XML Schema (XSD) Validation with XmlSchemaSet

XML documents can be validated against an XML schema definition language (XSD) schema in an XmlSchemaSet.

Validating XML Documents

XML documents are validated by the Create method of the XmlReader class. To validate an XML document, construct an XmlReaderSettings object that contains an XML schema definition language (XSD) schema with which to validate the XML document.

Note

The System.Xml.Schema namespace contains extension methods that make it easy to validate an XML tree against an XSD file when using LINQ to XML. For more information on validating XML documents with LINQ to XML, see How to: Validate Using XSD.

An individual schema or a set of schemas (as an XmlSchemaSet) can be added to an XmlSchemaSet by passing either one as a parameter to the Add method of XmlSchemaSet. Note that when validating a document the target namespace of the document must match the target namespace of the schema in the schema set.

The following is an example XML document.

<bookstore xmlns="http://www.contoso.com/books">
  <book genre="autobiography" publicationdate="1981-03-22" ISBN="1-861003-11-0">
    <title>The Autobiography of Benjamin Franklin</title>
    <author>
      <first-name>Benjamin</first-name>
      <last-name>Franklin</last-name>
    </author>
    <price>8.99</price>
  </book>
  <book genre="novel" publicationdate="1967-11-17" ISBN="0-201-63361-2">
    <title>The Confidence Man</title>
    <author>
      <first-name>Herman</first-name>
      <last-name>Melville</last-name>
    </author>
    <price>11.99</price>
  </book>
  <book genre="philosophy" publicationdate="1991-02-15" ISBN="1-861001-57-6">
    <title>The Gorgias</title>
    <author>
      <name>Plato</name>
    </author>
    <price>9.99</price>
  </book>
</bookstore>

The following is the schema that validates the example XML document.

<?xml version="1.0" encoding="utf-8"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://www.contoso.com/books" xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:element name="bookstore">
        <xs:complexType>
            <xs:sequence>
                <xs:element maxOccurs="unbounded" name="book">
                    <xs:complexType>
                        <xs:sequence>
                            <xs:element name="title" type="xs:string" />
                            <xs:element name="author">
                                <xs:complexType>
                                    <xs:sequence>
                                        <xs:element minOccurs="0" name="name" type="xs:string" />
                                        <xs:element minOccurs="0" name="first-name" type="xs:string" />
                                        <xs:element minOccurs="0" name="last-name" type="xs:string" />
                                    </xs:sequence>
                                </xs:complexType>
                            </xs:element>
                            <xs:element name="price" type="xs:decimal" />
                        </xs:sequence>
                        <xs:attribute name="genre" type="xs:string" use="required" />
                        <xs:attribute name="publicationdate" type="xs:date" use="required" />
                        <xs:attribute name="ISBN" type="xs:string" use="required" />
                    </xs:complexType>
                </xs:element>
            </xs:sequence>
        </xs:complexType>
    </xs:element>
</xs:schema>

In the code example that follows, the schema above is added to the XmlSchemaSetSchemas property of the XmlReaderSettings object. The XmlReaderSettings object is passed as a parameter to the Create method of the XmlReader object, which validates the XML document above.

The ValidationType property of the XmlReaderSettings object is set to Schema to enforce validation of the XML document by the Create method of the XmlReader object. A ValidationEventHandler is added to the XmlReaderSettings object to handle any Warning or Error events raised by errors found during the validation process of both the XML document and the schema.

#using <System.Xml.dll>

using namespace System;
using namespace System::Xml;
using namespace System::Xml::Schema;

static void booksSettingsValidationEventHandler( Object^ /*sender*/, ValidationEventArgs^ e )
{
   if ( e->Severity == XmlSeverityType::Warning )
   {
      Console::Write( L"WARNING: " );
      Console::WriteLine( e->Message );
   }
   else
   if ( e->Severity == XmlSeverityType::Error )
   {
      Console::Write( L"ERROR: " );
      Console::WriteLine( e->Message );
   }
}

int main()
{
   XmlReaderSettings^ booksSettings = gcnew XmlReaderSettings;
   booksSettings->Schemas->Add( L"http://www.contoso.com/books", L"books.xsd" );
   booksSettings->ValidationType = ValidationType::Schema;
   booksSettings->ValidationEventHandler += gcnew ValidationEventHandler( booksSettingsValidationEventHandler );
   XmlReader^ books = XmlReader::Create( L"books.xml", booksSettings );
   while ( books->Read() )
   {}

   return 0;
}

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

class XmlSchemaSetExample
{
    static void Main()
    {
        XmlReaderSettings booksSettings = new XmlReaderSettings();
        booksSettings.Schemas.Add("http://www.contoso.com/books", "books.xsd");
        booksSettings.ValidationType = ValidationType.Schema;
        booksSettings.ValidationEventHandler += new ValidationEventHandler(booksSettingsValidationEventHandler);

        XmlReader books = XmlReader.Create("books.xml", booksSettings);

        while (books.Read()) { }
    }

    static void booksSettingsValidationEventHandler(object sender, ValidationEventArgs e)
    {
        if (e.Severity == XmlSeverityType.Warning)
        {
            Console.Write("WARNING: ");
            Console.WriteLine(e.Message);
        }
        else if (e.Severity == XmlSeverityType.Error)
        {
            Console.Write("ERROR: ");
            Console.WriteLine(e.Message);
        }
    }
}
Imports System
Imports System.Xml
Imports System.Xml.Schema

Class XmlSchemaSetExample

    Shared Sub Main()

        Dim booksSettings As XmlReaderSettings = New XmlReaderSettings()
        booksSettings.Schemas.Add("http://www.contoso.com/books", "books.xsd")
        booksSettings.ValidationType = ValidationType.Schema
        AddHandler booksSettings.ValidationEventHandler, New ValidationEventHandler(AddressOf booksSettingsValidationEventHandler)

        Dim books As XmlReader = XmlReader.Create("books.xml", booksSettings)

        While books.Read()

        End While

    End Sub

    Shared Sub booksSettingsValidationEventHandler(ByVal sender As Object, ByVal e As ValidationEventArgs)

        If e.Severity = XmlSeverityType.Warning Then
            Console.Write("WARNING: ")
            Console.WriteLine(e.Message)

        ElseIf e.Severity = XmlSeverityType.Error Then
            Console.Write("ERROR: ")
            Console.WriteLine(e.Message)
        End If

    End Sub

End Class

See Also

XmlSchemaSet for Schema Compilation
Working with XML Schemas