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Managed results after XQuery call from java
Added by Anonymous almost 19 years ago
Legacy ID: #3265116
Legacy Poster: bruno souche (bsouche)
Hi, First i want to apologize for my poor english, and i hope that you ll understand
me. I started to learn XQuery/XPath few weeks ago, and now i encounter a problem using
Saxon (not a bug, just lack of knowledges). My program is quite simple. I create all
business rules and functions in XQuery, all data are stocked in XML files (all work
fine, created and tested using XMLSpy 2005 Home Edition). As u can see, i use the
'portability' concept, the developper must create the user interface in his favorite
language. To demonstrate how the application works, i've started to create a program
using java language (Sun JDK 1.5.0_02 on XP platform) and Saxon-8.4B API. My problem
occurs when i call XQuery function with Saxon, not the call itself, but i don't know how
to manage my returned element! When i display it or write it to a file i only see the
text() value of the element, not the element itself. In Saxonica online documentation
(Result Format chapter) it's said that i ve to 'wrap' my result. But i don't find how to
do in samples or on the web. I hope that u can understand my awful english and u can
help me. Thanx in advance. Bruno PS:You ll find my java code at the end of this post. If
you need i can send you my XQuery code. JAVA CODE
********************************************************* public void compute(){ try {
Configuration config = new Configuration(); StaticQueryContext sqc new
StaticQueryContext(config); XQueryExpression exp = sqc.compileQuery(new
FileReader(request)); XQueryFunction temp = null; Controller controller =
exp.getController();//controller UserFunction fn1 =
exp.getStaticContext().getUserDefinedFunction("rml.ns",
"getCritical", 3); //values to call function Value[] arglist = new
Value[3]; arglist[0] = new IntegerValue(100); arglist[1] = new
StringValue("E"); arglist[2] = new StringValue(filepath); //CALL
ValueRepresentation result = fn1.call(arglist, controller); //Display result
FileOutputStream fos = new FileOutputStream(new File("d:/test.txt"));
System.out.println("getCritical("+arglist[0]+","+arglist[1]
+ ","+arglist[2] +") : " +
result+"\n\n"); fos.write(result.toString().getBytes()); fos.close();
} catch (XPathException e) { e.printStackTrace(); } catch (FileNotFoundException e) {
e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } }
**************************************************** END JAVA CODE
Legacy ID: #3265151
Legacy Poster: Michael Kay (mhkay)
The interface you are using, which allows you to call a specific function in your
query module, is a fairly low-level interface that was designed primarily for
integrators rather than end users. It's a very efficient interface, but it achieves this
partly by doing rather little checking and conversion of parameters and results. It
wouldn't be my recommendation for a novice user. You can use it if you want: but you
have to inspect the ValueRepresentation that comes back to see what kind of object you
have got, and process it accordingly. Just doing toString() on it won't be very useful.
In fact a ValueRepresentation is either a Value or a NodeInfo, so these are the only
cases you need to consider. I would recommend that you use instead the approach
documented at http://www.saxonica.com/documentation/using-xquery/embedding.html
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