XSD Tutorials - Herong's Tutorial Examples - v5.23, by Herong Yang
Nested Atomic and List Union Datatypes
This section provides a tutorial example on how atomic union and list union datatypes can be used as member datatypes to construct nested union datatypes.
Comparing to "list" construction component, "union" is more open. It can be nested on top of other atomic, list, atomic union and list union datatypes to build nested union datatypes.
For example, the following XSD document uses "union" components nested with a "union" or "list" sub component define 2 new simple datatypes:
<?xml version="1.1"?> <!-- nested_union_test.xsd - Copyright (c) 2002-2013 HerongYang.com. All Rights Reserved. --> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:simpleType name="mixedUnion"> <xs:union memberTypes="xs:time xs:NCName"/> </xs:simpleType> <xs:simpleType name="integerList"> <xs:list itemType="xs:integer"/> </xs:simpleType> <xs:element name="Nested_Union_Test"> <xs:complexType> <xs:sequence> <xs:element name="UnionOfList" maxOccurs="unbounded"> <!-- "union" of list and atomic datatypes --> <xs:simpleType> <xs:union memberTypes="integerList xs:NCName"/> </xs:simpleType> </xs:element> <xs:element name="UnionOfUnion" maxOccurs="unbounded"> <!-- "union" of union and list datatypes --> <xs:simpleType> <xs:union memberTypes="mixedUnion integerList"/> </xs:simpleType> </xs:element> </xs:sequence> </xs:complexType> </xs:element> </xs:schema>
Here is a sample XML document to test the above XSD document:
<?xml version="1.1"?> <!-- nested_union_test.xml - Copyright (c) 2002-2013 HerongYang.com. All Rights Reserved. --> <Nested_Union_Test> <!-- Valid "UnionOfList" list of 3 items --> <UnionOfList> 01 02 03 </UnionOfList> <UnionOfList> xsd </UnionOfList> <!-- Invalid "UnionOfList" values --> <UnionOfList> xsd schema </UnionOfList> <!-- Valid "UnionOfUnion" list values --> <UnionOfUnion> 01 02 03 </UnionOfUnion> <UnionOfUnion> 01:02:03 </UnionOfUnion> <UnionOfUnion> xsd </UnionOfUnion> <!-- Invalid "UnionOfUnion" values --> <UnionOfUnion> xsd:schema </UnionOfUnion> <UnionOfUnion> xsd schema </UnionOfUnion> </Nested_Union_Test>
When validating this XML document with my XsdSchemaValidator.java program presented earlier in the book, I get these errors:
herong> java XsdSchemaValidator ^^^ nested_union_test.xsd nested_union_test.xml Error: Line number: 12 Column number: 48 Message: cvc-datatype-valid.1.2.3: ' xsd schema ' is not a valid value of union type '#AnonType_UnionOfListNested_Union_Test'. Error: Line number: 12 Column number: 48 Message: cvc-type.3.1.3: The value ' xsd schema ' of element 'UnionOfList' is not valid. Error: Line number: 20 Column number: 46 Message: cvc-datatype-valid.1.2.3: ' xsd:schema ' is not a valid value of union type '#AnonType_UnionOfUnionNested_Union_Test'. Error: Line number: 20 Column number: 46 Message: cvc-type.3.1.3: The value ' xsd:schema ' of element 'UnionOfUnion' is not valid. Error: Line number: 21 Column number: 50 Message: cvc-datatype-valid.1.2.3: ' xsd schema ' is not a valid value of union type '#AnonType_UnionOfUnionNested_Union_Test'. Error: Line number: 21 Column number: 50 Message: cvc-type.3.1.3: The value ' xsd schema ' of element 'UnionOfUnion' is not valid. Failed with errors: 6
Table of Contents
XML Editor and Schema Processor - XMLPad
Java API for XML Processing - JAXP
JAXP - XML Schema (XSD) Validation
Xerces2 Java Parser - Java API of XML Parsers
Introduction of XSD Built-in Datatypes
"string" and Its Derived Datatypes
"decimal" and Its Derived Datatypes
"dateTime" and Its Related Datatypes
Miscellaneous Built-in Datatypes
Facets, Constraining Facets and Restriction Datatypes
►"simpleType" - Defining Your Own Simple Datatypes
"simpleType" Components - User-Defined Simple Datatypes
"simpleType" Components with "restriction" Child Components
"simpleType" Components with "union" Child Components
"simpleType" Components with "list" Child Components
Atomic, List, Atomic Union and List Union Datatypes
Constraining Facets on List Datatypes
Constraining Facets on Union Datatypes
Nested List Datatypes - Not Allowed
►Nested Atomic and List Union Datatypes
Identity-Constraints: unique, key and keyref
Assertion as Custom Validation Rules
XML Schema Location and Namespace in XML Documents
Overriding Element Types in XML Documents