HOW TO: Use SAX to Validate XML Data in Visual C++ (311423)

SUMMARY

This step-by-step article describes how to use Simple API for XML (SAX) to validate XML data in Microsoft Visual C++.

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Discussion of the Saxxsdvalid.exe File

The following file is available for download from the Microsoft Download Center:
The Saxxsdvalid.exe file contains the following files:

File name	Size
Po.xml	1K
Po.xsd	3K
Saxerrorhandlerimpl.cpp	2K
Saxerrorhandlerimpl.h	2K
Saxxsd.cpp	2K
Saxxsd.dsp	5K
Saxxsd.dsw	1K
Saxxsderrorhandler.h	2K
Saxxsderrorhandler.cpp	2K
Stdafx.cpp	1K
Stdafx.h	2K

Saxxsdvalid.exe demonstrates how to use SAX to validate XML data with XSD schema and to receive all validation errors in Visual C++. This sample implements the ISAXErrorHandler interface to receive errors that the SAX reader generates.

Saxxsdvalid.exe does the following:

1. Creates a schema cache object and sets appropriate flags with the SAX reader in the main function, as follows:

               //Create the schema cache.
               IXMLDOMSchemaCollectionPtr pSchemaCache;
               CHR(pSchemaCache.CreateInstance(__uuidof(XMLSchemaCache40)));
   
               //Add a schema to the schema cache.
               CHR(pSchemaCache->add(L"http://www.example.org/po", _variant_t("po.xsd")));  
   
               //Turn on the validation feature.
               CHR(pReader->putFeature(L"schema-validation",VARIANT_TRUE));
   
               //Receive all validation errors.
               CHR(pReader->putFeature(L"exhaustive-errors", VARIANT_TRUE));
   
               //Associate the schema cache with the SAX reader.
               CHR(pReader->putProperty(L"schemas", _variant_t(pSchemaCache.GetInterfacePtr())));
   
   
   					

2. Outputs the error to the console window in the error event handler of the SAXXSDErrorHandler class, as follows:

        int m, n;
        HRESULT hr = pLocator->getLineNumber(&m);
        hr = pLocator->getColumnNumber(&n);
   
        wprintf(L"\n %ld \n line : %ld column : %ld\n  %s\n", hrErrorCode,m, n, pwchErrorMessage);
   
        printf("\n");
   
        // Return S_OK to continue the parsing.
        return S_OK;
   
   					

3. Outputs the fatal error in the fatal error event handler of the SAXXSDErrorHandler class, as follows:

        wprintf(L"\n fatal Error %ld \n line : %d column : %d\n  %s\n", hrErrorCode,pLocator->getLineNumber, pLocator->getColumnNumber, pwchErrorMessage);
   
        return hrErrorCode;
   					

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Use SAX to Validate XML Data

To use SAX to validate XML data, follow these steps:

1. Unzip the Saxxsdvalid.exe file.
2. Compile and run the application. Validation errors such as the following are printed on the console window:
   Parsing document: po.xml
   -2147467259
   line : 1 column : 79
   Required attribute 'confirmDate' is missing.
   
   -2147467259
   line : 29 column : 16
   Element content is invalid according to the DTD/Schema.
   Expecting: {http://www.example.org/po}comment.