XDR Validation with XmlSchemaCollection

Article
10/17/2014

If the XML-Data Reduced (XDR) schema you are validating against is stored in the XmlSchemaCollection, it is associated with the namespace URI specified when the schema was added to the collection. XmlValidatingReader maps the namespace URI in the XML document to the schema that corresponds to that URI in the collection.

For example, if the root element of the XML document is <bookstore xmlns="urn:newbooks-schema">, when the schema is added to the XmlSchemaCollection it references the same namespace, as follows:

xsc.Add("urn:newbooks-schema", "newbooks.xdr")

The following code example creates an XmlValidatingReader that takes an XmlTextReader and adds an XDR schema, HeadCount.xdr, to the XmlSchemaCollection.

Imports System
Imports System.IO
Imports System.Xml
Imports System.Xml.Schema


Namespace ValidationSample
    
   Class Sample
      
      Public Shared Sub Main()
         Dim tr As New XmlTextReader("HeadCount.xml")
         Dim vr As New XmlValidatingReader(tr)
         
         vr.Schemas.Add("xdrHeadCount", "HeadCount.xdr")
         vr.ValidationType = ValidationType.XDR
         AddHandler vr.ValidationEventHandler, AddressOf ValidationHandler
         
         While vr.Read()
            PrintTypeInfo(vr)
            If vr.NodeType = XmlNodeType.Element Then
               While vr.MoveToNextAttribute()
                  PrintTypeInfo(vr)
               End While
            End If
         End While
         Console.WriteLine("Validation finished")
      End Sub
      ' Main
      
      
      Public Shared Sub PrintTypeInfo(vr As XmlValidatingReader)
         If Not (vr.SchemaType Is Nothing) Then
            If TypeOf vr.SchemaType Is XmlSchemaDatatype Or TypeOf vr.SchemaType Is XmlSchemaSimpleType Then
               Dim value As Object = vr.ReadTypedValue()
               Console.WriteLine("{0}({1},{2}):{3}", vr.NodeType, vr.Name, value.GetType().Name, value)
            End If
         End If
      End Sub
      ' PrintTypeInfo
      
      
      Public Shared Sub ValidationHandler(sender As Object, args As ValidationEventArgs)
         Console.WriteLine("***Validation error")
         Console.WriteLine("Severity:{0}", args.Severity)
         Console.WriteLine("Message:{0}", args.Message)
      End Sub
      ' ValidationHandler
   End Class
   ' Sample
End Namespace
' ValidationSample
[C#]
using System;
using System.IO;
using System.Xml;
using System.Xml.Schema;

namespace ValidationSample
{
   class Sample
   {
      public static void Main()
      {
         XmlTextReader tr = new XmlTextReader("HeadCount.xml");
         XmlValidatingReader vr = new XmlValidatingReader(tr);

         vr.Schemas.Add("xdrHeadCount", "HeadCount.xdr");
         vr.ValidationType = ValidationType.XDR;
         vr.ValidationEventHandler += new ValidationEventHandler (ValidationHandler);

         while(vr.Read())
         {
            PrintTypeInfo(vr);
            if(vr.NodeType == XmlNodeType.Element)
            {
               while(vr.MoveToNextAttribute())
                  PrintTypeInfo(vr);
            }
         }
         Console.WriteLine("Validation finished");
      }

      public static void PrintTypeInfo(XmlValidatingReader vr)
      {
         if(vr.SchemaType != null)
         {
            if(vr.SchemaType is XmlSchemaDatatype || vr.SchemaType is XmlSchemaSimpleType)
            {
               object value = vr.ReadTypedValue();
               Console.WriteLine("{0}({1},{2}):{3}", vr.NodeType, vr.Name, value.GetType().Name, value);
            }
         }
      }

      public static void ValidationHandler(object sender, ValidationEventArgs args)
      {
         Console.WriteLine("***Validation error");
         Console.WriteLine("\tSeverity:{0}", args.Severity);
         Console.WriteLine("\tMessage:{0}", args.Message);
      }
   }
}

The following outlines the contents of the input file, HeadCount.xml, to be validated.

<!--Load HeadCount.xdr in SchemaCollection for Validation-->
<HeadCount xmlns='xdrHeadCount'>
   <Name>Waldo Pepper</Name>
   <Name>Red Pepper</Name>
</HeadCount>

The following outlines the contents of the XDR schema file, HeadCount.xdr, to be validated against.

<Schema xmlns="urn:schemas-microsoft-com:xml-data" xmlns:dt="urn:schemas-microsoft-com:datatypes">
   <ElementType name="Name" content="textOnly"/>
   <AttributeType name="Bldg" default="2"/>
   <ElementType name="HeadCount" content="eltOnly">
      <element type="Name"/>
      <attribute type="Bldg"/>
   </ElementType>
</Schema>

Share via

XDR Validation with XmlSchemaCollection

See Also

Additional resources