drag n drop sometimes produces: Argument Error: Parameter te

[badjan]

Hi,

I'm using drag and drop feature to add/move Images from one place to another. Everything works fine, but sometimes this error occurs when dragging / dropping an image from "availableImagesListScrollerGrid" to "usedImageDropArea":

12.08.2009 12:24:42 com.sun.facelets.FaceletViewHandler handleRenderException
SCHWERWIEGEND: Error Rendering View[/WEB-INF/flow/story/editStory.xhtml]
java.lang.NullPointerException: Argument Error: Parameter text is null
 at com.sun.faces.renderkit.html_basic.HtmlResponseWriter.writeText(HtmlResponseWriter.java:826)
 at org.richfaces.renderkit.DnDParametersEncoder.doEncodeAsMap(DnDParametersEncoder.java:228)
 at org.richfaces.renderkit.DnDParametersEncoder.doEncodeAsString(DnDParametersEncoder.java:130)
 at org.richfaces.renderkit.html.DragSupportRenderer.encodeEnd(DragSupportRenderer.java:95)
 at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:861)
 at org.ajax4jsf.renderkit.RendererBase.renderChild(RendererBase.java:281)

....

at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
 at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
 at java.lang.Thread.run(Unknown Source)

XHTML Code:

<rich:tab label="Bildergalerie">
 <rich:panel>
 <f:facet name="header">
 <h:outputText value="Bildergalerie für diese Seite" />
 </f:facet>

 <rich:panel>
 <f:facet name="header">
 <h:outputText value="Bilder die für diese Seite angezeigt werden sollen" />
 </f:facet>
 <rich:dropSupport id="usedImageDropArea"
 acceptedTypes="imageAvail"
 dropListener="#{StoryBB.processAddImageForGallery}"
 reRender="usedImagesListScrollerGrid, availableImagesListScrollerGrid"
 immediate="true"/>
 <rich:dataGrid id="usedImagesListScrollerGrid" value="#{actSoStory.soImages}"
 var="usedImage"
 columns="5"
 elements="10"
 styleClass="top">

 <a4j:outputPanel layout="block">
 <rich:dragSupport dragIndicator=":indicator"
 dragValue="#{usedImage}"
 dragType="removeImage">
 <rich:dndParam name="label" value="#{usedImage.imageName}" />
 <rich:panel>
 <f:facet name="header">
 <h:outputText value="#{usedImage.imageName}" style="font-size: 7pt;" />
 </f:facet>
 <h:graphicImage width="140px;" value="#{pathValues.imagePath}#{usedImage.imagePath}#{usedImage.imageSmall}"/>
 </rich:panel>
 </rich:dragSupport>
 </a4j:outputPanel>
 <f:facet name="footer">
 <rich:datascroller for="usedImagesListScrollerGrid" maxPages="10" pageIndexVar="pageIndex" pagesVar="pages" immediate="true"
 limitToList="true"
reRender="usedImagesListScrollerGrid"/>
 </f:facet>
 </rich:dataGrid>
 </rich:panel>

 <f:verbatim>
 <p>
 Bilder per Drag und Drop von <b>unten nach oben ziehen</b>, um sie der Bildergalerie für diesen Text hinzuzufügen.<br/>
 Um Bilder wieder aus der Galerie zu entfernen einfach von wieder zurück von <b>oben nach unten ziehen</b>.
 </p>
 </f:verbatim>

 <rich:panel>
 <f:facet name="header">
 <h:outputText value="Verfügbare Bilder" />
 </f:facet>
 <rich:dropSupport id="availImagesDropArea"
 acceptedTypes="removeImage"
 dropListener="#{StoryBB.processRemoveImageForGallery}"
 reRender="availableImagesListScrollerGrid, usedImagesListScrollerGrid" immediate="true">
 <rich:dataGrid id="availableImagesListScrollerGrid" value="#{AvailableSoImageExtendedDataModel}"
 var="avImage"
 columns="5"
 elements="10"
 styleClass="top" >
 <f:facet name="header">
 <rich:datascroller for="availableImagesListScrollerGrid" maxPages="15" pageIndexVar="pageIndex" pagesVar="pages"
immediate="true" limitToList="true" reRender="availableImagesListScrollerGrid"/>
 </f:facet>

 <a4j:outputPanel layout="block">
 <rich:dragSupport dragIndicator=":indicator"
 dragValue="#{avImage}"
 dragType="imageAvail"
 rendered="#{!snow:inSoImages(actSoStory.soImages,avImage)}">
 <rich:dndParam name="label" value="#{avImage.imageName}" />
 <rich:panel>
 <f:facet name="header">
 <h:outputText value="#{avImage.imageName}" style="font-size: 7pt;" />
 </f:facet>
 <h:graphicImage width="140px;" value="#{pathValues.imagePath}#{avImage.imagePath}#{avImage.imageSmall}"/>
 </rich:panel>
 </rich:dragSupport>
 </a4j:outputPanel>
 </rich:dataGrid>
 </rich:dropSupport>
 </rich:panel>

 </rich:panel>
 </rich:tab>

I just don't know why this error happens und I can't find the component which produces it. Is it made by dropSupport, dragSupport, dndParam or even a4j:outputPanel or something I didn't think of??

The error is about a NullpointerException, but no matter which value/object I think of - everything is filled with data. So there is no text/string attribute which could be null. ...as far as I can think of ;)

I'm using: RichFaces richfaces 3.3.2-20090731

Please help me out of this :)

Jan