XDR Validation with XmlSchemaCollection

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")

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.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

        Public Shared Sub PrintTypeInfo(vr As XmlValidatingReader)
            If vr.SchemaType IsNot Nothing Then
                If TypeOf vr.SchemaType Is XmlSchemaDatatype Or TypeOf vr.SchemaType Is XmlSchemaSimpleType Then
                    Dim value As Object = vr.ReadTypedValue()
                    Console.WriteLine($"{vr.NodeType}({vr.Name},{value.GetType().Name}):{value}")
                End If
            End If
        End Sub

        Public Shared Sub ValidationHandler(sender As Object, args As ValidationEventArgs)
            Console.WriteLine("***Validation error")
            Console.WriteLine($"Severity:{args.Severity}")
            Console.WriteLine($"Message:{args.Message}")
        End Sub
    End Class
End Namespace

using System;
using System.IO;
using System.Xml;
using System.Xml.Schema;

namespace ValidationSample
{
    class Sample
    {
        public static void Main()
        {
            var tr = new XmlTextReader("HeadCount.xml");
            var 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($"{vr.NodeType}({vr.Name},{value.GetType().Name}):{value}");
                }
            }
        }

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

See also

• ValidationType
• XmlSchemaCollection Schema Compilation