[WICKET-2045] FileUploadField.onDetach() causes IllegalStateException()

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.4-RC1
• Fix Version/s: 1.4-RC2
• Component/s: wicket
• Environment: Linux ubuntu 2.6.24-23-generic #1 SMP Thu Nov 27 18:13:46 UTC 2008 x86_64 GNU/Linux; java version "1.6.0_07"; Java(TM) SE Runtime Environment (build 1.6.0_07-b06); Java HotSpot(TM) 64-Bit Server VM (build 10.0-b23, mixed mode)
• Assignee: Juegen Donnerstag
• Reporter: Andy Thomson
• Created: 25/Jan/09 00:43
• Updated: 25/Jan/09 11:40
• Resolved: 25/Jan/09 11:40

Description

This was detected when using the example/sample Upload demo locally.

ERROR - RequestCycle - there was an error cleaning up target org.apache.wicket.request.target.component.listener.ListenerInterfaceRequestTarget@20665159[Page class = org.apache.wicket.examples.upload.UploadPage, id = 0, version = 0]>simpleUpload->interface org.apache.wicket.markup.html.form.IFormSubmitListener.IFormSubmitListener (request paramaters: [RequestParameters componentPath=0:simpleUpload pageMapName=null versionNumber=0 interfaceName=IFormSubmitListener componentId=null behaviorId=null urlDepth=-1 parameters={} onlyProcessIfPathActive=false]).
java.lang.IllegalStateException: Attempt to set model object on null model of component: simpleUpload:fileInput
at org.apache.wicket.Component.setDefaultModelObject(Component.java:2962)
at org.apache.wicket.markup.html.form.FormComponent.setModelObject(FormComponent.java:1652)
at org.apache.wicket.markup.html.form.upload.FileUploadField.onDetach(FileUploadField.java:175)

Looking at the source indicates that unless onDetach() is over-ridden the default will always generate this exception. Here is the source for the FileUpLoadField.onDetach(). The line that creates the exception is noted by the "<<<HERE" in the snippet below.

FileUpLoadField.onDetach() snippet:

/**

• Clean up at the end of the request. This means closing all inputstreams which might have been
• opened from the fileUpload.
• @see org.apache.wicket.Component#onDetach()
  */
  @Override
  protected void onDetach()
  Unknown macro: { if (fileUpload != null && forceCloseStreamsOnDetach()) { fileUpload.closeStreams(); fileUpload = null; setModelObject(null); <<<HERE } super.onDetach(); }

Drilling further down, the setModelObject() calls FormComponent.setModelObject(), which in turns calls Component.setDefaultModelObject(). Inside setDefaultModelObject(), a check is done to see if the model object is null, if it is, it throws an exception:

public final Component setDefaultModelObject(final Object object)
{
final IModel<Object> model = (IModel<Object>)getDefaultModel();

// Check whether anything can be set at all
if (model == null)

{ throw new IllegalStateException( "Attempt to set model object on null model of component: " + getPageRelativePath()); }

...
}