Programatically determining which node in an XML document caused validation against its XML Schema to fail

Question

My input is a well-formed XML document and a corresponding XML Schema document. What I would like to do is determine the location within the XML document that causes it to fail validation against the XML Schema document. I could not figure out how to do this using the standard validation approach in Java:

SchemaFactory schemaFactory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
Schema schema = schemaFactory.newSchema(... /* the .xsd source */);
Validator validator = schema.newValidator();
DocumentBuilderFactory ...
DocumentBuilder ...
Document document = DocumentBuilder.parse(... /* the .xml source */);
try {
    validator.validate(new DOMSource(document));
    ...
} catch (SAXParseException e) {
    ...
}

I have toyed with the idea of getting at least the line and column number from SAXParseException, but they're always set to -1, -1 on validation error.

Answer 1

You won't get schema validation errors reported this way. If you really want line and column information, you need to set an error handler, i.e.

try {
   validator.setErrorHandler(handler);
   validator.validate(...);
} catch (SAXParseException e) {
   // Use handler info, or log it in handler
}

Here's the interface you need to implement: ErrorHandler

Answer 2

Take a look at the https://jaxb2-commons.dev.java.net/xpath-tracker/ project. It was designed for Jaxb, but I think it would work outside of this since it is an XMLFilter.

Answer 3

A DOM does not retain information about its source -- in most cases it's irrelevant, and DOM is meant to be manipulated (ie, any location information would be incorrect).

The solution is to validate at the time you parse: call DocumentBuilderFactory.setSchema() before creating the DocumentBuilder.