Simple XSLT Problem (HELP PLEASE)

gaeawalker · October 10th, 2007, 01:42 AM

Hello everyone,

I'm fairly new to XML and XSLT, and am trying to use it's power as a web designer/developer. I have three files:

- markup.xml
- logic.xsl
- data.xml

I am trying to make the logic recognize every instance of the "resource" tag in the markup.xml. Once it does this it then uses the information to grab data from the data.xml file and output it to the viewer.

Here is the markup.xml:

Code:

<?xml version="1.0" encoding="utf-8"?>
<?xml-stylesheet type="text/xsl" href="logic.xsl"?>

<page>
    <resource idc="page.content"/>
</page>

And here is the data.xml:

Code:

<?xml version="1.0" encoding="utf-8"?>

<resources>
    <res id="page.content">It Works!</res>
</resources>

I don't need to tell you both of these files are simple and straight forward. Now let's take a look at the logic.xslt:

Code:

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

    <xsl:variable name="data" select="document('data.xml')/resources/res"/>

    <xsl:template match="page">
        <html>
            <head>
                <title>The Page</title>
            </head>
            <body>
                <xsl:apply-templates/>
            </body>
        </html>
    </xsl:template>

    <xsl:template match="resource">
        <xsl:param name="identity"><xsl:value-of select="@idc"/></xsl:param>
        <xsl:apply-templates select="concat($data,'[@id=&apos;',$identity,'&apos;]')"/>
    </xsl:template>

</xsl:stylesheet>

The logic.xsl first defines a variable needed to know where to look for the data every time the $data variable is used. Next it outputs the standard XHTML markup with a template. Near the bottom it matches all <resource> tags. This is where the magic is suppose to happen. In theory it would grab all the data, depending on the value of the <resource> attribute, from the selected element of the data.xml.

Again I am new to this so perhaps it's an obvious mistake I do not see. I am suspecting perhaps you can have document(concat()) but not concat(document()). If this is so please let me know.

Thank you so much for any and all help you can provide.

mhkay · October 10th, 2007, 02:14 AM

The expression used in apply-templates select="" must return a set of nodes; but the concat() function returns a string. The string that it returns is

It works![@id='',$identity,'']

which doesn't seem very useful.

You seem to be trying to construct an XPath expression on the fly, which is not something XSLT allows. (There are extensions to do it, e.g. saxon:evaluate(), but it's not clear that you need them here).

I think you're making it far too complicated: you just want

select="$data[@id=$identity]"

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

gaeawalker · October 10th, 2007, 10:27 AM

Thank you! Thank you thank you thank you! It does indeed work. I've been trying to wrestle with this one around in my head for a while. My problem was just as you guessed it: I was making things entirely too complicated.

I owe you one. :)