simple problem trying to specify a unique attribute with XML schema

[smachin1000]

Hi All,

In the sample schema & document below, I'd like the attribute "name" to
be unique for all function elements under function_list. The tools I'm
using (XML Spy and xmllint) all validate the sample document and do not
pick up that the name is not unique.
Any clues as to what could be going wrong?

Thanks.

-----------------------------------------------------------------------------------------------------------------------------
function_list.xsd:
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified" attributeFormDefault="unqualified">
<xs:element name="function_list">
<xs:complexType>
<xs:sequence maxOccurs="unbounded">
<xs:element ref="function"/>
</xs:sequence>
</xs:complexType>
<xs:unique name="unique_fn_name">
<xs:selector xpath="function_list"/>
<xs:field xpath="@name"/>
</xs:unique>
</xs:element>
<xs:element name="function">
<xs:complexType>
<xs:attribute name="name" type="xs:string" use="required"/>
<!-- want the above attribute to be unique -->
</xs:complexType>
</xs:element>
</xs:schema>

-----------------------------------------------------------------------------------------------------------------------------
function_list.xml:

<?xml version="1.0" encoding="UTF-8"?>
<function_list xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="function_list.xsd">
<function name="fred"/>
<function name="fred"/>
<function name="frog"/>
<function name="fred"/>
</function_list>

 

[George Bina]

Hi,

Your unique constrint does not select any nodes because you are in a
function_list element and you select as selector all the cildren
elements that have the name function_list and there are no such
elements in your instance document

<xs:selector xpath="function_list"/>

What you want is probably

<xs:selector xpath="function"/>

Best Regards,
George

 

[smachin1000]

Thanks George,

Your advice worked
The other thing that was tripping me up is that my real world example
(as opposed to the canonical example I posted here) was using a default
namespace, so I had to some further tweaking to get the xpath expr. to
work correctly.