XmlSchemaUnique Class

 

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)


public class XmlSchemaUnique : XmlSchemaIdentityConstraint

NameDescription
System_CAPS_pubmethodXmlSchemaUnique()

Initializes a new instance of the XmlSchemaUnique class.

NameDescription
System_CAPS_pubpropertyAnnotation

Gets or sets the annotation property.(Inherited from XmlSchemaAnnotated.)

System_CAPS_pubpropertyFields

Gets the collection of fields that apply as children for the XML Path Language (XPath) expression selector.(Inherited from XmlSchemaIdentityConstraint.)

System_CAPS_pubpropertyId

Gets or sets the string id.(Inherited from XmlSchemaAnnotated.)

System_CAPS_pubpropertyLineNumber

Gets or sets the line number in the file to which the schema element refers.(Inherited from XmlSchemaObject.)

System_CAPS_pubpropertyLinePosition

Gets or sets the line position in the file to which the schema element refers.(Inherited from XmlSchemaObject.)

System_CAPS_pubpropertyName

Gets or sets the name of the identity constraint.(Inherited from XmlSchemaIdentityConstraint.)

System_CAPS_pubpropertyNamespaces

Gets or sets the XmlSerializerNamespaces to use with this schema object.(Inherited from XmlSchemaObject.)

System_CAPS_pubpropertyParent

Gets or sets the parent of this XmlSchemaObject.(Inherited from XmlSchemaObject.)

System_CAPS_pubpropertyQualifiedName

Gets the qualified name of the identity constraint, which holds the post-compilation value of the QualifiedName property.(Inherited from XmlSchemaIdentityConstraint.)

System_CAPS_pubpropertySelector

Gets or sets the XPath expression selector element.(Inherited from XmlSchemaIdentityConstraint.)

System_CAPS_pubpropertySourceUri

Gets or sets the source location for the file that loaded the schema.(Inherited from XmlSchemaObject.)

System_CAPS_pubpropertyUnhandledAttributes

Gets or sets the qualified attributes that do not belong to the current schema's target namespace.(Inherited from XmlSchemaAnnotated.)

NameDescription
System_CAPS_pubmethodEquals(Object)

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_protmethodFinalize()

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethodGetHashCode()

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_protmethodMemberwiseClone()

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

Specifies that an attribute or element value (or a combination of attribute or element values) must be unique within the specified scope. The constraint name must be unique within a schema.

The following example shows the use of the XmlSchemaUnique class.

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

class XMLSchemaExamples
{
    public static void Main()
    {

        XmlSchema schema = new XmlSchema();

        // <xs:complexType name="customerOrderType">
        XmlSchemaComplexType customerOrderType = new XmlSchemaComplexType();
        customerOrderType.Name = "customerOrderType";

        // <xs:sequence>
        XmlSchemaSequence sequence1 = new XmlSchemaSequence();

        // <xs:element name="item" minOccurs="0" maxOccurs="unbounded">
        XmlSchemaElement item = new XmlSchemaElement();
        item.MinOccurs = 0;
        item.MaxOccursString = "unbounded";
        item.Name = "item";

        // <xs:complexType>
        XmlSchemaComplexType ct1 = new XmlSchemaComplexType();

        // <xs:attribute name="itemID" type="xs:string"/>
        XmlSchemaAttribute itemID = 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"/>
        XmlSchemaAttribute CustomerID = 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">
        XmlSchemaElement ordersByCustomer = new XmlSchemaElement();
        ordersByCustomer.Name = "ordersByCustomer";

        // <xs:complexType>
        XmlSchemaComplexType ct2 = new XmlSchemaComplexType();

        // <xs:sequence>
        XmlSchemaSequence sequence2 = new XmlSchemaSequence();

        // <xs:element name="customerOrders" type="customerOrderType" minOccurs="0" maxOccurs="unbounded" />
        XmlSchemaElement customerOrders = 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">
        XmlSchemaUnique element_unique = new XmlSchemaUnique();
        element_unique.Name = "oneCustomerOrdersforEachCustomerID";

        // <xs:selector xpath="customerOrders"/>
        element_unique.Selector = new XmlSchemaXPath();
        element_unique.Selector.XPath = "customerOrders";

        // <xs:field xpath="@customerID"/>
        XmlSchemaXPath field = new XmlSchemaXPath();
        field.XPath = "@customerID";

        // </xs:unique>
        element_unique.Fields.Add(field);
        ordersByCustomer.Constraints.Add(element_unique);

        // </xs:element>
        schema.Items.Add(ordersByCustomer);

        XmlSchemaSet schemaSet = new XmlSchemaSet();
        schemaSet.ValidationEventHandler += new ValidationEventHandler(ValidationCallbackOne);
        schemaSet.Add(schema);
        schemaSet.Compile();

        XmlSchema compiledSchema = null;

        foreach (XmlSchema schema1 in schemaSet.Schemas())
        {
            compiledSchema = schema1;
        }

        XmlNamespaceManager nsmgr = new XmlNamespaceManager(new NameTable());
        nsmgr.AddNamespace("xs", "http://www.w3.org/2001/XMLSchema");
        compiledSchema.Write(Console.Out, nsmgr);
    }

    public static void ValidationCallbackOne(object sender, ValidationEventArgs args)
    {
        Console.WriteLine(args.Message);
    }
}

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>

.NET Framework
Available since 1.1

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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