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Re: Help: XML Schema - any element with fixed type?

• From: Martin Gudgin <marting@d...>
• To: Risheng Lin <rlin@e...>, Jeff Lowery <jlowery@s...>,xml-dev@l...
• Date: Fri, 01 Jun 2001 21:01:20 +0100

I'm afraid what you are asking for is a kind of 'wildcard' that XML Schema
does not support. What you are saying is; 'I know what the type of this
thing will be, I just don't know what namespace name and local name it will
have'. I had a similar requirement a little while ago for a schema I was
writing. The closest you can get is, as Jeff points out, substitution groups
but that only allows you to say; 'I don't know exactly what the name will be
but I know it will be one of these...'

The only thing I can suggest is to tell your users what element name(s) to
use. They will have to use the correct element names for the content anyway
( unless you were planning on using this technique for every element ) so
why not the 'top-level' element too?

Martin Gudgin
DevelopMentor

----- Original Message -----
From: "Risheng Lin" <rlin@e...>
To: "Jeff Lowery" <jlowery@s...>; <xml-dev@l...>
Sent: Thursday, June 01, 2000 8:58 PM
Subject: RE: Help: XML Schema - any element with fixed type?


> Thank you for your reply.
>
> But I don't think substitution group works for my question.
>
> To use substitution group, I must know the name of the element to
> substitute in advance and specify them in the schema. The problem here is
> that I don't know what the name of the tag the user want to use. I want to
> let user freely choose the tag name, no matter it is <data1>, <data2>, or
> <myappdata>, <data2001> etc. - as long as the content model of the element
> ( here it is constrained by type in the schema ) is fixed. Of course, the
> user can include or import the schema and then define the substitution
> group for some element name, but it is much inconvenient to user.
Moreover,
> I prefer not to expose my schema definition to user, so that the user
> doesn't need to learn schema so as to use the application.
>
> Is it possible?
>
>
>
>
>
> At 11:29 AM 06/01/2001 -0700, Jeff Lowery wrote:
> >A substitution group will allow you to define a set of elements that are
> >replacable for another element. The substitutable elements need to be of
the
> >same type, or a derived type, of the element they're being substituted
for.
> >
> >If you want the type fixed, then you can use a 'final' type as the
target(?)
> >element type, then any substitute elements would have to be of that type,
> >also.
> >
> > > -----Original Message-----
> > > From: Risheng Lin [mailto:rlin@e...]
> > > Sent: Thursday, June 01, 2000 9:19 AM
> > > To: xml-dev@l...
> > > Subject: Help: XML Schema - any element with fixed type?
> > >
> > >
> > > Hi,
> > >
> > > Can any one tell me whether there is a way to design an xml
> > > schema such
> > > that it allows a user to define any kind of element but with
> > > fixed types?
> > > i.e. the element tag name can be freely chosen by the user as
> > > long as the
> > > user's data follows the type defined in xml schema?
> > >
> > > For example:
> > >
> > > I want the following xml to be validated:
> > >
> > > <data1>
> > >       <x />
> > >       <y />
> > > </data1>
> > >
> > >
> > > <data2>
> > >        <x/>
> > >        <y/>
> > >   <data2>
> > >
> > > Here <x/> <y/ > are the datatype defined in xml schema and it
> > > needs to be
> > > fixed - this can be easily defined in XML schema; but I want
> > > the data tag (
> > > here: data1 and data2 ) to be freely chosen by user and the
> > > document is
> > > still valid. How to design such schema?
> > >
> > > Note: it is different from <any>, and <anytype>.
> > >
> > > Any one can show my how to do it?
> > >
> > > Thanks in advance.
> > >
> > > Risheng
> > >
> > >
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