Problem with adding an XML node to an existent XML File

[Hugo Alberto Bedolla]

I got a problem when trying to write a new node to an xml file, basically the new node isn't appended to the file. I tried to write to another file, but in both cases, only the old data appears... what am I doing wrong? :S


Here's my code:

public void addXmlData(XmlData xmlData) throws XmlDataException {
        
        synchronized (this) {
            try {
                DocumentBuilderFactory dbfac = DocumentBuilderFactory.newInstance();
                DocumentBuilder docBuilder = dbfac.newDocumentBuilder();
                
                File file = new File("/home/myhome/an_xml_file.xml");
                
                Document doc = docBuilder.parse(file);
                
                XPath xpath = XPathFactory.newInstance().newXPath();
                
                String XmlDataName = xmlData.getXmlDataName();
                
                String search = "//XmlData[@name='" + XmlDataName + "']";
                
                XPathExpression expr = xpath.compile(search);
                
                Node result = (Node)expr.evaluate(doc, XPathConstants.NODE);
                
                if(result == null) {
                    Element XmlDataElement = doc.createElement("XmlData");
                    XmlDataElement.setAttribute("name", xmlData.getXmlDataName());
                    
                    Element descriptionElement = doc.createElement("XmlData-description");
                    descriptionElement.setTextXmlData(xmlData.getXmlDataDescription());
                    XmlDataElement.appendChild(descriptionElement);
                    
                    Element baseLocaleElement = doc.createElement("base-locale");
                    baseLocaleElement.setAttribute("locale", xmlData.getXmlDataLocale());
                    XmlDataElement.appendChild(baseLocaleElement);                    
                    
                    //set up a transformer
                    TransformerFactory transfac = TransformerFactory.newInstance();
                    Transformer trans = transfac.newTransformer();
                    trans.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
                    //trans.setOutputProperty(OutputKeys.INDENT, "yes");

                    //create string from xml tree
                    //File file2 = new File("/home/myhome/an_xml_file.xml");
                    //FileOutputStream output = new FileOutputStream(file);
                    //Result streamResult = new StreamResult(output);
                    
                    Result streamResult = new StreamResult(file);
                    DOMSource source = new DOMSource(doc);
                    trans.transform(source, streamResult);
                    
                    //output.close();

                    
                } else {
                    throw new XmlDataException("XmlData already exists"); 
                }


            } catch (TransformerException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (XPathExpressionException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (SAXException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (FileNotFoundException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (IOException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (ParserConfigurationException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            }

            
        }
        
}

Thanks in advance.

[John Jai]

Try appending the XmlDataElement created to the document.

doc.appendChild(XmlDataElement);

[Hugo Alberto Bedolla]

John Jai wrote:Try appending the XmlDataElement created to the document.

doc.appendChild(XmlDataElement);

Thanks for your reply... done, I got:

org.w3c.dom.DOMException: HIERARCHY_REQUEST_ERR: An attempt was made to insert a node where it is not permitted.
at com.sun.org.apache.xerces.internal.dom.CoreDocumentImpl.insertBefore(CoreDocumentImpl.java:391)
at com.sun.org.apache.xerces.internal.dom.NodeImpl.appendChild(NodeImpl.java:235)

Code is (look around line 35):

public void addXmlData(XmlData xmlData) throws XmlDataException {
        
        synchronized (this) {
            try {
                DocumentBuilderFactory dbfac = DocumentBuilderFactory.newInstance();
                DocumentBuilder docBuilder = dbfac.newDocumentBuilder();
                
                File file = new File("/home/myhome/an_xml_file.xml");
                
                Document doc = docBuilder.parse(file);
                
                XPath xpath = XPathFactory.newInstance().newXPath();
                
                String XmlDataName = xmlData.getXmlDataName();
                
                String search = "//XmlData[@name='" + XmlDataName + "']";
                
                XPathExpression expr = xpath.compile(search);
                
                Node result = (Node)expr.evaluate(doc, XPathConstants.NODE);
                
                if(result == null) {
                    
                    Element XmlDataElement = doc.createElement("XmlData");
                    XmlDataElement.setAttribute("name", xmlData.getXmlDataName());
                    
                    Element descriptionElement = doc.createElement("XmlData-description");
                    descriptionElement.setTextXmlData(xmlData.getXmlDataDescription());
                    XmlDataElement.appendChild(descriptionElement);
                    
