xsl:sort using an xsl:variable as the sort key

[jobooker]

I'm having issues sorting. The short description is, how do I set the
select attribute of xsl:sort to be the value of an xsl:variable? The
longer description follows:

What I want to do is to be able to make a data table sortable by
different headers. Right now, I've got javascript that lets you click
on a column header, and then it changes the DOM of the xsl file
(changes the select attribute of the xsl:sort element) and reapplies
the stylesheet to the xml file, and presents the newly resorted data.
However, the xpath for the select attribute gets ugly.

This is what it looks like now:
<xsl:sort select="item[key='main_contact']/value"/>

So my javascript is:
var sort_node=this.xslStylesheet.getElementsByTagName("sort").item(0);
sort_xpath="item[key='" + my_sort_param + "']/value";//ugly, JS has to
know a lot about xpath
sort_node.setAttribute("select",sort_xpath);

I'd rather my javascript be more like:
var
sort_param_node=this.xslStylesheet.getElementsByTagName("variable").item(0);
sort_node.setAttribute("select",my_sort_param); //prettier, JS just
knows a sort key, not the whole xpath

And so I think my xsl should be:
<xsl:variable name="sort_param" select="'main_contact'"/>
<xsl:sort select="item[key='$sort_param']/value"/>

But that doesn't work. I can't even get this to work:
<xsl:variable name="sort_param"
select="item[key='main_contact']/value"/>
<xsl:sort select="$sort_param"/>

I'm pretty confused at this point. I'm not sure where I'm going wrong.
It could be syntax, it might be misunderstanding how the variable works
with string literals vs element tree fragments, or...something else.
Any help is appreciated, thanks,
-John

 

[jobooker]

So apparently this does work afterall:
<xsl:variable name="sort_param" select="'name'"/>
<xsl:sort select="item[key=$sort_param]/value" />

Though I tried something like this first, and it blew up. Oh well,
problem solved for now,
-John

 

[Martin Honnen]

And so I think my xsl should be:
<xsl:variable name="sort_param" select="'main_contact'"/>
<xsl:sort select="item[key='$sort_param']/value"/>

You would need
<xsl:sort select="item[key=$sort_param]/value"/>
to have $sort_param interpreted as a variable. Your '$sort_param' is
simply a string literal which contains the text '$sort_param'.

And instead of using an xsl:variable and manipulating the stylesheet you
should use a top level
<xslaram name="sort_param" select="'main_contact'"/>
and then use the API your XSLT processor exposes to script to set that
parameter as needed.


Mozilla's API is described here:
<http://developer.mozilla.org/en/docs/Using_the_Mozilla_JavaScript_interface_to_XSL_Transformations>
Opera 9 uses the same API.