Using XSLT arguments for in XML paths

jacob · November 5th, 2005, 06:37 PM

Currently I am trying to use the XsltArgumentList in XML transformation done from code-behind in an ASP.NET application. However, I have some problems using the arguments in XML paths. In the following code I would like to replace someone with the user argument, as used later in an attribute...

Code:

    <xsl:template match="users">
        <xsl:apply-templates select="user[@name='someone']" />        
    </xsl:template>
    <xsl:template match="user[@name='someone']">
        <input type="text" value="{$user}" />
    </xsl:template>

I have tried using the same notation but without succes. Is it possible and so, how?

Thanks, Jacob.

mhkay · November 5th, 2005, 06:49 PM

XSLT 1.0 doesn't allow a variable to be used in a match pattern. This restriction is removed in XSLT 2.0. (It has also been removed in some products which in other respects conform to the XSLT 1.0 spec.)

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

jacob · November 5th, 2005, 06:55 PM

Alright, thanks for the speedy reply.

I guess I have to try it is possible in some other way, e.g. using if statement or like. I am trying to make a style sheet, which will display only one profile from a number of users in the XML file. Though the correct way would be to select and not eliminate.

Thanks, Jacob.

jacob · November 5th, 2005, 07:01 PM

Damn, it doesn't seem to work either. I guess I am out of luck. Isn't there another way to make processing logic based on an argument? Tried this

Code:

<xsl:if test="@name='{$user}'">

... but not working the way I want.

Jacob.

mhkay · November 5th, 2005, 08:19 PM

You only want curly braces around the outside of an XPath expression that's embedded in an attribute whose value would otherwise be literal text (these are called attribute value templates). In the middle of an XPath expression, just write:

<xsl:if test="@name=$user">

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

jacob · November 7th, 2005, 06:16 AM

Coooool Michael Kay... That was great.

Thought I had tried that combination (without quotes and curly braces). Thanks for the clarification on the use of curly braces; so the right-hand side expression in an if is an XPath and the variable is allowed, and in the match expression it is not. I guess the match expression is also an XPath so it must clearly be a deliberate restriction not to allow variables, right?

Thanks again, Jacob.

mhkay · November 7th, 2005, 10:03 AM

XSLT match patterns are actually a subset of XPath expressions (2+2 is a valid XPath expression but not a valid pattern). Yes, it was a deliberate decision to disallow variables. The reason (misguided with hindsight) was to prevent circular definitions such as

<xsl:variable name="x">
<xsl:apply-templates select="//a"/>
</xsl:variable>

<xsl:template match="a[$x = 3]">
Looping!
</xsl:template>

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

jacob · November 7th, 2005, 11:04 AM

Ahhh, I see. Thanks for your help, Jacob.