xml file validation with in-memory schema in xerces c++ - c++

Question

#include <xercesc/framework/Wrapper4InputSource.hpp>
#include <xercesc/util/XMLString.hpp>
#include <xercesc/sax2/SAX2XMLReader.hpp>
#include <xercesc/parsers/XercesDOMParser.hpp>
#include <xercesc/dom/DOMLSParser.hpp>
#include <xercesc/dom/DOMImplementation.hpp>
#include <xercesc/sax2/XMLReaderFactory.hpp>
#include <xercesc/framework/MemBufInputSource.hpp>
#include <xercesc/framework/LocalFileInputSource.hpp>
#include <xercesc/sax/ErrorHandler.hpp>
#include <xercesc/sax/SAXParseException.hpp>
#include <xercesc/sax/Parser.hpp>
#include <xercesc/validators/common/Grammar.hpp>
class CErrorHandler : public xercesc::DefaultHandler
{
public:
CErrorHandler();
virtual ~CErrorHandler();
void startElement(const XMLCh* const uri,
const XMLCh* const localname,
const XMLCh* const qname,
const XERCES_CPP_NAMESPACE::Attributes& attrs
);
void endElement(const XMLCh* const uri,
const XMLCh* const localname,
const XMLCh* const qname
);
void characters(const XMLCh* const chars,
const XMLSize_t length
);
void fatalError(const xercesc::SAXParseException&);
};
CErrorHandler::CErrorHandler()
{
}
CErrorHandler::~CErrorHandler()
{
}
void CErrorHandler::startElement(const XMLCh* const uri,
const XMLCh* const localname,
const XMLCh* const qname,
const xercesc::Attributes& attrs)
{
char* name = xercesc::XMLString::transcode(localname);
std::cout << name;
xercesc::XMLString::release(&name);
}
void CErrorHandler::endElement(const XMLCh* const uri,
const XMLCh* const localname,
const XMLCh* const qname)
{
char* name = xercesc::XMLString::transcode(localname);
xercesc::XMLString::release(&name);
}
void CErrorHandler::fatalError(const xercesc::SAXParseException& exception)
{
char* message = xercesc::XMLString::transcode(exception.getMessage());
std::cout << "Error: " << message << " at line: " << exception.getLineNumber() << std::endl;
xercesc::XMLString::release(&message);
}
void CErrorHandler::characters(const XMLCh* const chars,
const XMLSize_t length
)
{
}
bool validateSchema()
{
std::string XSD_SHEMA ="<?xml version=\"1.0\" encoding=\"UTF-8\" ?>...";
try
{
xercesc::XMLPlatformUtils::Initialize();
}
catch (const XERCES_CPP_NAMESPACE::XMLException& toCatch)
{
char* message = xercesc::XMLString::transcode(toCatch.getMessage());
std::cout << "Error during initialization!" << std::endl;
std::cout << "Exception message is: " << message;
XERCES_CPP_NAMESPACE::XMLString::release(&message);
return false;
}
xercesc::SAX2XMLReader* parser = xercesc::XMLReaderFactory::createXMLReader();
parser->setFeature( xercesc::XMLUni::fgSAX2CoreValidation, true);
parser->setFeature( xercesc::XMLUni::fgSAX2CoreNameSpaces, true);
xercesc::DefaultHandler* defaultHandler = new CErrorHandler();
xercesc::ContentHandler* h = new CErrorHandler();
xercesc::MemBufInputSource mis(reinterpret_cast< const XMLByte* >(XSD_SHEMA.c_str() ), XSD_SHEMA.size (), "/schema.xsd");
xercesc::Wrapper4InputSource wmis (&mis, false);
parser->loadGrammar (&wmis, xercesc::Grammar::SchemaGrammarType, true);
parser->setFeature (xercesc::XMLUni::fgXercesUseCachedGrammarInParse, true);
void* id = (void*)("file:///schema.xsd");
parser->setProperty (xercesc::XMLUni::fgXercesSchemaExternalNoNameSpaceSchemaLocation, id);
parser->setContentHandler(h);
parser->setErrorHandler(defaultHandler);
try
{
parser->parse(mXMLFilePath.c_str());
}
catch (const xercesc::XMLException& toCatch)
{
char* message = xercesc::XMLString::transcode(toCatch.getMessage());
std::cout << "Exception message is: "<< message << std::endl;;
xercesc::XMLString::release(&message);
return false;
}
catch (const xercesc::SAXParseException& toCatch)
{
char* message = xercesc::XMLString::transcode(toCatch.getMessage());
std::cout << "Exception message is: " << message << std::endl;;
xercesc::XMLString::release(&message);
return false;
}
catch (...)
{
std::cout << "Unexpected Exception" ;
return false;
}
delete parser;
delete defaultHandler;
return true;
}
I am trying to validate xml file with path mXMLFilePath and xsd schema in string XSD_SHEMA in c++ with Xerces lib.
I created CErrorHandler class and initialized it, set schema nolocation parameter for not setting in xml path to schema.
It build`s, but not work. Have somebody any ideas?

