<http://www/Documentation/W3C/www.w3.org/TR/xmlschema-2/index.html>I've
added pyxb-users to this discussion to increase visibility.
One conceptual problem is that an XML element is not a first-class object in
PyXB. An element is simply an association of a name and some other data
with a type. PyXB does not really support creating instances of elements.
What it supports is creating instances of a type.
If you have a schema the defines an element MyElement, when you invoke:
MyElement(x)
what you're really doing is invoking something like:
MyElement.typeDefinition().__init__(x, _element=MyElement)
which creates the instance of the underlying type, but records its origin as
being associated with the given element.
In your case, since AttributeValue is of type xs:anyType, for which there
are no real instances, what you want to do is something like:
v = xs.string('abc', _element=AttributeValue)
Then when you do:
v.toxml()
the context from the associated element will affect the formatting, and
you'll get:
<ns1:anything xmlns:ns1="urn:test" xmlns:ns2="
http://www.w3.org/2001/XMLSchema"; xmlns:xsi="
http://www.w3.org/2001/XMLSchema-instance";
xsi:type="ns2:string">foo</ns1:anything>
which can be cleaned up using BindingDOMSupport.DeclareNamespace.
(Note that for this to work, you'll need a patch to
http://sourceforge.net/apps/trac/pyxb/ticket/95, which is in development.)
In fact, it should be unnecessary to add the _element keyword to the
constructor if you intend to assign the value to an element with a
compatible type. If the value is of a consistent type, you can just use it.
This is what PyXB does normally. It causes problems in SAML2 because of its
declaration:
<element name="AttributeValue" type="anyType" nillable="true"/>
Although http://www.w3.org/TR/xmlschema-1/#xsi_type indicates how xsi:type
can convey the actual type of the content, doing so does not itself allow
xs:string to validate against xs:anyType. My earlier reading of the
specifications suggested that such elements should be declared as abstract,
and the validation is allowed through the use of substitution groups. In
this case, the problem is compounded because you're using an instance of a
simple type to match against a completely unconstrained type which is
normally assumed to be a complex type.
At any rate, I'm working on a patch that will address this and your
http://sourceforge.net/apps/trac/pyxb/ticket/94. You may need to switch to
using the development version of PyXB out of git to test it, as it takes
about a half-day's work just to go through the steps required to push out a
new PyXB version and I don't want to do that until I know things work.
I'll let you know when there's something to try.
Peter
On Wed, Nov 3, 2010 at 6:24 AM, Dieter Maurer <die...@handshake.de> wrote:
> Hello Peter,
>
>
> as you have supposed, the formerly reported problem went away
> after I have removed the old installation, cleanly reinstalled version
> 1.1.2
> and then recreated all bindings. Thank you!
>
>
> My next problem occurs with the binding of the SAML2 element
> "AttributeValue", defined by the schema fragment
> <element name="AttributeValue" type="anyType" nillable="true"/>
>
> Corresponding elements should look like
>
> <AttributeValue xsi:type="xs:string">abc</AttributeValue>
>
> But, I cannot yet create such elements from Python.
>
> I have tried:
>
> * AttributeValue('abc')
>
> * AttributeValue(pyxb.BIND('abc'))
>
> * AttributeValue(pyxb.binding.datatypes.string('abc'))
>
> The former two complain about a missing namespace,
> the latter creates:
>
> <AttributeValue><xs:string>abc</xs:string></AttributeValue>
>
> Can you give me a hint how to precisely control the creation
> of binding instances of "xs:anyType"?
>
>
>
> --
> Dieter
>
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