                    Element baseLocaleElement = doc.createElement("base-locale");
                    baseLocaleElement.setAttribute("locale", xmlData.getXmlDataLocale());
                    XmlDataElement.appendChild(baseLocaleElement);                    
                    
                    doc.appendChild(XmlDataElement);

                    //set up a transformer
                    TransformerFactory transfac = TransformerFactory.newInstance();
                    Transformer trans = transfac.newTransformer();
                    trans.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
                    //trans.setOutputProperty(OutputKeys.INDENT, "yes");

                    //create string from xml tree
                    //File file2 = new File("/home/myhome/an_xml_file.xml");
                    //FileOutputStream output = new FileOutputStream(file);
                    //Result streamResult = new StreamResult(output);
                    
                    Result streamResult = new StreamResult(file);
                    DOMSource source = new DOMSource(doc);
                    trans.transform(source, streamResult);
                    
                    //output.close();

                    
                } else {
                    throw new XmlDataException("XmlData already exists"); 
                }


            } catch (TransformerException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (XPathExpressionException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (SAXException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (FileNotFoundException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (IOException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (ParserConfigurationException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            }

            
        }
        
}

[John Jai]

Then try where you have to append the XmlDataElement. If that should be under the root, then get the doc.getDocumentElement() and append the XmlDataElement to it.

[Rob Spoor]

See also this duplicate thread.

[Campbell Ritchie]

Rob Spoor wrote:See also this duplicate thread.

Which is in a far more appropriate location. Thank you for noticing, Rob. I am moving this thread.

[Hugo Alberto Bedolla]

John Jai wrote:Then try where you have to append the XmlDataElement. If that should be under the root, then get the doc.getDocumentElement() and append the XmlDataElement to it.

Hi John: Fine, that works; I was deducing when I call "Element XmlDataElement = doc.createElement("XmlData");" DOM knows both is a new node, and where I wanna put the new node (considering is the next new node inside the document) but it is not the case. Here's the new code calling the root node and appending a new XmlData node to it, that solution worked for me (Lines 34, 35):

public void addXmlData(XmlData xmlData) throws XmlDataException {
        
        synchronized (this) {
            try {
                DocumentBuilderFactory dbfac = DocumentBuilderFactory.newInstance();
                DocumentBuilder docBuilder = dbfac.newDocumentBuilder();
                
                File file = new File("/home/myhome/an_xml_file.xml");
                
                Document doc = docBuilder.parse(file);
                
                XPath xpath = XPathFactory.newInstance().newXPath();
                
                String XmlDataName = xmlData.getXmlDataName();
                
                String search = "//XmlData[@name='" + XmlDataName + "']";
                
                XPathExpression expr = xpath.compile(search);
                
                Node result = (Node)expr.evaluate(doc, XPathConstants.NODE);
                
                if(result == null) {
                    Element XmlDataElement = doc.createElement("XmlData");
                    XmlDataElement.setAttribute("name", xmlData.getXmlDataName());
                    
                    Element descriptionElement = doc.createElement("XmlData-description");
                    descriptionElement.setTextXmlData(xmlData.getXmlDataDescription());
                    XmlDataElement.appendChild(descriptionElement);
                    
                    Element baseLocaleElement = doc.createElement("base-locale");
                    baseLocaleElement.setAttribute("locale", xmlData.getXmlDataLocale());
                    XmlDataElement.appendChild(baseLocaleElement);   

                    Element rootElement = doc.getDocumentElement(); 
                    rootElement.appendChild(contentElement);                  
                    
                    //set up a transformer
                    TransformerFactory transfac = TransformerFactory.newInstance();
                    Transformer trans = transfac.newTransformer();
                    trans.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
                    //trans.setOutputProperty(OutputKeys.INDENT, "yes");

                    //create string from xml tree
                    //File file2 = new File("/home/myhome/an_xml_file.xml");
                    //FileOutputStream output = new FileOutputStream(file);
                    //Result streamResult = new StreamResult(output);
                    
                    Result streamResult = new StreamResult(file);
                    DOMSource source = new DOMSource(doc);
                    trans.transform(source, streamResult);
                    
                    //output.close();

                    
                } else {
                    throw new XmlDataException("XmlData already exists"); 
                }


            } catch (TransformerException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (XPathExpressionException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (SAXException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (FileNotFoundException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (IOException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (ParserConfigurationException ex) {
                Logger.getLogger(XmlDataManager.class.getName()).log(Level.SEVERE, null, ex);
            }

            
        }
        
}

Again, thanks so much for your help.