RE: [xml-dev] Element as value of another Element

["Michael Kay" <mike@saxonica.com>]

If I understand correctly you want to allow things such as


<a>asdfgh</a>

<a><b>oihvcg</b></a>

In XML Schema 1.1 you can do this by defining the content model as mixed
content, and then constraining it with an assertion:

<xs:complexType>
  <xs:complexContent mixed="true">
     <xs:sequence>
       <xs:element name="b" minOccurs="0" maxOccurs="1"/>
     </xs:sequence>
  </xs:complexContent>
  <xs:assert select="exists(text()) ne exists(b)"/>
</xs:complexType>

Doing it with conditional type assignment would be nicer in many ways: you
really want to say that the type is either the simpleType xs:string or a
complexType that only allows a <b> child - but conditional type assignment
can only be driven from attribute values, so that's not possible here.

Michael Kay
http://www.saxonica.com/
 

> -----Original Message-----
> From: G. Ken Holman [mailto:gkholman@CraneSoftwrights.com] 
> Sent: 15 January 2008 17:29
> To: xml-dev@lists.xml.org
> Subject: Re: [xml-dev] Element as value of another Element
> 
> At 2008-01-15 07:50 -0800, Shashank Gupta wrote:
> >I want to define an element of type string such that it's 
> value can be 
> >either of :
> >-any string
> >-value of another element of type string
> >
> >I am using Schema.
> 
> Using W3C Schema 1.0 you cannot express that as a constraint.
> 
> >Something like :
> ><xs:simpleType name="a" value = any string OR another 
> element b of type 
> >string>
> 
> Using the ISO/IEC 19757-3 Schematron assertion-based 
> constraint language you can express your desired constraint, 
> but it is run separately from W3C Schema.
> 
> Off hand I'm not sure if the future W3C Schema 1.1 can help 
> in this regard ... I suspect that it can since it supports 
> co-occurrence constraints, but I don't know if there are limits.
> 
> I hope this helps.
> 
> . . . . . . . . . . . . . Ken
> 
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