XmlValidatingReader.Schemas Property

 

Gets a XmlSchemaCollection to use for validation.

Namespace:   System.Xml
Assembly:  System.Xml (in System.Xml.dll)

Public ReadOnly Property Schemas As XmlSchemaCollection

Property Value

Type: System.Xml.Schema.XmlSchemaCollection

The XmlSchemaCollection to use for validation.

System_CAPS_noteNote

The XmlValidatingReader class is obsolete in .NET Framework 2.0. You can create a validating XmlReader instance by using the XmlReaderSettings class and the Create method. For more information, see the Remarks section of the XmlReader reference page.

The XmlSchemaCollection holds pre-loaded XML-Data Reduced (XDR) and XML Schema definition language (XSD) schemas. This property gives the reader access to the cache of schemas and allows it to validate without having to re-load schemas every time. The reader does not add anything to the XmlSchemaCollection.

If the XmlSchemaCollection includes an XML schema (XSD) which contains include or import elements that reference other namespaces, the schemas for these other namespaces are loaded for validation purposes only. Unless these schemas were explicitly added to the schema collection, they will not be accessible using any of the collection methods or properties. For example, if the collection contains the schema file a.xsd, which contains a reference to the schema file b.xsd, you must add b.xsd to the schema collection before you can access it using any of the collection methods or properties.

When the XmlSchemaCollection is accessed using the Schemas property, the XmlSchemaCollection.Add method uses the XmlResolver specified by the XmlValidatingReader.XmlResolver property.

System_CAPS_noteNote

The schemas must be added to the XmlSchemaCollection before the first Read call.

The following example validates three XML files using schemas stored in the XmlSchemaCollection.

Option Strict
Option Explicit

Imports System
Imports System.IO
Imports System.Xml
Imports System.Xml.Schema
Imports Microsoft.VisualBasic

Public Class SchemaCollectionSample
    Private doc1 As String = "booksSchema.xml"
    Private doc2 As String = "booksSchemaFail.xml"
    Private doc3 As String = "newbooks.xml"
    Private schema As String = "books.xsd"
    Private schema1 As String = "schema1.xdr"

    Private reader As XmlTextReader = Nothing
    Private vreader As XmlValidatingReader = Nothing
    Private m_success As Boolean = True

    Public Sub New()

            'Load the schema collection
            Dim xsc As New XmlSchemaCollection()
            xsc.Add("urn:bookstore-schema", schema) 'XSD schema
            xsc.Add("urn:newbooks-schema", schema1) 'XDR schema

            'Validate the files using schemas stored in the collection.
            Validate(doc1, xsc) 'Should pass.
            Validate(doc2, xsc) 'Should fail.   
            Validate(doc3, xsc) 'Should fail. 

    End Sub 'NewNew

    Public Shared Sub Main()
        Dim validation As New SchemaCollectionSample()
    End Sub 'Main

    Private Sub Validate(filename As String, xsc As XmlSchemaCollection)

            m_success = True
            Console.WriteLine()
            Console.WriteLine("Validating XML file {0}...", filename.ToString())
            reader = New XmlTextReader(filename)

            'Create a validating reader.
            vreader = New XmlValidatingReader(reader)

            'Use the schemas stored in the schema collection.
            vreader.Schemas.Add(xsc)

            'Set the validation event handler.
            AddHandler vreader.ValidationEventHandler, AddressOf ValidationCallBack
            'Read and validate the XML data.
            While vreader.Read()
            End While
            Console.WriteLine("Validation finished. Validation {0}", IIf(m_success, "successful", "failed"))
            Console.WriteLine()

            'Close the reader.
            vreader.Close()

    End Sub 'Validate


    Private Sub ValidationCallBack(sender As Object, args As ValidationEventArgs)
        m_success = False

        Console.Write((ControlChars.CrLf & ControlChars.Tab & "Validation error: " & args.Message))
    End Sub 'ValidationCallBack 
End Class 'SchemaCollectionSample

The sample uses the following five input files:

booksSchema.xml


<?xml version='1.0'?>
 <bookstore xmlns="urn:bookstore-schema">
   <book genre="autobiography">
     <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">
     <title>The Confidence Man</title>
     <author>
       <first-name>Herman</first-name>
       <last-name>Melville</last-name>
     </author>
     <price>11.99</price>
   </book>
 </bookstore>

booksSchemaFail.xml


<?xml version='1.0'?>
 <bookstore xmlns="urn:bookstore-schema">
   <book>
     <author>
       <first-name>Benjamin</first-name>
       <last-name>Franklin</last-name>
     </author>
   </book>
   <book genre="novel">
     <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">
     <title>The Gorgias</title>
     <author>
       <name>Plato</name>
     </author>
     <price>9.99</price>
   </book>
 </bookstore>

newbooks.xml


<?xml version='1.0'?>
<bookstore xmlns="urn:newbooks-schema">
  <book genre="novel" style="hardcover">
    <title>The Handmaid's Tale</title>
    <author>
      <first-name>Margaret</first-name>
      <last-name>Atwood</last-name>
    </author>
    <price>19.95</price>
  </book>
  <book genre="novel" style="other">
    <title>The Poisonwood Bible</title>
    <author>
      <first-name>Barbara</first-name>
      <last-name>Kingsolver</last-name>
    </author>
    <price>11.99</price>
  </book>
</bookstore>

books.xsd


<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
     xmlns="urn:bookstore-schema"
     elementFormDefault="qualified"
     targetNamespace="urn:bookstore-schema">

  <xsd:element name="bookstore" type="bookstoreType"/>

  <xsd:complexType name="bookstoreType">
   <xsd:sequence maxOccurs="unbounded">
    <xsd:element name="book"  type="bookType"/>
   </xsd:sequence>
  </xsd:complexType>

  <xsd:complexType name="bookType">
   <xsd:sequence>
    <xsd:element name="title" type="xsd:string"/>
    <xsd:element name="author" type="authorName"/>
    <xsd:element name="price"  type="xsd:decimal"/>
   </xsd:sequence>
   <xsd:attribute name="genre" type="xsd:string"/>
  </xsd:complexType>

  <xsd:complexType name="authorName">
   <xsd:sequence>
    <xsd:element name="first-name"  type="xsd:string"/>
    <xsd:element name="last-name" type="xsd:string"/>
   </xsd:sequence>
  </xsd:complexType>

 </xsd:schema>

schema1.xdr


<?xml version="1.0"?>
<Schema xmlns="urn:schemas-microsoft-com:xml-data"
        xmlns:dt="urn:schemas-microsoft-com:datatypes">
  <ElementType name="first-name" content="textOnly"/>
  <ElementType name="last-name" content="textOnly"/>
  <ElementType name="name" content="textOnly"/>
  <ElementType name="price" content="textOnly" dt:type="fixed.14.4"/>
  <ElementType name="author" content="eltOnly" order="one">
    <group order="seq">
      <element type="name"/>
    </group>
    <group order="seq">
      <element type="first-name"/>
      <element type="last-name"/>
    </group>
  </ElementType>
  <ElementType name="title" content="textOnly"/>
  <AttributeType name="genre" dt:type="string"/>
  <AttributeType name="style" dt:type="enumeration"
        dt:values="paperback hardcover"/>
  <ElementType name="book" content="eltOnly">
    <attribute type="genre" required="yes"/>
    <attribute type="style" required="yes"/>
    <element type="title"/>
    <element type="author"/>
    <element type="price"/>
  </ElementType>
  <ElementType name="bookstore" content="eltOnly">
    <element type="book"/>
  </ElementType>
</Schema>

.NET Framework
Available since 1.1
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