XSD - <anyAttribute>

<xs:anyAttribute> element is used to extend the XSD functionality. It is used to extend a complexType element defined in one xsd by an attribute which is not defined in the schema.

Consider an example − person.xsd has defined person complexType element. attributes.xsd has defined age attribute.

person.xsd

<?xml version = "1.0" encoding = "UTF-8"?>
<xs:schema xmlns:xs = "http://www.w3.org/2001/XMLSchema"
   targetNamespace = "http://www.tutorialspoint.com"
   xmlns = "http://www.tutorialspoint.com"
   elementFormDefault = "qualified">

   <xs:element name = "person">
      <xs:complexType >
         <xs:sequence>
            <xs:element name = "firstname" type = "xs:string"/>
            <xs:element name = "lastname" type = "xs:string"/>
            <xs:element name = "nickname" type = "xs:string"/>     
         </xs:sequence>
      </xs:complexType>
   </xs:element>
	
</xs:schema>

attributes.xsd

<?xml version = "1.0" encoding = "UTF-8"?>
<xs:schema xmlns:xs = "http://www.w3.org/2001/XMLSchema"
   targetNamespace = "http://www.tutorialspoint.com"
   xmlns = "http://www.tutorialspoint.com"
   elementFormDefault = "qualified">

   <xs:attribute name = "age">
      <xs:simpleType>
         <xs:restriction base = "xs:integer">
            <xs:pattern value = "[0-100]"/>
         </xs:restriction>
      </xs:simpleType>
   </xs:attribute>
	
</xs:schema>

If we want to define a person with age in XML, then the following declaration will be invalid.

person.xml

<?xml version = "1.0"?>
<class xmlns = "http://www.tutorialspoint.com"
   xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation = "http://www.tutorialspoint.com person.xsd
   http://www.tutorialspoint.com attributes.xsd">  

   <person age = "20">
      <firstname>Dinkar</firstname>
      <lastname>Kad</lastname>
      <nickname>Dinkar</nickname>  
   </person>
	
</class>

Use <xs:anyAttribute>

In order to validate above person.xml, add <xs:anyAttribute> to person element in person.xsd.

person.xsd

<?xml version = "1.0" encoding = "UTF-8"?>
<xs:schema xmlns:xs = "http://www.w3.org/2001/XMLSchema"
   targetNamespace = "http://www.tutorialspoint.com"
   xmlns = "http://www.tutorialspoint.com"
   elementFormDefault = "qualified">

   <xs:element name = "person">
      <xs:complexType >
         <xs:sequence>
            <xs:element name = "firstname" type = "xs:string"/>
            <xs:element name = "lastname" type = "xs:string"/>
            <xs:element name = "nickname" type = "xs:string"/>            
         </xs:sequence>
         <xs:anyAttribute/>
      </xs:complexType>
   </xs:element>

</xs:schema>

Now person.xml will be validated against person.xsd and attributes.xsd.