Answer 1

The Xerces library (for both parsing and loading a grammar) can handle input sources (aka classes implementing the InputSource interface). MemBufInputSource would be the class for cases when something exists only in-memory.
XMLPlatformUtils::Initialize();
XercesDOMParser* domParser;
domParser = new XercesDOMParser();
char *str = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\r\n<xs:schema xmlns:xs=\"http://www.w3.org/2001/XMLSchema\" elementFormDefault=\"qualified\" attributeFormDefault=\"unqualified\"> \r\n </xs:schema>";
std::string strContent = str;
xercesc::MemBufInputSource pMemBufIS((XMLByte*)strContent.c_str(),
strContent.size(), "xsd");
if (domParser->loadGrammar(pMemBufIS, Grammar::SchemaGrammarType) == NULL)
{
fprintf(stderr, "couldn't load schema\n");
return false;
}
domParser->setValidationScheme(XercesDOMParser::Val_Auto);
domParser->setDoNamespaces(true);
domParser->setDoSchema(true);
domParser->setValidationConstraintFatal(true);
domParser->setExternalNoNamespaceSchemaLocation("C:\\User\\b.xsd");
domParser->setValidationConstraintFatal(true);
domParser->parse("file.xml");
if (domParser->getErrorCount() == 0)
printf("XML file validated against the schema successfully\n");
else
printf("XML file doesn't conform to the schema\n");

Answer 2

#include <xercesc/sax2/SAX2XMLReader.hpp>
#include <xercesc/sax2/XMLReaderFactory.hpp>
#include <xercesc/sax/ErrorHandler.hpp>
#include <xercesc/sax/SAXParseException.hpp>
#include <xercesc/validators/common/Grammar.hpp>
#include <xercesc/parsers/SAXParser.hpp>
#include <xercesc/framework/MemBufInputSource.hpp>
#include <xercesc/util/XMLString.hpp>
#include <string>
#include <iostream>
class CErrorHandler : public xercesc::ErrorHandler
{
public:
/** Warning message method */
void warning(const xercesc::SAXParseException& ex);
/** Error message method */
void error(const xercesc::SAXParseException& ex);
/** Fatal error message method */
void fatalError(const xercesc::SAXParseException& ex);
/** Errors resetter method */
void resetErrors();
private:
/** Based message reporter method */
void reportParseException(const xercesc::SAXParseException& ex);
};
void CErrorHandler::reportParseException(const xercesc::SAXParseException& ex)
{
char* message = xercesc::XMLString::transcode(ex.getMessage());
std::cout << message << " at line " << ex.getLineNumber() << " column " << ex.getColumnNumber() << std::endl;
xercesc::XMLString::release(&message);
}
void CErrorHandler::warning(const xercesc::SAXParseException& ex)
{
reportParseException(ex);
}
void CErrorHandler::error(const xercesc::SAXParseException& ex)
{
reportParseException(ex);
}
void CErrorHandler::fatalError(const xercesc::SAXParseException& ex)
{
reportParseException(ex);
}
void CErrorHandler::resetErrors()
{
}
class CXmlValidator
{
public:
/** Constructor method */
CXmlValidator();
/** Xml file setter method */
void setFilePath(const std::string &filePath);
/** Destructor method */
~CXmlValidator();
/** Xml file with schema validation method */
bool validateSchema();
private:
/** Xml file */
std::string mXMLFilePath;
};
CXmlValidator::CXmlValidator():
mXMLFilePath("")
{
}
CXmlValidator::~CXmlValidator()
{
}
void CXmlValidator::setFilePath(const std::string &filePath)
{
mXMLFilePath = filePath;
}
bool CXmlValidator::validateSchema()
{
std::cout << std::endl;
xercesc::XMLPlatformUtils::Initialize();
std::string xsdFile = "<?xml version=\"1.0\" encoding=\"UTF-8\" ?>...";
xercesc::SAX2XMLReader *parser = xercesc::XMLReaderFactory::createXMLReader();
xercesc::ErrorHandler *handler = new CErrorHandler();
xercesc::MemBufInputSource inMemorySchemaSource(reinterpret_cast<const XMLByte*>(xsdFile.c_str()), xsdFile.size (), "/schema.xsd");
parser->loadGrammar(inMemorySchemaSource, xercesc::Grammar::SchemaGrammarType, true);
parser->setFeature(xercesc::XMLUni::fgXercesUseCachedGrammarInParse, true);
parser->setFeature(xercesc::XMLUni::fgSAX2CoreValidation, true);
parser->setFeature(xercesc::XMLUni::fgSAX2CoreNameSpaces, true);
parser->setProperty(xercesc::XMLUni::fgXercesSchemaExternalNoNameSpaceSchemaLocation, const_cast<void*>(static_cast<const void*>("")));
parser->setErrorHandler(handler);
parser->parse("file.xml");
if (parser->getErrorCount() != 0)
{
std::cout << "ERROR: XML file '" << mXMLFilePath << "' not confirm to the schema" << std::endl;
return false;
}
else
{
return true;
}
}
Here is correct realizations of error handler and validator classes, if somebody will need them