The code below explains the process of creating an XML Document
from an XML file on the local system.
Listing 1
//Physical path of the XML File
string XmlFilePath = @"C:\NewXMLFile.xml";
//Physical path of the XSD File
string XSDFilePath = @"C:\NewXMLFile.xsd";
XmlDocument ObjXmlDocument = new XmlDocument();
try
{
ObjXmlDocument.Load(XmlFilePath);
}
catch (XmlException ObjXMLException)
{
MessageBox.Show("Not a Well Formed XML Document"+ ObjXMLException.Message);
}
return ObjXmlDocument;As shown in Listing 1 an object of type XMLDocument is
created and loaded with the XML file specified by the XmlFilePath variable. If
it is not a valid XML file, the XML exception is raised. A validation message
is shown to the user stating that the XML file given is not a valid XML file. Once
we know that the XML is a valid document we need to validate it against the XML
schema.
The code below explains loading the XSD file and creating a
validation event handler for it.
Listing 2
// Load the schema definition
XmlReaderSettings ObjXMLSettings = new XmlReaderSettings ();
ObjXMLSettings.ValidationType = ValidationType.Schema;
ObjXMLSettings.ValidationEventHandler +=
new System.Xml.Schema.ValidationEventHandler (ObjXMLSettings_ValidationEventHandler);
ObjXMLSettings.Schemas.Add (null, XmlReader.Create (XSDFilePath));
XMLReaderSettings - This class is new in the .NET Framework
version 2.0. This class specifies a set of features to support the XmlReader object
created by the Create method. As
shown in Listing 2, we instantiate the class and set the validation type. We
also add a validation event handler. The next listing will describe more about
the event handler.
The code below explains the validation event handler that
will be fired if the XML document does not match the XSD file.
Listing 3
private void ObjXMLSettings_ValidationEventHandler(object sender, ValidationEventArgs args)
{
if (args.Severity == XmlSeverityType.Error)
{
ErrorMessage.Append(args.Message);
}
}The code shown below is the actual statement that fires the
validation part.
Listing 4
XmlNodeReader ObjXmlNodeReader = new XmlNodeReader(ObjXmlDocument);
ObjXMLReader = XmlReader.Create (ObjXmlNodeReader, ObjXMLSettings);
// If there XML file does not match the XSD file
//then Validation event handler is fired in this statement
while (ObjXMLReader.Read ())
{
}
if(!String.IsNullOrEmpty(ErrorMessage.ToString()))
{
MessageBox.Show(ErrorMessage.ToString());
}As shown in the Listing 4 the object of XMLReader’s method
Read is fired. The error message which is populated by validation errors is
shown to the user if there are any.
