Invalid XSD schema using libxmljs with nodejs

Question

I've posted an issue on libxmljs repository and it was closed because they think that this isn't a problem at the level of the lib. So I post it here.

I'm trying to validate a XLIFF file with a XML schema provided by OASIS but I keep receiving an error with the XSD.

Error: Invalid XSD schema at Document.validate (/Users/fluxb0x/Tests/xliff_parser/node_modules/libxmljs/lib/document.js:73:17) at Request._callback (/Users/fluxb0x/Tests/xliff_parser/main.js:25:21) at Request.self.callback (/Users/fluxb0x/Tests/xliff_parser/node_modules/request/request.js:199:22) at Request.emit (events.js:98:17) at Request. (/Users/fluxb0x/Tests/xliff_parser/node_modules/request/request.js:1160:14) at Request.emit (events.js:117:20) at IncomingMessage. (/Users/fluxb0x/Tests/xliff_parser/node_modules/request/request.js:1111:12) at IncomingMessage.emit (events.js:117:20) at _stream_readable.js:938:16 at process._tickCallback (node.js:419:13)

I've use Oxygen XML editor to test the validation and it goes without problem.

This is the XLIFF file exported by me : en.xliff

This is the XSD file provided by OASIS : xliff_schema.xsd

Pretty big file.

Thank you for the help.

Answer 1

If the XSD schema contains xsd:import elements with filesystem-relative schemaLocation attributes, the libxmljs.parseXml() function accepts a baseUrl option that can be used to set the location of these.

const xsdDocument = libxmljs.parseXml(xsdString, { baseUrl: "/path/to/xsd/" });

This avoids the need to temporarily change working directory. Watch out for the trailing slash too.

Answer 2

As you noted on the libxmljs bug tracker, libxmljs throws an error when validating an XML with a schema file which imports another.

<xsd:import namespace="http://www.w3.org/XML/1998/namespace" schemaLocation="./xml.xsd"/>

This happens because the relative path in schemaLocation is calculated on the process current working directory. A workaround is changing the directory before validating:

fs.readFile(schemaPath, { encoding: 'utf8' }, function (err, xsd) {
    if (err) cb (err);

    var cwd = process.cwd();
    process.chdir(path.dirname(schemaPath));

    var xsdDoc = libxml.parseXml(xsd);
    var xmlDoc = libxml.parseXml(content);

    var output = xmlDoc.validate(xsdDoc);
    process.chdir(cwd);

    cb(undefined, xmlDoc.validationErrors);
});

I'm not sure how libxml handles this though: maybe the referenced file is loaded synchronously and I suppose this is suboptimal.

This workaround is only for local files, I don't know how to resolve in case of a remote schemaLocation, like in your example (schemaLocation="http://www.w3.org/2001/xml.xsd"/>)

Even if it's not a real solution I think this might help.