[basex-talk] Problem with XQJ-Implementation (method XQResultSequence.getSequenceAsStream)

3 Apr 2012

      Hi

I am experiencing the BaseX API XQJ and I compare to other XQJ NXD and I 
find the following problem.

Suppose we have the next XML file in database "test":

<?xml version="1.0" encoding="ISO-8859-1"?>
<bookstore param="hao">
<book>
<title>Book01</title>
</book>
<book>
<title>Book02</title>
</book>
</bookstore>

If I execute:

     XQDataSource xqs = ...
     XQConnection conn = xqs.getConnection();
     XQExpression xqe = conn.createExpression();
     String cad= "collection('test')//title";

     XQResultSequence xqrs = xqe.executeQuery(cad);
     XMLStreamReader result = xqrs.getSequenceAsStream();
     System.out.println("Iteration on XMLStreamReader...");
     for(; result.hasNext(); result.next())
       System.out.println(getEventString(result));

     xqrs = xqe.executeQuery(cad);
     System.out.println("Using a Transformer...");
     Source resultXML = new StAXSource(xqrs.getSequenceAsStream());
     StreamResult resultSR = new StreamResult(System.out);
     TransformerFactory factory = TransformerFactory.newInstance();
     Transformer tr = factory.newTransformer();
     tr.setOutputProperty(OutputKeys.INDENT, "yes");
     tr.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "no");
     tr.setOutputProperty("{http://xml.apache.org/xslt}indent-amount","2");
     tr.transform(resultXML, resultSR);

where
   static String getEventString(final XMLStreamReader reader) {
     switch(reader.getEventType()) {
       case XMLStreamConstants.START_ELEMENT:
         return "START_ELEMENT:\t\"" + reader.getLocalName() + "\"";
       case XMLStreamConstants.END_ELEMENT:
         return "END_ELEMENT:\t\"" + reader.getLocalName() + "\"";
       case XMLStreamConstants.START_DOCUMENT:
         return "START_DOCUMENT";
       case XMLStreamConstants.END_DOCUMENT:
         return "END_DOCUMENT";
       case XMLStreamConstants.CHARACTERS:
         return "CHARACTERS:\t\"" + reader.getText() + "\"";
     }
     return "";
   }

I get:

     Iteration on XMLStreamReader...
     START_ELEMENT:  "title"
     CHARACTERS:     "Book01"
     END_ELEMENT:    "title"
     END_DOCUMENT
     START_ELEMENT:  "title"
     CHARACTERS:     "Book02"
     END_ELEMENT:    "title"
     END_DOCUMENT
     Using a Transformer...
     <?xml version="1.0" encoding="UTF-8"?>
     <title>Book01</title>

It's not good!

When I use a Transformer I should get something similar to:
     <?xml version="1.0" encoding="UTF-8"?>
     <result>
       <title>Book01</title>
       <title>Book02</title>
     <result>

That is, if result sequence length is greater than 1, getSequenceAsStream should wrap the sequence in a containing result element, so to not break JAXP Transformers and XMLStreamReader events.

Is there any solution in BaseX ?

Thanks a lot!

Isidre Guixà