Question

I have an xsl:param that I’m trying to use to do a template match on an attribute. By everything I’ve found here and on the Internet, I’m doing this correctly. However, my output is blank.

Here is my xslt

<xsl:param name="strm_name">main</xsl:param>    
<xsl:template match="stream[@name='{$strm_name}']"></xsl:template>

If I hardcode the param call to “main”, this works just fine.
Here is the XML tag I’m trying to match to..

<doc><stream name="main"></stream></doc>

Any help is much appreciated!

Answer 1

I see two issues:

1. You cannot use a variable or parameter reference in a match pattern in XSLT 1.0
2. You do not need the surrounding '{...}' when referencing your parameter in the predicate. (You’re probably confusing this with an Attribute Value Template.) Use this instead: stream[@name=$strm_name]

A possible workaround for issue #1 is to select only those elements that meet the criteria controlled by your param. (You can reference a param in a select expression).

For example, this stylesheet:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="text" />
    <xsl:param name="strm_name" select="'main'"/>
    <xsl:template match="/">
        <xsl:apply-templates select="/*/stream[@name=$strm_name]" />
    </xsl:template>
    <xsl:template match="stream">
        <xsl:apply-templates />
        <xsl:text>/</xsl:text>
    </xsl:template>
</xsl:stylesheet>

Applied to this document:

<root>
    <stream name="main">1</stream>
    <stream name="other">2</stream>
    <stream name="main">3</stream>
    <stream name="main">4</stream>
    <stream name="other">5</stream>
    <stream name="other">6</stream>
</root>

…matches only the desired nodes. Output:

1/3/4/