No problem, I'm sure it will be quite useful for other readers. Will you
post the working schema?
Thanks,
Cezar
-Original Message-
From: Erik van Zijst [mailto:[EMAIL PROTECTED]
Sent: Friday, March 10, 2006 11:06 AM
To: user@xmlbeans.apache.org
Subject: Re: off-topic: substitutiongroups and inheritance
Nevermind, I think I solved it.
I missed the substitution group relation between the abstract types
and
the head. I just added substitutionGroup=shape to fgshape and
bgshape
and now it works.
I guess I just missed it as I was relying too much on inheritance. I
probably figured the hierarchy alone was enough for eraseShape to
accept cloud, as you would expect in OOP, so I didn't bother to
apply
them to the abstract types.
Thanks for being my rubber duck ;)
Erik
Erik van Zijst wrote:
Let me apologize in advance for the fact that this question is not
directly a xmlbeans issue. Instead, it's something I ran into
several
times while using xmlbeans. I know I'd better take it to a decent
xml
forum, but with all the expertise here, let me give it a try
nevertheless.
I'm having trouble translating my object inheritance models to
xmlschema
and have illustrated this in the attached example xsd and xml.
In my example I have a canvas for drawing a new painting and the xsd
contains the instructions for drawing this painting. According to
instructor Bob, a painting constists of two basic parts: background
and
foreground. An object is either a background or foreground object.
In the final stage, Bob removes objects that turned out ugly. This
can
be any type of object.
The schema defines an abstract type shape which fgshape and
gbshape
inherit from. It uses substitutiongroups with head shape.
drawBackground only accepts background shapes, drawForeground
only
accepts foreground shapes, while eraseShapes accepts everything.
The problem is that the painting as defined in painting.xml is not
valid
according to the schema, because eraseShapes expects an element of
type shape, rather than cloud or its substitutiongroup
fgshape.
The error xmlbeans gives is:
Validation error at line: 12: Expected element
'[EMAIL PROTECTED]://prutser.cx/schemas/painting' instead of
'[EMAIL PROTECTED]://prutser.cx/schemas/painting' here in element
[EMAIL PROTECTED]://prutser.cx/schemas/painting
In an OO programming language this is not a problem. Cloud extends
fgshape, while fgshape extends shape, so you'll have no problem
passing
a cloud instance to eraseShapes.
How does one tackle this problem? Am I using substitutionGroups
incorrectly? I do want to be able to use the names of the concrete
elements, rather than shape type=cloud color=white
cloudtype=cumulunimbus/ if that's possible.
Erik van Zijst
?xml version=1.0 encoding=UTF-8?
xs:schema xmlns:xs=http://www.w3.org/2001/XMLSchema;
targetNamespace=http://prutser.cx/schemas/painting;
xmlns=http://prutser.cx/schemas/painting;
xmlns:tns=http://prutser.cx/schemas/painting;
xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance;
xs:element name=painting
xs:complexType
xs:sequence
xs:element ref=drawBackground/
xs:element ref=drawForeground/
xs:element ref=eraseShapes/
/xs:sequence
/xs:complexType
/xs:element
xs:element name=drawBackground
xs:complexType
xs:sequence
xs:element ref=bgshape minOccurs=1
maxOccurs=unbounded/
/xs:sequence
/xs:complexType
/xs:element
xs:element name=drawForeground
xs:complexType
xs:sequence
xs:element ref=fgshape minOccurs=1
maxOccurs=unbounded/
/xs:sequence
/xs:complexType
/xs:element
xs:element name=eraseShapes
xs:complexType
xs:sequence
xs:element ref=shape minOccurs=1
maxOccurs=unbounded/
/xs:sequence
/xs:complexType
/xs:element
xs:element name=shape type=shape-type abstract=true/
xs:complexType name=shape-type abstract=true
xs:attribute name=color type=xs:string
use=required/
xs:attribute name=preferredBrush type=xs:string
use=optional/
/xs:complexType
xs:element name=bgshape type=bgshape-type abstract=true/
xs:complexType name=bgshape-type abstract=true
xs:complexContent
xs:extension base=shape-type/
/xs:complexContent
/xs:complexType
xs:element name=cloud type=cloud-type
substitutionGroup=bgshape
