Re: [xsl] Newbie question on XSL transformations: multiple sorts on element attributes

[Rob Newman <rlnewman@xxxxxxxx>]

Hi Abel,

You have got the point - your summary is correct.
Unfortunately that first sort (1) causes xsltproc to seg-fault again.  
I will keep trying to figure it out.

Thanks for all the help.
- Rob

On Feb 6, 2007, at 4:10 PM, Abel Braaksma wrote:

> Rob Newman wrote:
> > Datalogger elements right now are not sorted. Whichever comes  
> > first in input.xml gets output first in output.xml. I have no  
> > control of the order in input.xml. Hence the need to sort them.
>
> Thanks for the more verbose input. I often have the same trouble  
> getting my point through, but your last clarifications sure make  
> things easier. Let me summarize, to find out if I got the point now:
>
> 1. You want to order all datalogger elements based on the only  
> child element of pfarr, which is a pfstring and has an attribute  
> @name='dlt'. Highest number first.
> 2a. You do not want to order the param elements, because they are  
> already ordered
> 2b. You do want to order the param elements.
>
> I wasn't sure between 2a and 2b, so I give you both answers.  
> Resolving (1) first:
>
> <xsl:apply-templates select="pfarr/pfarr/pfarr" >
>   <xsl:sort select="pfstring[@name = 'dlt']"  data-type="number"  
> order="descending"/>
> </xsl:apply-templates>
>
> What this does is the following: for each pfarr element, it orders  
> for the child "pfstring" that has an attribute '@name' with the  
> value 'dlt'. You may be tempted to use the element names of the  
> output, but you should always use the nodes from the input (no  
> other possibility). The starting point for the expression always is  
> each element that is selected by the enclosing xsl:apply-templates.  
> Here, "pfarr/pfarr/pfarr" returns a selection of "pfarr" elements.  
> These are ordered based on there pfstring children. The trick I  
> always use to find out whether I have a legal path is, append them  
> together:
>
> "pfarr/pfarr/pfarr"  plus   "pfstring[@name = 'dlt']" yields:
> pfarr/pfarr/pfarr/pfstring[@name = 'dlt']
>
> if this resulting path is not correct, i.e. does not select  
> anything, the xsl:sort will not have any effect.
>
>
> Solving 2a: remove the other sorts.
>
> Solving 2b: leave only the following in place to order param  
> elements ascending and by name (in your example, both input and  
> output were sorted, so I wasn't sure you needed this)
>
>  <xsl:apply-templates select="pfstring">
>      <xsl:sort select="@name" />
>  </xsl:apply-templates>
>
>
> > Sorry about this - hopefully this cleans the canvas and it is  
> > clear to all what I am trying to do. Thanks again.
>
> np. See above.