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Re: Variation depending on attribute value

From: G. Ken Holman <gkholman@CraneSoftwrights.com>
Date: Mon, 04 Aug 2003 08:45:33 -0400
Message-Id: <5.2.0.9.0.20030804082638.00b63450@pop.storm.ca>
To: "Xmlschema-Dev" <xmlschema-dev@w3.org>

At 2003-08-04 13:17 +0200, Camilla Brenchley wrote:
>Given the below schema, is it possible to specify that if the attribute
>"Type" equals "Double" then the element "WithDoubleBed" is required, i.e.
>minOccurs="1", and if it equals "DoubleOneChild" then the element "ChildAge"
>is required?

This is a co-occurrence constraint and I believe it cannot be supported in 
W3C Schema (though it can be supported using RELAX-NG).  I'd like to be 
proven wrong, though, as it a common requirement and applications would be 
unencumbered with certain validation checking if it were available.

I hope this helps.

................. Ken

p.s. Here is the RELAX-NG schema:

T:\ftemp>type camilla.rnc
datatypes x = "http://www.w3.org/2001/XMLSchema-datatypes"

start = element TestRoom
    {
       element Room
       {
          (
             attribute Type { "Single" | "Double" }
           |
             (
                attribute Type { "DoubleOneChild" },
                element ChildAge { x:integer }
             )
          ),
          element WithDoubleBed { x:string }?
       }+
    }

# end of file

T:\ftemp>type camilla1.xml
<TestRoom>
   <Room Type="Single">
     <WithDoubleBed>Yes</WithDoubleBed>
   </Room>
   <Room Type="Double">
   </Room>
   <Room Type="DoubleOneChild">
     <ChildAge>3</ChildAge>
     <WithDoubleBed>Yes</WithDoubleBed>
   </Room>
   <Room Type="DoubleOneChild">
     <WithDoubleBed>Yes</WithDoubleBed>
   </Room>
   <Room Type="Double">
     <ChildAge>3</ChildAge>
   </Room>
</TestRoom>

T:\ftemp>jing -c camilla.rnc camilla1.xml
T:\ftemp\camilla1.xml:12: error: required elements missing
T:\ftemp\camilla1.xml:15: error: element "ChildAge" not allowed in this context

T:\ftemp>


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Received on Monday, 4 August 2003 09:21:49 GMT

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