[xquery-talk] Selecting everything before and after path, but without duplicated leafs

[J. Zhang]

Hi Michael,

Thanks, I will try to clear up things one by one below.

On Feb 10, 2008 11:30 PM, Michael Kay <mike at saxonica.com> wrote:
> Three points:
>
> (1) the preceding and following axes return each node once only. But if your
> document is
>
> <a>
>   <b>
>     <c/>
>   </b>
>   <d/>
> </a>
>
> then the preceding nodes of d are b and c, so if you do
>
> <before>{//d/preceding::*}</before>
>
> then the <before> element will contain a copy of b followed by a copy of c,
> which means that the result will be
>
> <before>
>   <b>
>     <c/>
>   </b>
>   <c/>
> </before>

OK, this was not totally clear to me yet. It makes sense that
"preceding" is first selecting the root, then all its descendants
recursive-like. This is causing what I called "duplicated" leafs. I
thought it would return elements from the root to the specified path,
and all the elements after the path, but is returning me also nested
elements, which is what I was not expecting.

> (2) You haven't really explained what output you want. If the input is
>
> <ead>
>   <banana/>
>   <archdesc>
>     <dsc>
>       <c00/>
>       <c01/>
>       <c02/>
>     </dsc>
>   </archdesc>
>   <custard/>
> </ead>
>
> what output would you like to see?

I would like to preserve the original XML file, but only add an extra
tag, so I would like to have this output:

<ead>
 <banana/>
 <archdesc>
   <dsc>
     <c00/>
     <SELECT>
     <c01/>
     </SELECT>
     <c02/>
   </dsc>
 </archdesc>
 <custard/>
</ead>

> (3) Transformations that involve copying most of the source document to the
> output unchanged while changing one or two nodes are generally easier to
> code in XSLT. Unless you have external constraints on your choice of tools
> (which isn't the case if you are using Saxon), then my advice is to use
> XQuery for queries, XSLT for transformations.

I am using XQuery because it seemed most easy for this task. I
actually have another XSLT for transforming XML files. I wanted to
generate a new XML file with XQuery from the old XML file, and apply a
stylesheet on that new XML file. I want to keep the whole XML file, so
preserve all the original structure, but just add one extra element.
The reason is that I want to use XPointer or XLink for jumping
directly in the XML file. I have my scripts ready, but proper XML file
reconstruction is something I cannot get working yet.

Thanks,

jz

> Michael Kay
> http://www.saxonica.com/
>
>
> > -----Original Message-----
> > From: talk-bounces at x-query.com
> > [mailto:talk-bounces at x-query.com] On Behalf Of Junte Zhang
> > Sent: 10 February 2008 11:34
> > To: talk at x-query.com
> > Subject: [xquery-talk] Selecting everything before and after
> > path,but without duplicated leafs
> >
> > Hi all,
> >
> > I have an XML file (quite long) and I have a path to an
> > element. I want to select
> > (1) everything of that path and its descendants, at the same
> > time I want to return everything (2) before that path, and
> > everything (3) after that path. I was trying the XPath axes
> > "preceding" and "following", but these axes are returning
> > duplicate leafs, which is not what I want. I would like to
> > reconstruct the original XML file, but with an extra tag for
> > the XPath selection ($unit).
> >
> > This is how my XQuery looks like.
> >
> >  let $doc := doc("file.xml")
> >
> >  let $precedingUnit :=
> > $doc/ead[1]/archdesc[1]/dsc[1]/c01[1]/preceding::node()
> >  let $unit := $doc/ead[1]/archdesc[1]/dsc[1]/c01[1]/self::node()
> >  let $followingUnit :=
> > $doc/ead[1]/archdesc[1]/dsc[1]/c01[1]/following::node()
> >  return
> >  <out>
> >   <before>
> >   {
> >      $precedingUnit
> >   }
> >   </before>
> >   <select>
> >   {
> >      $unit
> >   }
> >   </select>
> >   <after>
> >   {
> >      $followingUnit
> >   }
> >   </after>
> >   </out>
> >
> > I am using XQuery with Saxon: java -cp saxon9.jar
> > net.sf.saxon.Query query.xq
> >
> > Could you please help me?
> >
> > Thank you very much, I am really desperate in getting this working.
> >
> > Kind regards
> >
> > jz
> > _______________________________________________
> > talk at x-query.com
> > http://x-query.com/mailman/listinfo/talk
>
>