XmlSchemaSet Class

Reference

Definition

Namespace:: System.Xml.Schema

Assembly:: System.Xml.ReaderWriter.dll

Assembly:: System.Xml.dll

Assembly:: netstandard.dll

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Contains a cache of XML Schema definition language (XSD) schemas.

public ref class XmlSchemaSet

public class XmlSchemaSet

type XmlSchemaSet = class

Public Class XmlSchemaSet

Inheritance: Object
XmlSchemaSet

Examples

The following example validates an XML file using schemas stored in the XmlSchemaSet. The namespace in the XML file, urn:bookstore-schema, identifies which schema in the XmlSchemaSet to use for validation. Output from the example shows that the XML file has two schema violations:

The first <book> element contains an <author> element but no <title> or <price> element.
The <author> element in the last <book> element is missing a <first-name> and <last-name> element and instead has an invalid <name> element.

#using <System.Xml.dll>

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

// Display any validation errors.
static void ValidationCallBack( Object^ /*sender*/, ValidationEventArgs^ e )
{
   Console::WriteLine( L"Validation Error:\n   {0}", e->Message );
   Console::WriteLine();
}

int main()
{
   // Create the XmlSchemaSet class.
   XmlSchemaSet^ sc = gcnew XmlSchemaSet;

   // Add the schema to the collection.
   sc->Add( L"urn:bookstore-schema", L"books.xsd" );

   // Set the validation settings.
   XmlReaderSettings^ settings = gcnew XmlReaderSettings;
   settings->ValidationType = ValidationType::Schema;
   settings->Schemas = sc;
   settings->ValidationEventHandler += gcnew ValidationEventHandler(ValidationCallBack);

   // Create the XmlReader object.
   XmlReader^ reader = XmlReader::Create( L"booksSchemaFail.xml", settings );

   // Parse the file. 
   while ( reader->Read() )
      ;

   return 1;
}
// The example displays output like the following:
//   Validation Error: 
//        The element 'book' in namespace 'urn:bookstore-schema' has invalid child element 'author' 
//        in namespace 'urn:bookstore-schema'. List of possible elements expected: 'title' in 
//        namespace 'urn:bookstore-schema'.
//
//    Validation Error: 
//       The element 'author' in namespace 'urn:bookstore-schema' has invalid child element 'name' 
//       in namespace 'urn:bookstore-schema'. List of possible elements expected: 'first-name' in 
//       namespace 'urn:bookstore-schema'.

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

public class Sample
{
  public static void Main() {

    // Create the XmlSchemaSet class.
    XmlSchemaSet sc = new XmlSchemaSet();

    // Add the schema to the collection.
    sc.Add("urn:bookstore-schema", "books.xsd");

    // Set the validation settings.
    XmlReaderSettings settings = new XmlReaderSettings();
    settings.ValidationType = ValidationType.Schema;
    settings.Schemas = sc;
    settings.ValidationEventHandler += ValidationCallBack;

    // Create the XmlReader object.
    XmlReader reader = XmlReader.Create("booksSchemaFail.xml", settings);

    // Parse the file.
    while (reader.Read());
  }

  // Display any validation errors.
  private static void ValidationCallBack(object sender, ValidationEventArgs e) {
    Console.WriteLine($"Validation Error:\n   {e.Message}\n");
  }
}
// The example displays output like the following:
//   Validation Error:
//        The element 'book' in namespace 'urn:bookstore-schema' has invalid child element 'author'
//        in namespace 'urn:bookstore-schema'. List of possible elements expected: 'title' in
//        namespace 'urn:bookstore-schema'.
//
//    Validation Error:
//       The element 'author' in namespace 'urn:bookstore-schema' has invalid child element 'name'
//       in namespace 'urn:bookstore-schema'. List of possible elements expected: 'first-name' in
//       namespace 'urn:bookstore-schema'.

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

Public Module Sample 
  Public Sub Main() 

    ' Create the XmlSchemaSet class.
    Dim sc as XmlSchemaSet = new XmlSchemaSet()

    ' Add the schema to the collection.
    sc.Add("urn:bookstore-schema", "books.xsd")

    ' Set the validation settings.
    Dim settings as XmlReaderSettings = new XmlReaderSettings()
    settings.ValidationType = ValidationType.Schema
    settings.Schemas = sc
    AddHandler settings.ValidationEventHandler, AddressOf ValidationCallBack
 
    ' Create the XmlReader object.
    Dim reader as XmlReader = XmlReader.Create("booksSchemaFail.xml", settings)

    ' Parse the file. 
    While reader.Read()
    End While
    
  End Sub

  ' Display any validation errors.
  Private Sub ValidationCallBack(sender as object, e as ValidationEventArgs) 
    Console.WriteLine($"Validation Error:{vbCrLf}   {e.Message}")
    Console.WriteLine()
  End Sub
End Module
' The example displays output like the following:
'   Validation Error: 
'        The element 'book' in namespace 'urn:bookstore-schema' has invalid child element 'author' 
'        in namespace 'urn:bookstore-schema'. List of possible elements expected: 'title' in 
'        namespace 'urn:bookstore-schema'.
'
'    Validation Error: 
'       The element 'author' in namespace 'urn:bookstore-schema' has invalid child element 'name' 
'       in namespace 'urn:bookstore-schema'. List of possible elements expected: 'first-name' in 
'       namespace 'urn:bookstore-schema'.

