[Interest] QXmlSchemaValidator with local schema files

Roger Leigh rleigh at codelibre.net
Sat Feb 16 13:28:47 CET 2019

Hi folks,

I'm wanting to validate some XML with QXmlSchemaValidator, but I want it 
to use local copies of the schema files.  I'm doing this:

   std::string xml = read_file();

   CustomResolver r;
   QXmlSchemaValidator v;

   QByteArray raw_data(s.c_str(), s.size());

   bool valid = v.validate(raw_data);

This is working.  It's validating against the schema file(s) in the 
input document and returning true or false currectly on success or 
error.  However... it's not calling the resolve() function in the URI 
resolver, so I can't map these schema URIs to local files.  So every 
invocation requires network activity and is quite slow.

Is this the intended purpose of setUriResolver()?  Should this be 
expected to work?

I also tried "v.schema().setUriResolver(&r);" since I saw this also had 
an option for setting a URI resolver, but this has no effect.

Is there a way of achieving this?  With Xerces-C++, I was using a custom 
EntityResolver for this purpose, which worked perfectly to search a 
local tree of XML catalogue files.  I want to achieve the equivalent 
behaviour with QtXmlPatterns/QtXml.

My resolve() function is currently a no-op:

   CustomResolver::resolve(const QUrl &relative,
                           const QUrl &baseURI) const
     std::cerr << "QT resolve URI: rel="
               << relative.toString().toStdString() << " base="
               << baseURI.toString().toStdString() << std::endl;
     return baseURI.resolved(relative);

I never see any output, so I'm fairly confident it's not being called.


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