ComplexType Element Binding Support

This topic is specific to a legacy technology. XML Web services and XML Web service clients should now be created using Windows Communication Foundation.

The .NET Framework provides binding support for the <complexType> element.

The Xsd.exe tool equates XML Schema complex types with .NET Framework types whose public fields or properties represent the complex type's contents.

Explanation

The Xsd.exe tool equates XML Schema complex types with .NET Framework types whose public fields represent the complex type's contents.

Abstract Attribute

A complex type is declared abstract (abstract="true") to ensure that only instances of derived types, and not instances of the abstract base type, appear in a conformant XML document.

Xsd.exe equates an abstract complex type with an abstract class. The conversion works in both directions between code and XSD documents.

Aside from the use of the abstract keyword, the abstract class is treated like a non-abstract base class. Child classes extend the base class. Xsd.exe applies to the abstract class one System.Xml.Serialization.XmlIncludeAttribute for each descendant class. Each XmlInclude attribute specifies the type of the descendant class.

Example: Abstract Attribute

The following code example demonstrates using the abstract attribute with the <complexType> element.

Input XML Schema document:

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
         targetNamespace="http://example.org/" xmlns="http://example.org/" elementFormDefault="qualified">
  <xsd:element name="FamilyNode" type="FamilyNodeType" />
  <xsd:complexType name="FamilyNodeType">
    <xsd:sequence>
      <xsd:element name="Code" type="xsd:string" />
      <xsd:element name="Parent" type="Parent" />
    </xsd:sequence>
  </xsd:complexType>
  <xsd:complexType name="Daughter">
    <xsd:complexContent>
      <xsd:extension base="Parent">
        <xsd:sequence>
          <xsd:element name="Date" type="xsd:dateTime" minOccurs="0"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <xsd:complexType name="Son">
    <xsd:complexContent>
      <xsd:extension base="Parent">
        <xsd:sequence>
          <xsd:element name="Info" type="xsd:string" minOccurs="0"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  <xsd:complexType name="Parent" abstract="true">
    <xsd:sequence>
      <xsd:element name="Text" type="xsd:normalizedString" />
    </xsd:sequence>
  </xsd:complexType>
  <xsd:complexType name="Grandchild">
    <xsd:complexContent>
      <xsd:extension base="Daughter">
        <xsd:attribute name="Parent" type="xsd:normalizedString" />
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
</xsd:schema>

C# classes generated from the preceding XML Schema document:

[System.Xml.Serialization.XmlTypeAttribute(Namespace="http://example.org/")]
[System.Xml.Serialization.XmlRootAttribute("FamilyNode", Namespace="http://example.org/", IsNullable=false)]
public class FamilyNodeType {
        
    public string Code;
        
    public Parent Parent;
}
    
[System.Xml.Serialization.XmlTypeAttribute(Namespace="http://example.org/")]
[System.Xml.Serialization.XmlIncludeAttribute(typeof(Son))]
[System.Xml.Serialization.XmlIncludeAttribute(typeof(Daughter))]
[System.Xml.Serialization.XmlIncludeAttribute(typeof(Grandchild))]
public abstract class Parent {
    [System.Xml.Serialization.XmlElementAttribute(DataType="normalizedString")]
    public string Text;
}
    
[System.Xml.Serialization.XmlTypeAttribute(Namespace="http://example.org/")]
public class Son : Parent {        
    public string Info;
}
    
[System.Xml.Serialization.XmlTypeAttribute(Namespace="http://example.org/")]
[System.Xml.Serialization.XmlIncludeAttribute(typeof(Grandchild))]
public class Daughter : Parent {
        
    public System.DateTime Date;
        
    [System.Xml.Serialization.XmlIgnoreAttribute()]
    public bool DateSpecified;
}
    
 [System.Xml.Serialization.XmlTypeAttribute(Namespace="http://example.org/")]
public class Grandchild : Daughter {        
    [System.Xml.Serialization.XmlAttributeAttribute("Parent", DataType="normalizedString")]
    public string Parent1;
}

The XML schema generated from classes compiled from the preceding C# source code is effectively equivalent to the original XML schema.

Possible parent elements: <element>, <redefine>, <schema>

Possible child elements: <all>, <annotation>, <anyAttribute>, <attribute>, <attributeGroup>, <choice>, <complexContent>, <group>, <sequence>, <simpleContent>

See Also

Reference

XmlSchemaComplexType