Hi,

I am trying to assign a variable to a value which I can use in a for-each loop. Eg.

<xsl:variable name="source" select = "NewDataSet/Relation/Source"/>
(Where NewDataSet/Relation/Source has a value of "..//Table7").

When I try to use this in my for-each it doesn't work. However, if I assign the variable to the value
<xsl:variable name="source" select = "..//Table7"/> it works.

Grateful for any help/advice

<xsl:variable name="source" select = "NewDataSet/Relation/Source"/>
(Where NewDataSet/Relation/Source has a value of "..//Table7").

So the value of $source is the string "..//Table7"

When I try to use this in my for-each it doesn't work.

You mean you're doing

<xsl:for-each select="$source">

Well, in XSLT 1.0, the value of the select attribute has to be a node-set and as we saw earlier the value of $source is a string. Did you imagine that the system would magically recognize that the string "../Table7" looks like a path expression and should therefore be automatically compiled and evaluated to produce a node-set?

Standard XSLT (whether 1.0 or 2.0) doesn't have any built-in capability to evaluate path expressions that are constructed at run-time from strings, or read from source documents. Many products have extensions that do this (see for example saxon:evaluate) though the details of how they handle context, namespaces, etc, varies from one product to another.

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

Michael,

Thanks for the quick response. To be honest I wasnt sure if it would work at all, but trying to use my limited XSLT knowledge to come up with a solution.

So presumably assigning the equally string like value "..//Table7" directly to the variable works the as this is picked up as a node set ?

Is there a better way of trying to achieve this ?


Alex

Michael,

Thanks for the quick response. To be honest I wasnt sure if it would work at all, but trying to use my limited XSLT knowledge to come up with a solution.

So presumably assigning the equally string like value "..//Table7" directly to the variable works the as this is picked up as a node set ?

Is there a better way of trying to achieve this ?


Alex

Michael,

Thanks for the quick response. To be honest I wasnt sure if it would work at all, but trying to use my limited XSLT knowledge to come up with a solution.

So presumably assigning the equally string like value "..//Table7" directly to the variable works as this is recognised as a node set ?

Is there a better way of trying to achieve this ?

Michael,

Thanks for the quick response. To be honest I wasnt sure if it would work at all, but trying to use my limited XSLT knowledge to come up with a solution.

So presumably assigning the equally string like value "..//Table7" directly to the variable works the as this is picked up as a node set ?

Is there a better way of trying to achieve this ?

When you do

select="../Table7"

the value of the select attribute is an XPath expression, which is evaluated to return a set of nodes

When you do

select="$path"

the value of the select attribute is an XPath expression, which is evaluated to return a string, perhaps the string "../Table7". So what you're looking for is not "evaluate this expression", but "evaluate this expression to produce another expression and then evaluate that expression". This is precisely what saxon:evaluate() does.

If you have XPath expressions in source documents, there are two ways of handling them. You can use extensions such as saxon:evaluate() (or your own extension function written in Javascript if you're in the MSXML/DOM world). Or you can write a stylesheet that generates a stylesheet, and then run that stylesheet. Both are perfectly respectable things to do, but both require more than pure XSLT coding.

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

Michael,

Thanks for your help. Cheers.