XmlSchemaUnique Class
.NET Framework 2.0
Represents the unique element from XML Schema as specified by the World Wide Web Consortium (W3C). This class can be used to identify a unique constraint among a set of elements.
Namespace: System.Xml.Schema
Assembly: System.Xml (in system.xml.dll)
Assembly: System.Xml (in system.xml.dll)
The following example shows the use of the XmlSchemaUnique class.
Imports System Imports System.Xml Imports System.Xml.Schema Class XMLSchemaExamples Public Shared Sub Main() Dim schema As New XmlSchema() ' <xs:complexType name="customerOrderType"> Dim customerOrderType As New XmlSchemaComplexType() customerOrderType.Name = "customerOrderType" ' <xs:sequence> Dim sequence1 As New XmlSchemaSequence() ' <xs:element name="item" minOccurs="0" maxOccurs="unbounded"> Dim item As New XmlSchemaElement() item.MinOccurs = 0 item.MaxOccursString = "unbounded" item.Name = "item" ' <xs:complexType> Dim ct1 As New XmlSchemaComplexType() ' <xs:attribute name="itemID" type="xs:string"/> Dim itemID As New XmlSchemaAttribute() itemID.Name = "itemID" itemID.SchemaTypeName = New XmlQualifiedName("string", "http://www.w3.org/2001/XMLSchema") ' </xs:complexType> ct1.Attributes.Add(itemID) ' </xs:element> item.SchemaType = ct1 ' </xs:sequence> sequence1.Items.Add(item) customerOrderType.Particle = sequence1 ' <xs:attribute name="CustomerID" type="xs:string"/> Dim CustomerID As New XmlSchemaAttribute() CustomerID.Name = "CustomerID" CustomerID.SchemaTypeName = New XmlQualifiedName("string", "http://www.w3.org/2001/XMLSchema") customerOrderType.Attributes.Add(CustomerID) ' </xs:complexType> schema.Items.Add(customerOrderType) ' <xs:element name="ordersByCustomer"> Dim ordersByCustomer As New XmlSchemaElement() ordersByCustomer.Name = "ordersByCustomer" ' <xs:complexType> Dim ct2 As New XmlSchemaComplexType() ' <xs:sequence> Dim sequence2 As New XmlSchemaSequence() ' <xs:element name="customerOrders" type="customerOrderType" minOccurs="0" maxOccurs="unbounded" /> Dim customerOrders As New XmlSchemaElement() customerOrders.MinOccurs = 0 customerOrders.MaxOccursString = "unbounded" customerOrders.Name = "customerOrders" customerOrders.SchemaTypeName = New XmlQualifiedName("customerOrderType", "") ' </xs:sequence> sequence2.Items.Add(customerOrders) ' </xs:complexType> ct2.Particle = sequence2 ordersByCustomer.SchemaType = ct2 ' <xs:unique name="oneCustomerOrdersforEachCustomerID"> Dim element_unique As New XmlSchemaUnique() element_unique.Name = "oneCustomerOrdersforEachCustomerID" ' <xs:selector xpath="customerOrders"/> element_unique.Selector = New XmlSchemaXPath() element_unique.Selector.XPath = "customerOrders" ' <xs:field xpath="@customerID"/> Dim field As New XmlSchemaXPath() field.XPath = "@customerID" ' </xs:unique> element_unique.Fields.Add(field) ordersByCustomer.Constraints.Add(element_unique) ' </xs:element> schema.Items.Add(ordersByCustomer) Dim schemaSet As New XmlSchemaSet() AddHandler schemaSet.ValidationEventHandler, AddressOf ValidationCallbackOne schemaSet.Add(schema) schemaSet.Compile() Dim compiledSchema As XmlSchema = Nothing For Each schema1 As XmlSchema In schemaSet.Schemas() compiledSchema = schema1 Next Dim nsmgr As New XmlNamespaceManager(New NameTable()) nsmgr.AddNamespace("xs", "http://www.w3.org/2001/XMLSchema") compiledSchema.Write(Console.Out, nsmgr) End Sub Public Shared Sub ValidationCallbackOne(ByVal sender As Object, ByVal args As ValidationEventArgs) Console.WriteLine(args.Message) End Sub End Class
The following XML file is generated for this code example.
<?xml version="1.0" encoding="IBM437"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:complexType name="customerOrderType"> <xs:sequence> <xs:element name="item" minOccurs="0" maxOccurs="unbounded"> <xs:complexType> <xs:attribute name="itemID" type="xs:string"/> </xs:complexType> </xs:element> </xs:sequence> <xs:attribute name="CustomerID" type="xs:string"/> </xs:complexType> <xs:element name="ordersByCustomer"> <xs:complexType> <xs:sequence> <xs:element name="customerOrders" type="customerOrderType" minOccurs="0" maxOccurs="unbounded" /> </xs:sequence> </xs:complexType> <xs:unique name="oneCustomerOrdersforEachCustomerID"> <xs:selector xpath="customerOrders"/> <xs:field xpath="@customerID"/> </xs:unique> </xs:element> </xs:schema>
System.Object
System.Xml.Schema.XmlSchemaObject
System.Xml.Schema.XmlSchemaAnnotated
System.Xml.Schema.XmlSchemaIdentityConstraint
System.Xml.Schema.XmlSchemaUnique
System.Xml.Schema.XmlSchemaObject
System.Xml.Schema.XmlSchemaAnnotated
System.Xml.Schema.XmlSchemaIdentityConstraint
System.Xml.Schema.XmlSchemaUnique
Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.
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