Paul Everitt wrote:
> Stefan Behnel wrote:
>> Anyway, I don't know if it's a good idea to use XSLT here, since there
>> may be too many 'ifs' and 'maybes'.
>
> Ahh, too bad. I was hoping to avoid an approach that only worked with
> lxml. But, if that's the way it is, that's the way it is. Out of
> curiosity, is it not a good idea based on the current state, or the
> long-term plans as well?
As I said, if you want to test it, feel free. That way, we know what works and
what may have to be fixed. It may enable us to decide if it's worth
implementing.
> Essentially, I'm looking for a way to bring new nodes into a document.
> Similar to how XInclude does, but under programmatic control, and with the
> ability to do arguments.
XSLT supports arguments in functions, just like XPath does.
> I'd prefer to keep the integration point in a declarative document-oriented
> style, instead of a script-oriented style. But it sounds like I might not
> be able to get there from here and I have to take what I can get. :^)
>
>> But using element classes, you could do something like this (untested):
>>
>> ---------------------------
>> class MyDataFiller(ElementBase):
>> def _init(self):
>> child = self[0]
>> if child.tag == 'sqlquery':
>> query = child.text
>> del self[0] # remove sqlquery element to prevent running this
>> twice
>> # run SQL query, generate result child nodes for it
>>
>> Namespace('ns')['mydata'] = MyDataFiller
>>
>> xml = XML("""
>> <myroot xmlns='ns'>
>> <mydata>
>> <sqlquery>SELECT from ...</sqlquery>
>> </mydata>
>> </myroot>
>> """)
>>
>> data = xml[0] # will call _init()
>> for data_child in data:
>> # do something with data
>> ---------------------------
>
> In the example above, is the _init called when the document is parsed,
> or when the element is traversed?
I updated the documentation regarding this point, but for a short answer:
> Stated differently, if I want to evaluate the query and get the new
> nodes, do I have to write some script to grab each node and "evaluate" it?
Yes. This is only done when a Python object is instantiated. Which means that
you may have to do something like this:
tree.xpath('//XPath expression to find all complex elements')
to instantiate them first.
Stefan
|
