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javaxpathdom4j

dom4j XPath not node-type

I try to get just a part of an attribute (could also be a part of an element), but no luck so far. The exception I get is "Invalid XPath expression: //@att/tokenize(., ' ')[.][position() = 1] Expected node-type". I'm using dom4j 1.6.1.

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.XPath;
import org.dom4j.xpath.DefaultXPath;


public class TestXPathString {

    /**
     * @param args
     * @throws DocumentException 
     */
    public static void main(String[] args) throws DocumentException {
        Document doc = DocumentHelper
                .parseText("<x><y att='I just need the first word' /></x>");
        XPath xpath = new DefaultXPath("//@att/tokenize(., ' ')[.][position() = 1]");
        Object result = xpath.evaluate(doc);
        System.out.printf("Type: %s, Value: %s\n", result.getClass()
                .getSimpleName(), result);
    }

}

It doesn't work with

doc.selectObject("//@att/substring-before(., ' ')");

either.

Any ideas?

Solution

  • Applying functions in axis steps is an XPath 2.0 feature; Java (and dom4j) only support XPath 1.0. You cannot do this.

    If you only expect a single result, use substring-before(//@att, ' '). Otherwise, pass the whole attribute value to Java and do the string manipulation outside XPath.

    You might consider plugging a more powerful XPath/XQuery engine, like Saxon, BaseX or other native XML databases with Java APIs available.