Changing XML document nesting

Question

Hello,
I am trying to change the xml nesting (parent - child) relationships for a returned xml query. I am getting java.lang.Nullpointerexcetion on the following line of code:
tempNode := xmldom.appendChild(newRootNode,oldNode);
I have initialized in the following manner:
p xmlparser.parser;
doc xmldom.DOMDocument;
len number;
newlen number;
newDOMDoc xmldom.DOMDocument;
oldDOMDoc xmldom.DOMDocument;
newNodeList xmldom.DOMNodeList;
oldNodeList xmldom.DOMNodeList;
newNode xmldom.DOMNode;
oldNode xmldom.DOMNode;
tempNode xmldom.DOMNode;
newRootNode xmldom.DOMNode;
newPatientNode xmldom.DOMNode;
newPatientDeathNode xmldom.DOMNode;
newParentNode xmldom.DOMNode;
newDrugNode xmldom.DOMNode;
newElem xmldom.DOMElement;
BEGIN
/* Initialize */
ClbIDoc := IDomDoc;
p := xmlparser.newparser;
newDOMDoc :=xmldom.newDOMDocument;
newRootNode := xmldom.makeNode(newDOMDoc);
newElem := xmldom.createElement(newDOMDoc,'root');
newRootNode := xmldom.appendChild(newRootNode,xmldom.makeNode(newElem));
xmlparser.parseclob(p, ClbIDoc);
tempNode := xmldom.makeNode(newDOMDoc);
-- get old document
oldDOMDoc := xmlparser.getDocument(p);
-- get the message header
oldNodeList := xmldom.getElementsByTagName(oldDOMDoc,'messageheader');
-- there should be only one header in the document
oldNode := xmldom.item(oldNodeList, 0);
-- put the header into the new document
tempNode := xmldom.appendChild(newRootNode,oldNode);
-- get the saftey report
oldNodeList := xmldom.getElementsByTagName(oldDOMDoc,'report');
-- there should be only one report in the document
oldNode := xmldom.item(oldNodeList, 0);
-- put the saftey report into the new document
tempNode := xmldom.appendChild(newRootNode,oldNode);
Any help would be greatly appreciated!!
Also, if there is a more convienent method for changing the nesting I would be open to other suggestions.
Thanks,
Scott
null

