Quoting Terry Brown:
> Hi, new to generateDS and wondering if it can help with this. I want
> to develop an XML authoring system which shows the user a list of valid
> options based on an XML Schema.
>
> I've done this once before, long ago, used XSLT to translate the XSD to
> an XML "template" that a PHP web app. used to offer the user valid
> choices for adding elements etc. The speed was marginal, so I
> translated the whole thing to C++, which was no faster :-}
>
> This time my from scratch approach would be to use Python / lxml to
> generate a JSON serializable data structure for the "template", and
> Python / Django for the app. interface.
>
> But I'm wondering if generateDS or some of its components can handle
> the XSD -> "template" step. The member_data_items_ member is a step in
> the right direction, but doesn't have enough detail for min/maxOccurs,
> choice vs. sequence etc. etc.
>
> Is there a point where I can tap in to generateDS to answer the
> question: at node /some/node/path the valid attributes are ... and the
> valid elements are ...? With min/maxOccurs and other structure /
> constraint info. available.
Terry,
The kind of data mining task that you describe might be a complex
kind of thing to do with data bindings (classes) generated by
generateDS.py. You'd still have the problem of searching though the
tree to find the class you are looking for.
I've just recently been working on an extension to generateDS.py
itself that required a similar kind of search of an XML schema.
With the xpath capability in lxml, that seemed pretty easy. So, for
example, here is a small bit of code that searches for a complexType
with a specific name, and then retrieves all the attributes defined
in that complexType:
from lxml import etree
def test(infilename, typename):
root = etree.parse(infilename).getroot()
ns = {root.prefix: root.nsmap[root.prefix]}
pat = './/xs:complexType[@name="%s"]' % (typename, )
t1 = root.xpath(pat, namespaces=ns)[0]
attributes = t1.xpath('./xs:attribute', namespaces=ns)
for attribute_node in attributes:
# do something with each attribute node.
attr_name = attribute_node.get('name')
attr_type = attribute_node.get('type')
print 'attribute -- name: "%s" type: %s' % (attr_name,
attr_type, )
test('my_schema.xsd', typename="someDefinedType")
If I understand your need correctly, some of it at least seems quite
easy to do with lxml and xpath, as, perhaps, the above sample code
shows.
Hope this helps.
But, you are right. I certainly should experiment some with
generating data bindings from the XML schema that defines XML schema
itself. If I learn more about that, I'll let you know.
Dave
--
Dave Kuhlman
http://www.davekuhlman.org
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