Transformer: DocumentFragment and SAX events

[Alessandro Vincelli <a....@w4b.it>]

Hi all,

I am trying to write a custom Transformer which should do the following:

ignore everything except <row> elements;
when an <row> element is encountered, generate a <tr> element, 
containing a <td> element for every child of the source <row> element;

example:

source:

...<anything>...
<row>
    <field1>A</field1>
    <field2>B</field2>
</row>
...</anything>...

should produce:

<tr>
    <td>A</td>
    <td>B</td>
</tr>




My approach is, when I find a <row> element, to use startRecording(), 
with endRecording() when the end of the <row> element is reached. Thus I 
get a DocumentFragment from which I can extract what I need.

The problem is that the resulting DocumentFragment gets populated with 
the nodes I need *only if I call super.startElement() for every 
element*. But, this way, I get in the result also elements I wish to 
suppress.

Example:

...<anything>...
<row>
    <field1>A</field1>
    <field2>B</field2>
</row>
...</anything>...

actually produces:

...<anything>...
<tr>
    <td>A</td>
    <td>B</td>
</tr>
...</anything>...

How can I overcome this? I am sure that I am doing something deeply 
wrong, as you can see from the attached source.

Thanks in advance,

Alessandro


package com.w4b.formProcessor;

import org.apache.cocoon.transformation.*;
import org.w3c.dom.DocumentFragment;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.Attributes;
import org.xml.sax.helpers.AttributesImpl;
import org.xml.sax.SAXException;

import org.apache.cocoon.transformation.AbstractTransformer;
import org.apache.cocoon.environment.SourceResolver;
import org.apache.cocoon.ProcessingException;
import org.apache.avalon.framework.parameters.Parameters;
import org.xml.sax.SAXException;
import java.util.Map;


public class ExcelOutputTransformer extends AbstractSAXTransformer

{
    boolean firstRow;
    AttributesImpl attrs = new AttributesImpl();
   
    public void startDocument() throws SAXException{
        firstRow = true;
        getLogger().debug("inizio documento...");
        super.startElement("","table","table",attrs);
    }
    public void endDocument() throws SAXException{
        getLogger().debug("fine documento.");
        super.endElement("","table","table");
    }
    public void startElement(String nsURI, String localName, String 
qualName, Attributes attr) throws SAXException{
       
        getLogger().debug(localName);
       
        if (!(localName.equals("row"))) {
            
super.contentHandler.startElement(nsURI,localName,qualName,attr);
            return;
        }
        getLogger().debug("inizio riga...");
        this.startRecording();
       
       
    }
    public void endElement(String nsURI, String localName, String 
qualName) throws SAXException{
       
        if (!(localName.equals("row"))) {
            super.contentHandler.endElement(nsURI,localName,qualName);
            return;
        }
               
        getLogger().debug("fine riga.");

       
        DocumentFragment df = this.endRecording();
       


        if (firstRow) {
            super.startElement("","tr","tr",attrs);
           
            Node n = df.getFirstChild();
            int i = 0;
           
            while (n!=null)  {
                i++;
               
                if (n!=null) {
                    super.startElement("","td","td",attrs);
                    String val = n.getNodeName();
                    super.characters(val.toCharArray(),0,val.length());
                    super.endElement("","td","td");
                } else {
                    getLogger().debug("nodo " + i + "nullo.");
                }
                n = n.getNextSibling();
            }
            super.endElement("","tr","tr");
            firstRow = false;
        }
       
        Node n = df.getFirstChild();
        int i = 0;
        super.startElement("","tr","tr",attrs);
        while (n!=null)  {
            i++;
            if (n.getFirstChild()!=null) {
                super.startElement("","td","td",attrs);
                String val = n.getFirstChild().getNodeValue();
                super.characters(val.toCharArray(),0,val.length());
                super.endElement("","td","td");

            }    else {
                getLogger().debug("nodo " + i + "nullo.");
            }
            n = n.getNextSibling();
        }
        super.endElement("","tr","tr");
       
    }
}





-- 
-------------------------------
Alessandro Vincelli 
W4B - web for business s.r.l.
Firenze 
via Pellicceria 10 - 50123
E-mail: a.vincelli@w4b.it
tel: 055-2654270 


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