Re: [Exist-open] XPathAPI

[Wolfgang M. <me...@if...>]

Hi,

actually, you don't have to use the XPathAPI for the post-processing. eXi=
st=20
supports nested queries, i.e. you can execute a second query on the resou=
rce=20
you retrieved from a first query. To use this feature, you have to cast y=
our=20
XPathService to org.exist.xmldb.XPathServiceImpl. Then you can do:

while(results.hasMoreResources()) {
=09...
=09XMLResource resource =3D (XMLResource)results.nextResource();
=09...
=09ResultSet rs =3D ((org.exist.xmldb.XPathQueryService)service).query(re=
source,=20
"/canal/canal_name");
=09c.setResource((String)rs.getResource(0L).getContent());
}

This should be much safer than using xalan for the post-processing. I'm n=
ot=20
sure if eXist's DOM is fully compatible with xalan (though I know it work=
s=20
with Jaxen).

Regards,

Wolfgang


On Friday 11 April 2003 01:16 am, Matthew Furister wrote:
> I am currently using eXist9.1 and am pretty new to the program. I have
> embedded it into a java application that I am writing and am trying to =
use
> XPathAPI to get the values of the element.
>
> What I want is the value only. The problem is that XPathAPI.eval(node,
> string) seems to hang. It does not throw an exception, yet it will not =
move
> on from this call.
>
> When I print out the node, everything seems to be ok.
>
> I am on a severe time crunch, so any immediate ideas will be extremly
> helpful. If anyone has ANY ideas, please post them immediatly.
>
> Thanks for your help....
>
> -- Matt
>
> Example:
> =09<canal>
> =09=09<canal_name>Canal1</canal_name>
> =09=09<canal_resource>canal_1</canal_resource>
> =09</canal>
>
>
>
> The Code:
> //<imports>
> import java.util.Vector;
> import java.util.Hashtable;
> import org.xmldb.api.base.*;
> import org.xmldb.api.modules.*;
>
> import org.w3c.dom.*;
>
> import org.apache.xpath.*;
> import org.apache.xpath.objects.*;
>
> //<method>
>  public void addResults(ResourceIterator results) {
>        System.out.println("ADDING RESULTS");
>       try {
>           System.out.println("TRYING");
>          while (results.hasMoreResources()) {
>             System.out.println("WHILE...");
>             // Create a new canal instance to add to Group
>             Canal c =3D new Canal();
>
>             // Retrieve the next node
>             XMLResource resource =3D (XMLResource) results.nextResource=
();
>
>             // Cast to Dom Node
>
>             Node originalnode =3D resource.getContentAsDOM();
>             System.out.println(originalnode.toString());
>
>             // Get the document key for this node for later use
>             String dockey =3D resource.getDocumentId();
>             c.setDocKey(dockey);
>
>             // Use Xalan xpath parser to extract data, store into hasta=
ble
>             XObject xo =3D new XObject();
>             XPathAPI xp =3D new XPathAPI();
>             xo =3D xp.eval(originalnode, "/canal/canal_name");
>             System.out.println(xo.toString());
>             c.setName(xo.toString());
>
>             xo =3D XPathAPI.eval(originalnode, "/canal/canal_resource")=
;
>             c.setResource(xo.toString());
>
>             // Add person to group
>             this.add(c);
>          }
>       }
>       catch (Exception e) {
>          e.printStackTrace();
>       }
> System.out.println("OUT OF WHILE");
>    }
>
>
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--=20
Wolfgang Meier
Darmstadt University of Technology
TELOS Working Group, Dept. of Soc.
Residenzschlo=DF
D-64283 Darmstadt, Germany
+49 (0)6151-163215
mailto:me...@if...
http://www.sozionet.org
=20