Re: [Exist-open] cannot import result in existing document

[Guy De S. <mai...@de...>]

----- Original Message -----
From: "Guy De Schepper" <mai...@de...>
To: <exi...@li...>
Sent: Monday, December 02, 2002 21:12
Subject: [Exist-open] cannot import result in existing document


> I have problems importing the result of a query in an xml Document object.
>
> I'm using the xmldb api, and try to do the following:
>
>
> // Query the database:
>
>   public synchronized Document queryDocument(String p_collection, String
> p_xpath) {
>     Collection col = null;
>     XPathQueryService service = null;
>     Document doc = null;
>
>     try {
>       if (EXIST) {
>         // for eXist, add an extra * at the end of the query
>         p_xpath += "*";
>       }
>       col = getCollection(p_collection);
>       System.out.println("col = " + col);
>       service = (XPathQueryService) col.getService("XPathQueryService",
> XMLDBAPIVERSION);
>       System.out.println("p_xpath = " + p_xpath);
>       ResourceSet resultSet = service.query(p_xpath);
>       doc = combineXPathResults(resultSet);
>     }
>     catch (XMLDBException exc) {
>       System.err.println("error requesting data from database");
>       exc.printStackTrace();
>     }
>
>     return doc;
>   }
>
>
> // Everything still works fine
>
> // combine all results in one document
>   public Document combineXPathResults(ResourceSet result) throws
> XMLDBException {
>     // Create a new Document and a root element that will
>     // have all the results as its children
>     Document resultDoc = null;
>     Element root = null;
>
>     resultDoc = new DocumentImpl();
>
>     // Iterate the xpath results and add each of them to the main Document
>     ResourceIterator iterator = result.getIterator();
>     if (iterator.hasMoreResources()) {
>       root = resultDoc.createElement(XMLRESULT_TOP_ELEMENT);
>       resultDoc.appendChild(root);
>       System.out.println("docelem = " +
> resultDoc.getDocumentElement().getNodeName());  // this displays: docelem
=
> result
>       while(iterator.hasMoreResources()) {
>         Resource r = iterator.nextResource();
>         Element resElement;
>         Node mynode = null;
>         if (EXIST) {
>           System.out.println("resource = " + r);  // output: resource =
> org.exist.xmldb.LocalXMLResource@4bfe9d
>           System.out.println("resourcetype = " + r.getResourceType());  //
> output: resourcetype = XMLResource
>           mynode = ((XMLResource)r).getContentAsDOM();
>           System.out.println("mynode = " + mynode.getNodeName());  //
> output: mynode = configuration
>           resElement = (Element) mynode;
>           System.out.println("resElement = " + resElement.getNodeName());
> // output: resElement = configuration
>         }
>         else {
>           resElement = ((Document)
> ((XMLResource)r).getContentAsDOM()).getDocumentElement();
>         }
>
>         // Remove unwanted attributes (for XIndice)
>         resElement.removeAttribute("src:col");
>         resElement.removeAttribute("src:key");
>         resElement.removeAttribute("xmlns:src");
>
>         System.out.println("resElement = " + resElement.getNodeName());
//
> output: resElement = configuration
>         System.out.println("docelem = " +
> resultDoc.getDocumentElement().getNodeName());  // output: docelem =
result
>         // Add this result to the root element
>         Element importedElement =
(Element)resultDoc.importNode(resElement,
> true);
>
> // here I get an exception:
> Exception in thread "main" java.lang.NullPointerException
>         at
>
org.apache.xerces.dom.CoreDocumentImpl.importNode(CoreDocumentImpl.java:899)
>         at
>
org.apache.xerces.dom.CoreDocumentImpl.importNode(CoreDocumentImpl.java:862)
>         at
> be.securit.dman.XmlDbAdapter.combineXPathResults(XmlDbAdapter.java:252)
>         at
be.securit.dman.XmlDbAdapter.queryDocument(XmlDbAdapter.java:200)
>         at be.securit.dman.DataManager.populate(DataManager.java:254)
>         at be.securit.dman.DataManager.init(DataManager.java:226)
>         at be.securit.dman.DataManager.main(DataManager.java:215)
> //
>
>         root.appendChild(importedElement);
>       }
>
>
>     }
>
>     return resultDoc;
>   }
>
>
> When I run the same code with XIndice, I don't have this problem.
>
>
> Any ideas what could be wrong ?
>
>
> /* Guy */
>
>
>
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When I try to cast the result to a Document element (as I do with XIndice):
        Document mydoc = (Document) ((XMLResource)r).getContentAsDOM();
I get following exception:
Exception in thread "main" java.lang.ClassCastException:
org.exist.dom.ElementImpl
        at
be.securit.dman.XmlDbAdapter.combineXPathResults(XmlDbAdapter.java:239)
        at be.securit.dman.XmlDbAdapter.queryDocument(XmlDbAdapter.java:200)
        at be.securit.dman.DataManager.populate(DataManager.java:254)
        at be.securit.dman.DataManager.init(DataManager.java:226)
        at be.securit.dman.DataManager.main(DataManager.java:215)


This indicates exist uses its own ElementImpl Object. How can I convert it
to an org.w3c.dom.ElementImpl Object ?
Or maybe there are other possibilities to import this Node into an existing
Document (org.w3c.dom.DocumentImpl) Object ?

/* Guy */