Setting unique element restriction

tombliboo · February 12th, 2011, 06:29 AM

Here is my schema, what I'm unable to do is set unique restrictions on the title element.

Code:

<?xml version="1.0" encoding="ISO-8859-1"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
	<xs:element name="departments">
		<xs:complexType>
			<xs:sequence>
				<xs:element ref="department" minOccurs="1" maxOccurs="unbounded"/>
			</xs:sequence>
		</xs:complexType>
	</xs:element>
	<xs:element name="department">
		<xs:complexType>
			<xs:sequence>
				<xs:element ref="title" minOccurs="1" maxOccurs="1"/>
				<xs:element ref="subdepartment" minOccurs="1" maxOccurs="unbounded"/>
			</xs:sequence>
		</xs:complexType>
	</xs:element>
	<xs:element name="title">
		<xs:simpleType>
			<xs:restriction base="xs:string"/>
		</xs:simpleType>
	</xs:element>
	<xs:element name="subdepartment">
		<xs:simpleType>
			<xs:restriction base="xs:string"/>
		</xs:simpleType>
	</xs:element>
</xs:schema>

What I'm trying is this within the title element tag, XMLSpy accepts it as valid but the restriction does not work if I test duplicate titles in my XML.

Code:

<xs:unique name="testUnique">
	<xs:selector xpath="department"/>
	<xs:field xpath="title"/>
</xs:unique>

Please help!

Martin Honnen · February 12th, 2011, 06:40 AM

Put your xs: unique into the definition of the "departments" element:

Code:

<xs:element name="departments">
  <xs:complexType>...</xs:complexType>
  <xs:unique ...>...</xs:unique>
</xs:element>

tombliboo · February 12th, 2011, 02:14 PM

Thanks this works for "title" as a single element under "department". Another element under "department" is "subdepartment" and this is repeated 5 times for different sub departments.

If I try to enforce these to me unique, XMLSpy returns an error stating:

- Field '{anonymous}' of identity constraint 'UniqueSubDept' evaluates to a node-set with more than one member.

- Error location: departments / department / subdepartment

Here is the code:

Code:

<xs:unique name="UniqueSubDept">
	<xs:selector xpath="department"/>
             <xs:field xpath="subdepartment"/>
</xs:unique>

Please can you let me know how to enforce unique values within repeating elements?

Thanks

mhkay · February 12th, 2011, 03:35 PM

The general formula is like this: suppose you want every X within a Y to have a unique value for Z (for example, every employee within a company to have a unique works number, or every figure within a chapter to have a unique caption). Then the xs:unique declaration goes in the Y element; the xs:selector is path expression that selects all the X elements starting from the Y, and the xs:field is a path expression that selects the Z element or attribute (and there must only be one) starting from the X.

Now, I don't think I have fully understood your data or your requirement, but it looks to me something like

Code:

<xs:element name="departments">
  <xs:unique ...>
     <xs:selector xpath="department | department//subdepartment"/>
      <xs:field xpath="title"/>