage());
    }
     }
    }

I am sure I must be overlooking something but what? Any help insanely appreciated.
Thanks
---markus---



-- 
Chuck Hill             Senior Consultant / VP Development

Practical WebObjects - for developers who want to increase their overall knowledge of WebObjects or who are trying to solve specific problems.    
http://www.global-village.net/products/practical_webobjects








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References: 
 >Weird NullPointerException (From: Markus Ruggiero <email@hidden>)
 >Re: Weird NullPointerException (From: Chuck Hill <email@hidden>)

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