Answer 1

I'm not sure if this will be of help or not but I have a custom action handler that writes XML out to the file system but moves the nodes around slightly befor writing the file. After a day of trial and error I finaly found a method tat works, here is the code:
import java.io.*;
import java.lang.String.*;
import java.sql.SQLException;
import oracle.xml.parser.v2.XMLDocument;
import oracle.xml.xsql.*;
import oracle.xml.xsql.actions.XSQLIncludeXSQLHandler;
import org.w3c.dom.*;
public class WriteXMLToFile extends XSQLActionHandlerImpl
//the first three variables are parameter names the action handler looks for
private static final String BASETAG = "base-tag";
private static final String FILEATTR = "file";
private static final String DIRATTR = "dir";
//this fourth one is the base directory for saving the files. The user may specify
//and existing directory with in this directory but cannot escape out of it
private static final String BaseDir = "/u01/oracle/ias10210/xdk/java/xsql/XMLRepository/";
public void handleAction(Node rootNode) throws SQLException
//The Element actElt is a refrence to the document that is used to get
//the parameter values if they exist
Element actElt = getActionElement();
//this block gets the values for the three parameters
String targetFileName = getAttributeAllowingParam(FILEATTR, actElt);
String targetDirName = getAttributeAllowingParam(DIRATTR, actElt);
String baseTagName = getAttributeAllowingParam(BASETAG, actElt);
//The filePathName will be used to create a directory/file path to be appended to
//the BaseDir constant when saving the file
String filePathName = "";
//searchNode is used to keep track of the current node name be looked for
String searchNode = "";
int oldIndex = 0;
int currentIndex = 0;
boolean keepLooking = true;
boolean moveSuccesfull = false;
// Must have a "file" attribute on the action element
if (targetFileName == null | | targetFileName.equals(""))
this.reportMissingAttribute(rootNode, FILEATTR);
return;
// Must have a "base-tag" attribute on the action element
if (baseTagName == null | | baseTagName.equals(""))
this.reportMissingAttribute(rootNode, BASETAG);
return;
//The base-tag must start with a / so our search through the string works right
if (!baseTagName.startsWith("/"))
this.reportError(rootNode, "The 'base-tag' must begin with a '/'.");
return;
//The base-tag must also end with a / so our search through the string works right
if (!baseTagName.endsWith("/"))
this.reportError(rootNode, "The 'base-tag' must end with a '/'.");
return;
//The base-tag must also have a / somwhere in the middle so we have a from and a too
if (!baseTagName.equals("/") && baseTagName.indexOf("/", 1) == (baseTagName.length() - 1))
this.reportError(rootNode, "The 'base-tag' must have 2 or more nodes in it.");
return;
//this if/else checks to see if the target dir was passed or not
if (targetDirName == null | | targetDirName.equals(""))
//if not our PathName is just the filename
filePathName = targetFileName;
else
//if so then the PathName is the dirname/filename
filePathName = targetDirName + "/" + targetFileName;
if (filePathName.indexOf("..") != -1)
this.reportError(rootNode, "Invalid directory name.");
return;
//get a refrence to the document
Document XMLDoc = rootNode.getOwnerDocument();
//break the child nodes down into a NodeList for parsing
NodeList currentNodeList = XMLDoc.getChildNodes();
//the dead node is what we will temporarily store the node
//we are deleting in
Node deadNode = null;
//if the base-tag was just / then we don't edit the layout at all
if (!baseTagName.equals("/"))
//if not ....
//search for the next occurance of a / in the path
currentIndex = baseTagName.indexOf("/", oldIndex + 1);
//the currentIndex will be -1 if a / was not found
if (currentIndex >= 0)
//if it was found set the    searchNode to the name of that substring
searchNode = baseTagName.substring(oldIndex + 1, currentIndex);
//set the index so we can keep track of where we are in the string
oldIndex = currentIndex;
//loop through the child nodes of the root document looking for out first match
for (int index = 0; index < currentNodeList.getLength(); index++)
//if the name of the node is equal to the search node we found it
if (currentNodeList.item(index).getNodeName().equals(searchNode))
//remove the node from the document and store it in a temporary
//node and get out of the for
deadNode = XMLDoc.removeChild(currentNodeList.item(index));
index = currentNodeList.getLength();
//create the NodeList from the removed Node
currentNodeList = deadNode.getChildNodes();
//find the next / in the tag string
currentIndex = baseTagName.indexOf("/", oldIndex + 1);
//if a / was found
if (currentIndex >= 0)
//get the name of the Node we are now looking for
searchNode = baseTagName.substring(oldIndex + 1, currentIndex);
oldIndex = currentIndex;
//if there was a node removed and the searchNode has a name and the node index is >= 0
while (deadNode != null && !searchNode.equals("") && currentIndex >= 0 && keepLooking)
keepLooking = false;
//loop through the nodes in the node list
for (int index = 0; index < currentNodeList.getLength(); index++)
//if the node we are looking for is found
if (currentNodeList.item(index).getNodeName().equals(searchNode))
//look for the next / in the tag string
currentIndex = baseTagName.indexOf("/", oldIndex + 1);
//if one is found
if (currentIndex >= 0)
//get the next node name from the tag string and set the node
//list to the children of the node we just found
currentNodeList = currentNodeList.item(index).getChildNodes();
searchNode = baseTagName.substring(oldIndex + 1, currentIndex);
oldIndex = currentIndex;
keepLooking = true;
//if one is not found
else
moveSuccesfull = true;
//set the search node to "" since we are done looking
searchNode = "";
//add the node back to the root document
XMLDoc.appendChild(currentNodeList.item(index));
//get out of the for
index = currentNodeList.getLength();
if (!moveSuccesfull)
XMLDoc.appendChild(deadNode);
//if the document is not null
if (XMLDoc != null)
try
//try to write the file to the specified path and name
FileWriter fw = new FileWriter(BaseDir + filePathName);
((XMLDocument)XMLDoc).print(new PrintWriter(new BufferedWriter(fw)));
catch (IOException iox)
//if it fails report the error
this.reportError(rootNode, "Error writing file " + filePathName);
return;
else
//if the document is null report the error
this.reportError(rootNode, "No Document to write.");
return;
}It's fairly long and I'm not sure how clear it is since I just whipped it up for a proof of concept. If you have any question feel feel to email.
Hope it helps,
-Eric Dalquist