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Re: Repeating elements with fixed attribute values

From: Andrew Welch <andrew.j.welch@gmail.com>
Date: Fri, 4 Jan 2008 15:40:57 +0000
Message-ID: <74a894af0801040740n261b0c2bh52653d3c0aac492@mail.gmail.com>
To: "King, Jeffrey (Mission Systems)" <Jeff.King@ngc.com>
Cc: xmlschema-dev@w3.org

On 04/01/2008, King, Jeffrey (Mission Systems) <Jeff.King@ngc.com> wrote:
> I have an xml document similar to this:
>
> <root>
>   <word name="one">
>     <field name="field1" number="1">any string here</field>
>     <field name="field2" number="2">any string here</field>
>     <field name="field3" number="3">any string here</field>
>     
>   </word>
>   <word name="two">
>     <field name="field4" number="4">any string here</field>
>     <field name="field5" number="5">any string here</field>
>     <field name="field6" number="6">any string here</field>
>     
>   </word>
> </root>
>
> The attributes have fixed values.  I am struggling to create a schema for
> this.

If you mean you want to ensure that @number="1" if @name="field1" and
so on, then that's a "co-occurrence constraint", which isn't possible
to define in XML Schema.

It will be possible in XML Schema 1.1 (check out Saxon's schema
processor), but in the mean time you'll need to do the check in
another language, like Schematron or RelaxNG.

If you're feeling brave you could do the check using xchecker - the
schema would look something like this (note the <xck:check> element):

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xmlns:xck="http://xchecker.sf.net/"
    elementFormDefault="qualified"
    attributeFormDefault="unqualified">

    <xs:annotation>
        <xs:appinfo>
            <xck:check>//field[@number eq translate(@name, 'field',
'')]</xck:check>
        </xs:appinfo>
    </xs:annotation>

    <xs:element name="root" type="root"/>
    <xs:element name="word" type="word"/>
    <xs:element name="field" type="field"/>

    <xs:complexType name="root">
        <xs:sequence>
            <xs:element ref="word" maxOccurs="unbounded"/>
        </xs:sequence>
    </xs:complexType>

    <xs:complexType name="word">
        <xs:sequence>
            <xs:element ref="field" maxOccurs="unbounded"/>
        </xs:sequence>
        <xs:attribute name="name" use="required" type="non-empty-string"/>
    </xs:complexType>

    <xs:complexType name="field">
        <xs:simpleContent>
            <xs:extension base="xs:string">
                <xs:attribute name="name" use="required"
type="non-empty-string"/>
                <xs:attribute name="number" use="required" type="xs:integer"/>
            </xs:extension>
        </xs:simpleContent>
    </xs:complexType>

    <xs:simpleType name="non-empty-string">
        <xs:restriction base="xs:string">
            <xs:minLength value="1"/>
        </xs:restriction>
    </xs:simpleType>   	

</xs:schema>


More here: http://xchecker.sourceforge.net/


cheers
-- 
Andrew Welch
http://andrewjwelch.com
Kernow: http://kernowforsaxon.sf.net/
Received on Friday, 4 January 2008 15:41:09 GMT

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