I am having a problem with defining an element with simple content that must match a pattern AND have attributes.

I have to use xs:extension on the xs:simpleContent to define attributes, and a xs:restriction on the xs:simpleContent to set my xs:pattern, but I can't seem to do both at the same time! Is this right? What am I doing wrong?

This is fine:
<xs:element name="FILE_COUNT" nillable="false">
  <xs:complexType>
    <xs:simpleContent>
      <xs:extension base="xs:string">
        <xs:attribute name="START_POS" type="xs:string" use="required" fixed="4"/>
      </xs:extension>
    </xs:simpleContent>
  </xs:complexType>
</xs:element>

And so is this:
<xs:element name="FILE_COUNT" nillable="false">
  <xs:simpleType>
    <xs:restriction base="xs:string">
      <xs:pattern value="[0-9]{6}"/>
    </xs:restriction>
  </xs:simpleType>
</xs:element>

But I need to do something like this..
<xs:element name="FILE_COUNT" nillable="false">
  <xs:complexType>
    <xs:simpleContent>
      <xs:restriction base="xs:string">
         <xs:pattern value="[0-9]{6}"/>
         <xs:attribute name="START_POS" type="xs:string" use="required" fixed="4"/>
      </xs:restriction>
    </xs:simpleContent>
  </xs:complexType>
</xs:element>

Can anyone help?
Thanks,
Nick

You need to do it in two steps (that is, define an intermediate type which you don't actually need): first an extension to add the attribute, then a restriction to restrict the content. Or vice versa.

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

Thanks for the prompt reply Michael!

Was this the sort of thing you had in mind?

<xs:simpleType name="file_count">
 <xs:restriction base="xs:string">
  <xs:pattern value="[0-9]{6}"/>
 </xs:restriction>
</xs:simpleType>

<xs:element name="file_count" nillable="false">
 <xs:complexType>
  <xs:simpleContent>
   <xs:extension base="file_count">
    <xs:attribute name="CLASS" type="xs:string" use="required" fixed="DDM"/>
   </xs:extension>
  </xs:simpleContent>
</xs:complexType>
</xs:element>

If so, that give me other headache of totally rewriting my stuff, as the schema is written programmatically from an Oracle table. :-)

Thanks for your help.
Nick

Yes, that's the idea.

I'm afraid headaches are a permanent fact of life when writing XML Schemas!



Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference