Identity Constraint in XML Schema

Question

Hi,
I am trying to validate an xml so that the value of one tag<ns0:transid> should be unique. The XML is given below:
<?xml version="1.0" encoding="UTF-8"?>
<ns0:transactions  xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
   xmlns:ns0='http://xml.netbeans.org/schema/testSchema'
   xsi:schemaLocation='http://xml.netbeans.org/schema/testSchema src\testSchema.xsd'>
       <ns0:transaction>
           <ns0:transid>1</ns0:transid>
           <ns0:name>abc</ns0:name>
       </ns0:transaction>
       <ns0:transaction>
           <ns0:transid>1</ns0:transid>
           <ns0:name>abc</ns0:name>
       </ns0:transaction>
       <ns0:transaction>
           <ns0:transid>3</ns0:transid>
           <ns0:name>abc</ns0:name>
       </ns0:transaction>
</ns0:transactions>The The Scheme is given below
<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
            targetNamespace="http://xml.netbeans.org/schema/testSchema"
            xmlns:tns="http://xml.netbeans.org/schema/testSchema"
            elementFormDefault="qualified">
    <xsd:element name="transactions">
        <xsd:complexType>
            <xsd:sequence>
                <xsd:element name="transaction" maxOccurs="unbounded">
                    <xsd:complexType>
                        <xsd:sequence>
                            <xsd:element name="transid" type="xsd:int"/>
                            <xsd:element name="name" type="xsd:string"/>
                        </xsd:sequence>
                    </xsd:complexType>
                    <xsd:key name="transaction">
                        <xsd:selector xpath="transaction"/>
                        <xsd:field xpath="transid"/>
                    </xsd:key>
                </xsd:element>
            </xsd:sequence>
        </xsd:complexType>
    </xsd:element>
</xsd:schema>The validation code is given below:
package schematest;
import java.io.File;
import java.io.IOException;
import javax.xml.XMLConstants;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Source;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;
import javax.xml.validation.Validator;
import org.w3c.dom.Document;
import org.xml.sax.SAXException;
* @author irfan.masood
public class Main {
     * @param args the command line arguments
    public static void main(String[] args) {
        try {
            // Parse an XML document into a DOM tree.
            DocumentBuilder parser =
                    DocumentBuilderFactory.newInstance().newDocumentBuilder();
            Document document = parser.parse(new File("test.xml"));
            // Create a SchemaFactory capable of understanding WXS schemas.
            SchemaFactory factory =
                    SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
            // Load a WXS schema, represented by a Schema instance.
            Source schemaFile = new StreamSource(new File("src/testSchema.xsd"));
            Schema schema = factory.newSchema(schemaFile);
            // Create a Validator object, which can be used to validate
            // an instance document.
            Validator validator = schema.newValidator();
            // Validate the DOM tree.
            validator.validate(new DOMSource(document));
        } catch (ParserConfigurationException e) {
            // exception handling
            e.printStackTrace();
        } catch (SAXException e) {
            // exception handling - document not valid!
            e.printStackTrace();
        } catch (IOException e) {
            // exception handling
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        catch( Throwable t ){
            t.printStackTrace();
}You can see that the tag (<ns0:transid>) on which the key constraint is applied have duplicate values but still the xml is validated successfully. It should not be validating successfully, please see where I am wrong!
Many Thanks!
Irfan

Answer 1

my guess is that the "xsd:key" constraint needs to be in the "transactions" element, not the "transaction" element.