Question

I’m trying to make up an xml schema for the following:

<tagSet>
  <Structure>
    <tag>
      <name>Steve</name>
    </tag>
    <tag>
      <name>Bob</name>
    </tag>
    <tag>
      <name>Steve</name>
    </tag>
  </Structure>
</tagSet>

I would like my schema to complain that Steve is there twice, but I can’t get it to work.

I have this under the tagSet element in the schema file:

<xs:key name="key" >
      <xs:selector xpath="Structure/tag" />
      <xs:field xpath="name" />
    </xs:key>

…but I clearly haven’t understood it right, as this is not working. Anyone spot my error?

Thanks 🙂

Answer 1

There is nothing incorrect about your xs:key definition. Have you properly referenced the XSD in your XML file?

I copied your XML data into a document:

<?xml version="1.0" encoding="utf-8" ?>
<tagSet xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:noNamespaceSchemaLocation="test.xsd">
  <Structure>
    <tag>
      <name>Steve</name>
    </tag>
    <tag>
      <name>Bob</name>
    </tag>
    <tag>
      <name>Steve</name>
    </tag>
  </Structure>
</tagSet>

Then I wrote a simple XSD with your xs:key included:

<?xml version="1.0" encoding="utf-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

  <xs:element name="tagSet">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="Structure" type="Structure-type" />
      </xs:sequence>
    </xs:complexType>

    <xs:key name="key">
      <xs:selector xpath="Structure/tag" />
      <xs:field xpath="name" />
    </xs:key>
  </xs:element>

  <xs:complexType name ="Structure-type">
    <xs:sequence>
      <xs:element name ="tag" type="tag-type" maxOccurs="unbounded" />
    </xs:sequence>
  </xs:complexType>

  <xs:complexType name="tag-type">
    <xs:sequence>
      <xs:element name="name" type="xs:string" />
    </xs:sequence>
  </xs:complexType>

</xs:schema>

And it complains about the duplicate key ‘Steve’ fine. If this example doesn’t help you find the problem, could you post more details about your schema and XML file?