Input

The sample uses the following two input files.

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>

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>

Remarks

Important

Do not use schemas from unknown or untrusted sources or locations. Doing so will compromise the security of your code.
XML schemas (including inline schemas) are inherently vulnerable to denial of service attacks; do not accept them in untrusted scenarios.
Schema validation error messages and exceptions may expose sensitive information about the content model or URI paths to the schema file. Be careful not to expose this information to untrusted callers.
Additional security considerations are covered in the "Security Considerations" section.

XmlSchemaSet is a cache or library where you can store XML Schema definition language (XSD) schemas. XmlSchemaSet improves performance by caching schemas in memory instead of accessing them from a file or a URL. Each schema is identified by the namespace URI and location that was specified when the schema was added to the set. You use the XmlReaderSettings.Schemas property to assign the XmlSchemaSet object an XML reader should use for data validation.

Security Considerations

Do not use schemas from unknown or untrusted sources. Doing so will compromise the security of your code. External namespaces or locations referenced in include, import, and redefine elements of a schema are resolved with respect to the base URI of the schema that includes or imports them. For example, if the base URI of the including or importing schema is empty or null, the external locations are resolved with respect to the current directory. The XmlUrlResolver class is used to resolve external schemas by default. To disable resolution of include, import, and redefine elements of a schema, set the XmlSchemaSet.XmlResolver property to null.
The XmlSchemaSet class uses the System.Text.RegularExpressions.Regex class to parse and match regular expressions in an XML schema. Validation of pattern facets with regular expressions in an XML schema may involve increased CPU usage and should be avoided in high availability scenarios.
Exceptions raised as a result of using the XmlSchemaSet class, such as the XmlSchemaException class may contain sensitive information that should not be exposed in untrusted scenarios. For example, the SourceUri property of an XmlSchemaException returns the URI path to the schema file that caused the exception. The SourceUri property should not be exposed in untrusted scenarios. Exceptions should be properly handled so that this sensitive information is not exposed in untrusted scenarios.

Constructors

XmlSchemaSet()	Initializes a new instance of the XmlSchemaSet class.
XmlSchemaSet(XmlNameTable)	Initializes a new instance of the XmlSchemaSet class with the specified XmlNameTable.

Properties

CompilationSettings	Gets or sets the XmlSchemaCompilationSettings for the XmlSchemaSet.
Count	Gets the number of logical XML Schema definition language (XSD) schemas in the XmlSchemaSet.
GlobalAttributes	Gets all the global attributes in all the XML Schema definition language (XSD) schemas in the XmlSchemaSet.
GlobalElements	Gets all the global elements in all the XML Schema definition language (XSD) schemas in the XmlSchemaSet.
GlobalTypes	Gets all of the global simple and complex types in all the XML Schema definition language (XSD) schemas in the XmlSchemaSet.
IsCompiled	Gets a value that indicates whether the XML Schema definition language (XSD) schemas in the XmlSchemaSet have been compiled.
NameTable	Gets the default XmlNameTable used by the XmlSchemaSet when loading new XML Schema definition language (XSD) schemas.
XmlResolver	Sets the XmlResolver used to resolve namespaces or locations referenced in include and import elements of a schema.

Methods

Add(String, String)	Adds the XML Schema definition language (XSD) schema at the URL specified to the XmlSchemaSet.
Add(String, XmlReader)	Adds the XML Schema definition language (XSD) schema contained in the XmlReader to the XmlSchemaSet.
Add(XmlSchema)	Adds the given XmlSchema to the XmlSchemaSet.
Add(XmlSchemaSet)	Adds all the XML Schema definition language (XSD) schemas in the given XmlSchemaSet to the XmlSchemaSet.
Compile()	Compiles the XML Schema definition language (XSD) schemas added to the XmlSchemaSet into one logical schema.
Contains(String)	Indicates whether an XML Schema definition language (XSD) schema with the specified target namespace URI is in the XmlSchemaSet.
Contains(XmlSchema)	Indicates whether the specified XML Schema definition language (XSD) XmlSchema object is in the XmlSchemaSet.
CopyTo(XmlSchema[], Int32)	Copies all the XmlSchema objects from the XmlSchemaSet to the given array, starting at the given index.
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetType()	Gets the Type of the current instance. (Inherited from Object)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
Remove(XmlSchema)	Removes the specified XML Schema definition language (XSD) schema from the XmlSchemaSet.
RemoveRecursive(XmlSchema)	Removes the specified XML Schema definition language (XSD) schema and all the schemas it imports from the XmlSchemaSet.
Reprocess(XmlSchema)	Reprocesses an XML Schema definition language (XSD) schema that already exists in the XmlSchemaSet.
Schemas()	Returns a collection of all the XML Schema definition language (XSD) schemas in the XmlSchemaSet.
Schemas(String)	Returns a collection of all the XML Schema definition language (XSD) schemas in the XmlSchemaSet that belong to the given namespace.
ToString()	Returns a string that represents the current object. (Inherited from Object)

Events

ValidationEventHandler

Specifies an event handler for receiving information about XML Schema definition language (XSD) schema validation errors.

Applies to