RE: [xsl] XSL/XPath Dynamic sort key

["Michael Kay" <mhk@xxxxxxxxx>]

> I know I know, it's not possible.

You're right. Well, almost.

The select="*[name()=$param]" trick only works for single level "child
element" selections. You can try stretching it to other cases, but it's
going to get combinatorially difficult.

I would go with one of the other possible approaches, which are:

(a) generate the XPath expression dynamically, using xx:evaluate() if
your processor offers this extension

(b) generate (or modify) the stylesheet dynamically before you run it.

Michael Kay



  Well I've got this line 
> working so far, 
> so I'm halfway through the "this is impossible in XSL" 
> process so far.  
> First some params, then some XSL.
> 
> <xsl:param name="sort_select_lvl_1">author</xsl:param>
> <xsl:param name="sort_select_lvl_2">/</xsl:param>
> <xsl:param name="sort_select_lvl_3">last_name</xsl:param>
> <xsl:param name="sort_order">ascending</xsl:param>
> <xsl:param name="sort_data_type">text</xsl:param>
> 
> <xsl:apply-templates select="document">
>   <xsl:sort select="*[name()=$sort_select_lvl_1]" 
> data-type="{$sort_data_type}" order="{$sort_order}" /> 
> </xsl:apply-templates>
> 
> 
> Now here's what I want.  Sometimes I want to sort by uid, 
> accesses, which 
> works fine.  Other times I want to sort by author/last_name.  
> Now I can do 
> this by changing the sort line to this...
> 
> <xsl:sort 
> select="*[name()=$sort_select_lvl_1]\*[name()=$sort_select_lvl_2]" 
> data-type="{$sort_data_type}" order="{$sort_order}" />
> 
> But then it doesn't work for uid or accesses anymore because 
> the "\" at the 
> end of the string.  If I remove the "\" i get a number 
> expected error.  So 
> I've come up with half a way around it.  I figure I will have lots of 
> variables at the top, lvl_1 through 4 so that I can fill them 
> all with parts 
> of an xpath statement and then join them togather.  So I try it and 
> unfortunately xpath's concat does not let the sort select 
> evaluate the xpath 
> statement.  In other words
> 
> xsl:sort select="concat('author','/','last_name')" />
> is not the same as
> <xsl:sort select="author/last_name" />
> 
> So how do I string togather the *[name()=$sort_select_lvl_1], 
> one directly 
> after the other?  I set the defaults in the xslt above to reflect a 
> reference to "author/last_name".
> 
> 
> Glimpse of XML
> 
> <catalog>
>   <document>
>     <uid>2301</uid>
>     <url>http://www.who.com/document.htm</url>
>     <subject>General Stuff</subject>
>     <abstract>This is an abstractabstract>
>     <accesses>1</accesses>
>     <age>4</age>
>     <last_accessed date="20011229">12/29/2001</last_accessed>
>     <author>
>       <first_name>Peon</first_name>
>       <last_name>lover</last_name>
>       <serial>9A1551645</serial>
>     </author>
>     <owner>
>       <first_name>Jolly</first_name>
>       <last_name>Goose</last_name>
>       <serial>123456</serial>
>     </owner>
>     <manager>
>       <first_name>Someone</first_name>
>       <last_name>Special</last_name>
>       <serial>123456</serial>
>     </manager>
>     <supervisor>
>       <first_name>Someone</first_name>
>       <last_name>Important</last_name>
>       <serial>123456</serial>
>     </supervisor>
>   </document>
>   ...
> </catalog>
> 
> Thanks in advance!
> 
> Aaron
> 
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