Hi Fayyaz,
>>I have found an error in the web.xml file,
Good job! I found an error in your code so that makes us even :)
It looks like you removed the line in the "openExampleIndex" method which opens
the searcher.
That explains your null pointer.
The problem you found in the web.xml isn't actually an error but is potentially
misleading. In the "UserQuery" tag in the XSL there is a "fieldName" tag which
is set to "description". The "jobDescription" default fieldname passed to the
XML parser would only be in effect for any <UserQuery> tags that didn't specify
a fieldName..
BTW, in the source distribution there are full "DTDdocs" for the XML syntax in
contrib\xml-query-parser\docs
Cheers
Mark
----- Original Message ----
From: syedfa <fayyazud...@gmail.com>
To: java-user@lucene.apache.org
Sent: Wed, 23 December, 2009 5:03:00
Subject: Re: Need help with XML Query Parser example in Lucene 3.0
I have found an error in the web.xml file, however, this DID NOT fix the
problem. Inside the web.xml file, there is the following snippet:
<init-param>
<description>
Default field used in standard Lucene QueryParser used in UserQuery
tag</description>
<param-name>defaultStandardQueryParserField</param-name>
<param-value>jobDescription</param-value>
</init-param>
the <param-value> here should be IMHO "description", as neither the
query.xsl file, nor index.jsp file contain any tags/values called
"jobDescription", only "description". I hope the contributors to the Lucene
project take note of this, or please show me the error of my ways. Having
said that, as I mentioned earlier, despite making this correction, I am
still getting the above "NullPointerException". Can anyone see where I am
going wrong?
Thanks again to all who reply.
Sincerely;
Fayyaz
syedfa wrote:
>
> Dear fellow Java developers:
>
> I am trying to run the XML Query Parser example that comes with Lucene 3.0
> source distribution. I have the application structured identical to the
> one you download, and I am trying to run it in eclipse. When I launch the
> application, fill out the form that appears on index.jsp, and then submit
> it to search the index, I get the following error 505:
>
> javax.servlet.ServletException: Error processing query
>
> org.apache.lucene.xmlparser.webdemo.FormBasedXmlQueryDemo.doPost(FormBasedXmlQueryDemo.java:124)
> javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
> javax.servlet.http.HttpServlet..service(HttpServlet.java:803)
>
>
> root cause
>
> java.lang..NullPointerException
>
> org.apache.lucene.xmlparser.webdemo.FormBasedXmlQueryDemo.doPost(FormBasedXmlQueryDemo.java:107)
> javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
> javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
>
>
> I absolutely have no idea why this is happening, as I even structured the
> package of the servlet in eclipse identical to the way it is in the
> example. I have attached my entire servlet, "FormBasedXmlQueryDemo"
> below:
>
> public class FormBasedXmlQueryDemo extends HttpServlet {
> private static final long serialVersionUID = 1L;
>
> private QueryTemplateManager queryTemplateManager;
> private CorePlusExtensionsParser xmlParser;
> private IndexSearcher searcher;
> private Analyzer analyzer = new
> StandardAnalyzer(org.apache.lucene.util.Version.LUCENE_CURRENT);
>
> public FormBasedXmlQueryDemo() {
> super();
> // TODO Auto-generated constructor stub
> }
>
> @Override
> public void init(ServletConfig config) throws ServletException {
> // TODO Auto-generated method stub
> super.init(config);
>
> try{
>
> openExampleIndex();
>
> String xslFile=config.getInitParameter("xslFile");
> String defaultStandardQueryParserField =
> config.getInitParameter("defaultStandardQueryParserField");
> queryTemplateManager = new
> QueryTemplateManager(getServletContext().getResourceAsStream("/WEB-INF/" +
> xslFile));
> xmlParser = new
> CorePlusExtensionsParser(defaultStandardQueryParserField, analyzer);
>
> }catch(Exception e){
> throw new ServletException("Error loading query template", e);
> }
> }
>
> protected void doGet(HttpServletRequest request, HttpServletResponse
> response) throws ServletException, IOException {
>
> }
>
> @Override
> protected void doPost(HttpServletRequest request, HttpServletResponse
> response) throws ServletException, IOException {
> // TODO Auto-generated method stub
>
> Properties completedFormFields = new Properties();
> Enumeration pNames = request.getParameterNames();
>
> while (pNames.hasMoreElements()){
>
> String propName = (String) pNames.nextElement();
> String value = request.getParameter(propName);
>
> if ((value != null) && (value.trim().length()>0)){
> completedFormFields.setProperty(propName, value);
> }
> }
>
> try{
> org.w3c.dom..Document xmlQuery =
> queryTemplateManager.getQueryAsDOM(completedFormFields);
> Query query = xmlParser.getQuery(xmlQuery.getDocumentElement());
> TopDocs topDocs = searcher.search(query, 10);
>
> if (topDocs != null) {
> ScoreDoc[] sd = topDocs.scoreDocs;
> Document[] results = new Document[sd.length];
>
> for(int i = 0; i < results.length; i++){
>
> results[i] = searcher.doc(sd[i].doc);
> request.setAttribute("results", results);
> }
> }
>
> RequestDispatcher dispatcher =
> getServletContext().getRequestDispatcher("/index..jsp");
> dispatcher.forward(request, response);
> }
> catch(Exception e){
> throw new ServletException("Error processing query", e);
> }
> }
>
> private void openExampleIndex() throws CorruptIndexException, IOException
> {
>
>
> RAMDirectory rd = new RAMDirectory();
> IndexWriter writer = new IndexWriter(rd, analyzer,
> IndexWriter.MaxFieldLength.LIMITED);
> InputStream dataIn =
> getServletContext().getResourceAsStream("/WEB-INF/data.tsv");
> BufferedReader br = new BufferedReader(new InputStreamReader(dataIn));
> String line = br.readLine();
>
> while (line != null){
>
> line = line.trim();
> if (line.length() > 0){
>
> StringTokenizer st = new StringTokenizer(line, "\t");
> Document doc = new Document();
> doc.add(new Field("location",st.nextToken(),Field.Store.YES,
> Field.Index.ANALYZED_NO_NORMS));
> doc.add(new Field("salary",st.nextToken(),Field.Store.YES,
> Field.Index.ANALYZED_NO_NORMS));
> doc.add(new Field("type",st.nextToken(),Field.Store.YES,
> Field.Index.ANALYZED_NO_NORMS));
> doc.add(new
> Field("description",st.nextToken(),Field.Store.YES,
> Field.Index.ANALYZED));
> writer.addDocument(doc);
> }
>
> line = br.readLine();
> }
>
> writer.close();
> }
>
> }
>
>
>
> When I was tracing through the code, it appears that it was throwing the
> exception just as it tried to process the line:
>
> TopDocs topDocs = searcher.search(query, 10);
>
> Does anyone know where I am going wrong?
>
> Thanks in advance to all who reply.
>
--
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