XSD The

XSD The <anyAttribute> Element

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The <anyAttribute> element enables us to extend the XML document with attributes not specified by the schema!

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The <anyAttribute> Element

The <anyAttribute> element enables us to extend the XML document with attributes not specified by the schema.
The following example is a fragment from an XML schema called "family.xsd". It shows a declaration for the "person" element. By using the <anyAttribute> element we can add any number of attributes to the "person" element:

<xs:element name="person">

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

Now we want to extend the "person" element with a "eyecolor" attribute. In this case we can do so, even if the author of the schema above never declared any "eyecolor" attribute.
Look at this schema file, called "attribute.xsd":

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
targetNamespace="https://www.w3schools.com"
xmlns="https://www.w3schools.com"
elementFormDefault="qualified">

<xs:attribute name="eyecolor">
  <xs:simpleType>
    <xs:restriction base="xs:string">
      <xs:pattern value="blue|brown|green|grey"/>
    </xs:restriction>
  </xs:simpleType>
</xs:attribute>

</xs:schema>

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The XML file below (called "Myfamily.xml"), uses components from two different schemas; "family.xsd" and "attribute.xsd":

<?xml version="1.0" encoding="UTF-8"?>

<persons xmlns="http://www.microsoft.com"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:SchemaLocation="http://www.microsoft.com family.xsd
https://www.w3schools.com attribute.xsd">

<person eyecolor="green">
  <firstname>Hege</firstname>
  <lastname>Refsnes</lastname>
</person>

<person eyecolor="blue">
  <firstname>Stale</firstname>
  <lastname>Refsnes</lastname>
</person>

</persons>

The XML file above is valid because the schema "family.xsd" allows us to add an attribute to the "person" element.
The <any> and <anyAttribute> elements are used to make EXTENSIBLE documents! They allow documents to contain additional elements that are not declared in the main XML schema.

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