XmlSchemaCollection.ValidationEventHandler Event

Definition

Namespace:

System.Xml.Schema

Assembly:

System.Xml.ReaderWriter.dll

Source:

XmlSchemaCollection.cs

Sets an event handler for receiving information about the XDR and XML schema validation errors.

public:
 event System::Xml::Schema::ValidationEventHandler ^ ValidationEventHandler;

public event System.Xml.Schema.ValidationEventHandler ValidationEventHandler;

member this.ValidationEventHandler : System.Xml.Schema.ValidationEventHandler 

Event Type

ValidationEventHandler

Examples

The following example shows how to set an event handler to handle invalid XML Schemas.

#using <System.Xml.dll>
#using <System.dll>

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

public ref class Sample
{
private:
   //Display the schema error information.
   static void ValidationCallBack( Object^ sender, ValidationEventArgs^ args )
   {
      Console::WriteLine( "Invalid XSD schema: {0}", args->Exception->Message );
   }

public:
   static void main()
   {
      // Create the schema collection.
      XmlSchemaCollection^ xsc = gcnew XmlSchemaCollection;

      //Set an event handler to manage invalid schemas.
      xsc->ValidationEventHandler += gcnew ValidationEventHandler( Sample::ValidationCallBack );

      //Add the schema to the collection.  
      xsc->Add( nullptr, "invalid.xsd" );
   }
};

int main()
{
   Sample::main();
}

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

public class Sample
{

  public static void Main (){

    //Create the schema collection.
    XmlSchemaCollection xsc = new XmlSchemaCollection();

    //Set an event handler to manage invalid schemas.
    xsc.ValidationEventHandler += new ValidationEventHandler (ValidationCallBack);

    //Add the schema to the collection.
    xsc.Add(null, "invalid.xsd");
  }

  //Display the schema error information.
  private static void ValidationCallBack (object sender, ValidationEventArgs args){
     Console.WriteLine("Invalid XSD schema: " + args.Exception.Message);
  }
}

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

public class Sample

  public shared sub Main ()
 
    'Create the schema collection.
    Dim xsc as XmlSchemaCollection = new XmlSchemaCollection()

    'Set an event handler to manage invalid schemas.
    AddHandler xsc.ValidationEventHandler, AddressOf ValidationCallBack

    'Add the schema to the collection.  
    xsc.Add(nothing, "invalid.xsd")

  end sub

  'Display the schema error information.
  Private shared sub ValidationCallBack (sender as object, args as ValidationEventArgs) 
     Console.WriteLine("Invalid XSD schema: " + args.Exception.Message)
  end sub

end class

The preceding example uses the file invalid.xsd as input.

<xsd:schema xmlns:xsd='http://www.w3.org/2001/XMLSchema' >
 <xsd:complexType name="personName">
        <xsd:sequence>
            <xsd:element name="title" minOccurs="0" maxOccurs="1"/>
            <xsd:element name="forename" minOccurs="0" maxOccurs="unbounded"/>
            <xsd:element name="surname"/>
        </xsd:sequence>
    </xsd:complexType>

   <xsd:complexType name="simpleName">
        <xsd:complexContent>
            <xsd:restriction base="personName">
                <xsd:sequence>
                    <xsd:element name="title" minOccurs="0" maxOccurs="0"/>
                    <xsd:element name="firstname" minOccurs="1" maxOccurs="1"/>
                    <xsd:element name="surname"/>
                </xsd:sequence>
            </xsd:restriction>
        </xsd:complexContent>
    </xsd:complexType>

</xsd:schema>

Remarks

These events occur when the schemas are added to the collection. If an event handler is not provided, an XmlSchemaException is thrown on any validation errors where the Severity is XmlSeverityType.Error. To specify an event handler, define a callback function and add it to the ValidationEventHandler.

Important

The XmlSchemaCollection class is obsolete in the .NET Framework version 2.0 and has been replaced by the XmlSchemaSet class.