Re: [pyxb-users] Parsing with multiple namespaces

[Jon S. <js...@co...>]

  Thanks for the reply. I'll try to explain with an example below, and 
any help you can give would be much appreciated.

I generate the bindings like this:

$ pyxbgen -u shape.xsd -m shape
$ pyxbgen -u circle.xsd -m circle

Now the following code works (using the circle package):

from pyxb.utils import domutils
from circle import CreateFromDOM
p = CreateFromDOM(domutils.StringToDOM(open("example.xml").read()))

But this doesn't (using the shape package)

from pyxb.utils import domutils
from shape import CreateFromDOM
p = CreateFromDOM(domutils.StringToDOM(open("example.xml").read()))

Now in this case I could just use circle, but what if I add circle, 
pentagon, etc?
Because these are extensions I can't run pyxbgen on them all at once, and
because they're in different namespaces I shouldn't have to.

example.xml:

<?xml version="1.0"?>
<picture xmlns="http://www.example.com/shape"
          xmlns:c="http://www.example.com/circle">
<name>Example Picture</name>
<shapes>
<square>
<size>5</size>
</square>
<c:circle>
<c:radius>10</c:radius>
</c:circle>
</shapes>
</picture>


shape.xsd:

<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
   targetNamespace="http://www.example.com/shape"
   xmlns="http://www.example.com/shape"
   elementFormDefault="qualified">

<xs:element name="picture">
<xs:complexType>
<xs:sequence>
<xs:element name="name" type="xs:string"/>
<xs:element name="shapes" type="ShapesType"/>
</xs:sequence>
</xs:complexType>
</xs:element>

<xs:complexType name="ShapesType">
<xs:sequence>
<xs:element ref="shape" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>

<xs:element name="shape" type="ShapeType"/>
<xs:complexType name="ShapeType"/>

<xs:element name="square" substitutionGroup="shape">
<xs:complexType>
<xs:complexContent>
<xs:extension base="ShapeType">
<xs:sequence>
<xs:element name="size" type="xs:int"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
</xs:element>

</xs:schema>

circle.xsd:

<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
   xmlns:shp="http://www.example.com/shape"
   targetNamespace="http://www.example.com/circle"
   xmlns="http://www.example.com/circle"
   elementFormDefault="qualified">
<xs:import namespace="http://www.example.com/shape" 
schemaLocation="shape.xsd"/>

<xs:element name="circle" substitutionGroup="shp:shape">
<xs:complexType>
<xs:complexContent>
<xs:extension base="shp:ShapeType">
<xs:sequence>
<xs:element name="radius" type="xs:int"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
</xs:element>
</xs:schema>


Thanks again, Sorry for the long post.

Jon

On 22/02/11 14:17, Peter Bigot wrote:
> It's been a while since I've done anything with PyXB, so I may be 
> rusty.  But what you're describing is supposed to just work.
>
> PyXB maintains a registry of known namespaces, which is initialized 
> when a module is loaded.  As a document is processed, the relevant 
> namespace should be resolved and its content model used.
>
> Although each module contains helper functions CreateFromDocument and 
> CreateFromDOM, these should only provide a default namespace.  You 
> should be able to process a document that has full namespace 
> information by using any of the CreateFromDOM functions.  (The 
> document must include the necessary xmlns:foo="uri" namespace 
> declarations to map the namespace qualifiers to the actual namespaces 
> which are URIs.)
>
> If the document uses an absent namespace, then you have to use the 
> CreateFromDOM function from the correct module, or identify the 
> correct Namespace instance and provide it.  (These functions also 
> provide the option of overriding the default namespace, though I see a 
> potential bug in that CreateFromDocument ignores it in favor of the 
> module namespace.)
>
> I thought I had some multiple namespace examples in the manual, but I 
> don't see them offhand.  From the distribution, examples/xsdprimer 
> shows an example of a document that uses multiple namespaces, as would 
> anything involving the OGC schema.
>
> If you continue to have problems, please provide a pointer to a set of 
> example schema and a document, along with the application code that 
> isn't doing what you think it should, and I'll take a look.
>
> Peter
>
> On Tue, Feb 22, 2011 at 6:19 AM, Jon Siddle <js...@co... 
> <mailto:js...@co...>> wrote:
>
>     I'm looking at using pyxb for providing an extension mechanism and
>     could
>     do with some guidance.
>
>     Say I have a.xsd which provides a namespace containing the head of a
>     substitution group, and b.xsd which provides a separate namespace
>     and contains elements which can be substituted.
>
>     I can generate module a and module b, and I can successfully parse an
>     xml file using b.CreateFromDOM but not a.CreateFromDOM.
>
>     My problem is that b.xsd (and later c.xsd) will be introduced long
>     after
>     a.xsd. So once I've added c.xsd (module c), how do
>     I process a file which contains substitutions from both b and c?
>
>     I don't think this is specific to substitution groups at all. More
>     generally, if I have an XML file containing multiple namespaces;
>     how do
>     I parse
>     it?
>
>     Jon
>
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