DOM / XPath combination

[Phoebian]

Hi all,

Here is a little concept problem, and I need some guideline. I am currently developing a application which delivers XML files. I want then to sequentially perform some actions on selected part of that XML file through a XPath expression. These action have actually to modify the structure of the XML file itself and that seems to me like a big hurdle. Maybe I am wrong but I will try to explain what I want to do...

the XML file ressembles that... very roughly

<Root>
<Obj1>
<Head action="yes">blah</Head>
<Body>blah</Body>
<Foot action="yes">blah</Foot>
</Obj1>
...
<Obj2>
<Head>blah</Head>
<Body action="yes">blah</Body>
<Foot>blah</Foot>
</Obj2>
</Root>

let say my XPath expression is '//*[@action="yes"]'. Now for each of the 3 concerned element I want to do some formatting...

<Root>
<Obj1>
<Head action="yes">
<bonus>yo</bonus> <--- added as part of the formatting <text>blah<text> <--- formatting </Head> <Body>blah</Body> <Foot action="yes"> <text>blah<text> <--- formatting <bonus>yo</bonus> <--- added as part of the formatting </Foot> </Obj1> ... <Obj2> <Head>blah</Head> <Body action="yes"> <text>blah<text> <--- formatting </Body> <Foot>blah</Foot> </Obj2> </Root>

Here is my problem. I first convert my XML file to a DOM representation, in order to be able to do sequential processing. Indeed a mere XSLT transfo is of no help since I want to be able to do many thing between two actions. I then do the XPath evaluation but further modification of the resulting nodelist will never be reflected in the original XML files. I should say that I am using python 2.3, and Domlette/XPath from 4suite to do that.

My question is:

How can I use the resulting XPath result as a live representation of the underlying XML nodes (DOM concept) so that I can both perform sequential action (by traversing the resulting xpath nodelist) and reflects modifications done on those same nodes in the original XML file?

Maybe I am wrong on the live object concept of the DOM but I thought it would be possible. Any idea to achieve that would be welcome...

Phoebian

 

[Uche Ogbuji]

How can I use the resulting XPath result as a live representation of the underlying XML nodes (DOM concept) so that I can both perform sequential action (by traversing the resulting xpath nodelist) and reflects modifications done on those same nodes in the original XML file?

Maybe I am wrong on the live object concept of the DOM but I thought it would be possible. Any idea to achieve that would be welcome...

Actually, the results of 4XPath node set expressions are lists of actual Domlette nodes, and you can use the mutation API on these nodes. For the API see:

http://uche.ogbuji.net/tech/akara/nodes/2003-01-01/domlettes

You can then use Domlette.Print(node) to reflect the updates back to XML.

Did you try any particular mutations with no effect (or ill effect)?

FWIW, you might want to consider XUpdate, which is also implemented in 4Suite. I happen to cover it in my most recent ORA article:

http://www.xml.com/pub/a/2004/05/12/py-xml.html

--Uche
http://uche.ogbuji.net