XML schema restriction to values of another element

[mruedy]

I would like to know if it is possible to write an XML Schema restriction that binds to values of another element.

For example I have XML

<people>
    <family name="Smith">
        <origin>England</origin>
    </family>
    <family name="Jain">
        <origin>India</origin>
    </family>
    <family name="DelSol">
        <origin>Spain</origin>
    </family>
    <person>
         <Given>Mary</Given>
         <Family>Smith</Family>
    </person>
    <person>
         <Given>Jorege</Given>
         <Family>DelSol</Family>
    </person>
    <person>
         <Given>Sundeep</Given>
         <Family>Jain</Family>
    </person>
    <person>
         <Given>John</Given>
         <Family>Farley</Family>
    </person>
</people>

In the following XML Schema I would like to restrict the Family value of a person to one of the name attributes of the family elements. This should complain on the last person as the Family name was not listed as a family element.

Is it possible to do so?

Thanks
Mark

<?xml version="1.0" encoding="utf-8"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="people">
    <xs:complexType>
      <xs:sequence>
        <xs:element maxOccurs="unbounded" name="family">
          <xs:complexType>
            <xs:sequence>
              <xs:element name="origin" type="xs:string" />
            </xs:sequence>
            <xs:attribute name="name" type="xs:string" use="required" />
          </xs:complexType>
        </xs:element>
        <xs:element maxOccurs="unbounded" name="person">
          <xs:complexType>
            <xs:sequence>
              <xs:element name="Given" type="xs:string" />
              <xs:element name="Family" type="xs:string" />
            </xs:sequence>
          </xs:complexType>
        </xs:element>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
</xs:schema>

[rski]

I'm afraid not in XML Schema. But you can define it in Schematron

[jkmyoung]

Yes you can, assuming no 2 family names are the same.

Put this at the end of your people node:

<xs:keyref name="familyNameRef" refer="familyName">
    <xs:selector xpath="person"/>
    <xs:field xpath="Family"/>
</xs:keyref>
<xs:key name="familyName">
    <xs:selector xpath="family"/>
    <xs:field xpath="@name"/>
</xs:key>
 

Your validator should throw an error like:
cvc-identity-constraint.4.3: Key 'familyNameRef' with value 'Farley' not found for identity constraint of element 'people'.

[mruedy]

@jkmyoung
jkmyoung,

With your snippet, I get this

~/family > xmllint --noout --schema people.xsd people.xml
Unimplemented block at xmlschemas.c:5588
Unimplemented block at xmlschemas.c:5588
people.xml validates
~/family >


I put the block just before the </xs:element> (end tag) for people. Is that the correct location? I am using:

~/family > xmllint --version
xmllint: using libxml version 20616
compiled with: DTDValid FTP HTTP HTML C14N Catalog XPath XPointer XInclude Iconv Unicode Regexps Automata Schemas
~/family >

Thanks

[jkmyoung]

I didn't know you were using xmllint. XML Schema support in libxml2 is quite incomplete.

I've heard there is a newer version of xmllint, but am not sure. Try:
http://www.xmlsoft.org/ to find an updated version.

[mruedy]

@jkmyoung
Is there a non-network based (local executable) validator that will work with this?