"QName" Datatype Values and Representations

XSD Tutorials - Herong's Tutorial Examples

∟"QName" Datatype Values and Representations

This section describes the built-in primitive datatype, 'QName' that represents XML element and attribute names with or without namespaces. Leading and trailing whitespaces are allowed and trimmed.

"QName" is a built-in datatype that represents (namespace URI, local name) pairs used as XML element and attribute names with these rules:

The value space of "QName" is all (namespace URI, local name) pairs with "namespace URI" as optional.
The lexical space of "QName" is all possible "QName" values represented in /((namepspacePrefix):)?(localName)/ patten.
"namespacePrefix" part is optional. If exists, if must be defined to a URI.
"namespacePrefix" and "localName" must be valid "NCName" lexical representations.
Leading and trailing whitespaces allowed and trimmed.

To verify these rules, I wrote this simple XSD document that uses "QName" datatype to declare XML elements:

<?xml version="1.1"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<!-- QName_datatype_test.xsd
 - Copyright (c) 2002-2013 HerongYang.com. All Rights Reserved.
-->
<xs:element name="QName_Datatype_Test">
  <xs:complexType>
    <xs:sequence>
      <xs:element name="QName" type="xs:QName"
         maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>
</xs:element>
</xs:schema>

Here is a sample XML document that can be used to test these declarations:

<?xml version="1.1"?>
<!-- QName_datatype_test.xml
 - Copyright (c) 2002-2013 HerongYang.com. All Rights Reserved.
-->
<QName_Datatype_Test xmlns:hy="herongyang.com">

<!-- 3 valid "QName" elements -->
  <QName>    schema   </QName>
  <QName>    hy:Tutorial   </QName>
  <QName>    hy:&#x5934;   </QName>

<!-- 3 invalid "QName" elements -->
  <QName>    2ndOption   </QName>
  <QName>    xs:schema   </QName>
  <QName>    hy:hy:any   </QName>
</QName_Datatype_Test>

When validating this XML document with my XsdSchemaValidator.java program presented earlier in the book, I get 3 groups of errors for 3 invalid XML elements:

herong> java XsdSchemaValidator
^^^ QName_datatype_test.xsd QName_datatype_test.xml

Error:
   Line number: 13
   Column number: 34
   Message: cvc-datatype-valid.1.2.1: '2ndOption' is not a valid value
   for 'QName'. (Numeric digits not allowed as the leading character)

Error:
   Line number: 13
   Column number: 34
   Message: cvc-type.3.1.3: The value '    2ndOption   ' of element
   'QName' is not valid.

Error:
   Line number: 14
   Column number: 34
   Message: UndeclaredPrefix: Cannot resolve 'xs:schema' as a QName:
   the prefix 'xs' is not declared. ("xs" must be declared)

Error:
   Line number: 14
   Column number: 34
   Message: cvc-type.3.1.3: The value '    xs:schema   ' of element
   'QName' is not valid.

Error:
   Line number: 15
   Column number: 34
   Message: cvc-datatype-valid.1.2.1: 'hy:hy:any' is not a valid
   value for 'QName'. (Maximum 1 ":" allowed)

Error:
   Line number: 15
   Column number: 34
   Message: cvc-type.3.1.3: The value '    hy:hy:any   ' of element
   'QName' is not valid.

Failed with errors: 6