Re: [xml-dev] schema key/keyRef question - matching multiple keys

[Doug Marttila <doug@visual-io.com>]

I wanted to follow up with a full solution to the subID/license plate 
problem (albeit a more redundant solution than I was hoping for - oh well).

Below is sample xml and an xsd. The xsd has a number of uniques and 
key/keyRef pairs that should prevent incorrect sub id matchings.

Seems like people on this list are certainly aware of this solution - 
but, figured I'd just finish off the thread.

zip here containing both files...

http://www.visual-io.com/dougXsdSample/xsdSubIDsExample.zip

cheers,

doug

XML...

<subIDsForProjects xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"; 
xsi:noNamespaceSchemaLocation="subIDs.xsd">
   <meta>
       <var name="String" vID="1">
           <buckets>
               <bucket bID="1" name="High" vID="1"/>
               <bucket bID="2" name="Medium" vID="1"/>
               <bucket bID="3" name="Low" vID="1"/>
           </buckets>
       </var>
       <var name="String" vID="2">
           <buckets>
               <bucket bID="1" name="Top" vID="2"/>
               <bucket bID="13" name="Bottom" vID="2"/>
           </buckets>
       </var>
   </meta>
   <projects>
       <project name="Project 1">
           <vars>
               <var vID="1" bID="2"/>
               <var vID="2" bID="1"/>
           </vars>
       </project>
       <project name="Project 2">
           <vars>
               <var vID="1" bID="1"/>
               <var vID="2" bID="13"/>
           </vars>
       </project>
   </projects>
</subIDsForProjects>


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="subIDsForProjects">
       <xs:annotation>
           <xs:documentation>Simple example showing key/keyRefs for 
creating "chained" key refs - doug marttila, 
doug@visual-io.com</xs:documentation>
       </xs:annotation>
       <xs:complexType>
           <xs:sequence>
               <xs:element name="meta">
                   <xs:complexType>
                       <xs:sequence>
                           <xs:element name="var" maxOccurs="unbounded">
                               <xs:complexType>
                                   <xs:sequence>
                                       <xs:element name="buckets">
                                           <xs:complexType>
                                               <xs:sequence>
                                                   <xs:element 
name="bucket" maxOccurs="unbounded">
                                                       <xs:complexType>
                                                           
<xs:attribute name="name" type="xs:string" use="required"/>
                                                           
<xs:attribute name="vID" type="xs:nonNegativeInteger" use="required"/>
                                                           
<xs:attribute name="bID" type="xs:nonNegativeInteger" use="required"/>
                                                       </xs:complexType>
                                                   </xs:element>
                                               </xs:sequence>
                                           </xs:complexType>
                                           <xs:unique name="bIDMetaUnique">
                                               <xs:selector 
xpath="./bucket"/>
                                               <xs:field xpath="@bID"/>
                                           </xs:unique>
                                       </xs:element>
                                   </xs:sequence>
                                   <xs:attribute name="vID" 
type="xs:nonNegativeInteger" use="required"/>
                                   <xs:attribute name="name" 
type="xs:string" use="required"/>
                               </xs:complexType>
                               <xs:key name="IDKey">
                                   <xs:selector xpath="."/>
                                   <xs:field xpath="@vID"/>
                               </xs:key>
                               <xs:keyref name="IDKeyRef" refer="IDKey">
                                   <xs:selector xpath="./buckets/bucket"/>
                                   <xs:field xpath="@vID"/>
                               </xs:keyref>
                           </xs:element>
                       </xs:sequence>
                   </xs:complexType>
                   <xs:unique name="uniqueID">
                       <xs:selector xpath="./var"/>
                       <xs:field xpath="@vID"/>
                   </xs:unique>
               </xs:element>
               <xs:element name="projects">
                   <xs:complexType>
                       <xs:sequence>
                           <xs:element name="project" 
maxOccurs="unbounded">
                               <xs:complexType>
                                   <xs:sequence>
                                       <xs:element name="vars">
                                           <xs:complexType>
                                               <xs:sequence>
                                                   <xs:element 
name="var" maxOccurs="unbounded">
                                                       <xs:complexType>
                                                           
<xs:attribute name="vID" type="xs:nonNegativeInteger" use="required"/>
                                                           
<xs:attribute name="bID" type="xs:nonNegativeInteger" use="required"/>
                                                       </xs:complexType>
                                                   </xs:element>
                                               </xs:sequence>
                                           </xs:complexType>
                                           <xs:unique 
name="varIDUniqueProject">
                                               <xs:selector xpath="./var"/>
                                               <xs:field xpath="@vID"/>
                                           </xs:unique>
                                       </xs:element>
                                   </xs:sequence>
                                   <xs:attribute name="name" 
type="xs:string" use="required"/>
                               </xs:complexType>
                           </xs:element>
                       </xs:sequence>
                   </xs:complexType>
               </xs:element>
           </xs:sequence>
       </xs:complexType>
       <xs:key name="IDPairKey">
           <xs:selector xpath="./meta/var/buckets/bucket"/>
           <xs:field xpath="@bID"/>
           <xs:field xpath="@vID"/>
       </xs:key>
       <xs:keyref name="IDPairKeyRef" refer="IDPairKey">
           <xs:selector xpath="./projects/project/vars/var"/>
           <xs:field xpath="@bID"/>
           <xs:field xpath="@vID"/>
       </xs:keyref>
       <xs:key name="IDMetaProjectKey">
           <xs:selector xpath="./meta/var"/>
           <xs:field xpath="@vID"/>
       </xs:key>
       <xs:keyref name="IDMetaProjectKeyRef" refer="IDMetaProjectKey">
           <xs:selector xpath="./projects/project/vars/var"/>
           <xs:field xpath="@vID"/>
       </xs:keyref>
   </xs:element>
</xs:schema>



Henry S. Thompson wrote:
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> Doug Marttila writes:
>
>   
> > I am using a node in my xml to define variables. The defined variables
> > are referenced by ID in another node (a project). The problem is that
> > some variables have sub-ids (the variables are "buckets" instead of
> > numeric values, they can have values like "high" "med" "low")
> >     
>
> This is, I'm sorry to say, a Frequently Requested Feature, i.e. there
> is no simple way to achieve what you want.
>
> I think of this as the licence-plate problem -- cars have licence
> plates, which specify state and plate number.  Within states, plate
> numbers are unique.  Presuming a set of States keyed by @code, each
> containing a sequence of IssuedPlates keyed by @number, to check an
> ObservedPlate with @state and @number we need a _chained_ KeyRef,
> i.e. use @state to identify a State, then use @number to identify an
> IssuedPlate _within that State_.
>
> The work-around you suggest (as it were, copying @code down from State
> onto all IssuedPlates) is the only one I'm aware of.
>
> ht
> - -- 
>  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
>                      Half-time member of W3C Team
>     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
>             Fax: (44) 131 650-4587, e-mail: ht@inf.ed.ac.uk
>                    URL: http://www.ltg.ed.ac.uk/~ht/
> [mail really from me _always_ has this .sig -- mail without it is forged spam]
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