how to display content that appears once outside the repeating nodes in the expression of every node in xslt - variables

Question

I've got data in XML that has some header information then a series of items. I'm using XSLT to translate that into a different format, also with a header area and a series of items.
However in the post translation result, I want one piece of data only found in the header to be included in every instance of the items, even though it will simply be repeating the same value. (this value may change so I cannot hard code it)
Sample data (significantly simplified)
<rss>
<channel>
<title>Playlist One</title>
<items>
<item>
<title>Video One</title>
</item>
<item>
<title>Video Two</title>
</item>
<item>
<title>Video Three</title>
</item>
</items>
</channel>
</rss>
My desired result is something like this:
playlist_header_title=Playlist One
playlist_title=Playlist One
video_title=Video One
playlist_title=Playlist One
video_title=Video Two
playlist_title=Playlist One
video_title=Video Three
My XSLT is very complicated (and unfortunately I inherited it from someone else so I'm not sure what everything does, I've self-taught myself online but am in a bit over my head)
Roughly the key pieces look like this:
<xsl:template name="rss" match="/">
<xsl:variable name="playlist_title">
<xsl:value-of select="string(/rss/channel/title)"/>
</xsl:variable>
<xsl:for-each select="rss">
<xsl:apply-templates name="item" select="channel/items/item"/>
</xsl:for-each>
</xsl:template>
Then there's a massive template called "item" that I won't include here, but basically it outputs all the item data as desired, I just can't figure out how to access the "playlist_title".
When I try to call (from inside the template "item")
<xsl:value-of select="string($playlist_title)"/>
it returns a blank. I assume this is because that variable was created outside the for-each loop and so it not available. (it will display the data correctly when I output it before the for-each loop in the result's version of the header, but that doesn't get me far enough)
I've tried using with-param in the apply-templates, and also tried changing it to call-template inside another loop also using with-param, but they also display a blank.
I've also tried sending in a string rather than pulling the playlist_title from the XML just to confirm I am able to pass any value into the template, but they too come out blank.
For instance:
<xsl:for-each select="channel/items/item">
<xsl:call-template name="item">
<xsl:with-param name="playlist_title">blah</xsl:with-param>
</xsl:call-template>
</xsl:for-each>
<xsl:template name="item">
<xsl:param name="playlist_title" />
playlist_title=<xsl:value-of select="string($playlist_title)"/>
video_title=...
...
</xsl:template>
This did not return the value "blah" but just a blank. (my hope was to then replace "blah" with the playlist_title value pulled from the XML, but none of it is getting through)
I'm stumped! Thanks for any help.

Answer 1

In your first example, attempting to reference the $playlist_title inside of your template for item is failing because the variable does not exist inside of that template. It was created inside of the template match for rss and is locally scoped.
If you want to be able to use the $playlist_title in other templates, you need to declare it outside of the rss template in the "global scope".
For instance:
<xsl:variable name="playlist_title">
<xsl:value-of select="string(/rss/channel/title)"/>
</xsl:variable>
<xsl:template name="rss" match="/">
<xsl:for-each select="rss">
<xsl:apply-templates name="item" select="channel/items/item"/>
</xsl:for-each>
</xsl:template>
As for your second attempt, referencing the xsl:param playlist_title, it worked for me. Double-check to ensure that you don't have a type-o or other difference between the name of the parameter that was declared and the name of the parameter that you are referencing.
You might try something like this to achieve your desired output, using an xsl:variable:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text" indent="yes"/>
<xsl:variable name="playlist_title" select="/rss/channel/title" />
<xsl:template match="/">
<xsl:apply-templates select="rss/channel"/>
</xsl:template>
<xsl:template match="channel">
<xsl:text>playlist_header_title=</xsl:text>
<xsl:value-of select="title"/>
<xsl:text>
</xsl:text>
<xsl:apply-templates select="items/item"/>
</xsl:template>
<xsl:template match="item">
<xsl:text>playlist_title=</xsl:text>
<xsl:value-of select="$playlist_title"/>
<xsl:text>
</xsl:text>
<xsl:text>video_title=</xsl:text>
<xsl:value-of select="title"/>
<xsl:text>
</xsl:text>
</xsl:template>
</xsl:stylesheet>
Or you can eliminate the xsl:variable and use an xsl:param:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text" indent="yes"/>
<xsl:template match="/">
<xsl:apply-templates select="rss/channel"/>
</xsl:template>
<xsl:template match="channel">
<xsl:text>playlist_header_title=</xsl:text>
<xsl:value-of select="title"/>
<xsl:text>
</xsl:text>
<xsl:apply-templates select="items/item">
<xsl:with-param name="playlist_title" select="title"/>
</xsl:apply-templates>
</xsl:template>
<xsl:template match="item">
<xsl:param name="playlist_title" />
<xsl:text>playlist_title=</xsl:text>
<xsl:value-of select="$playlist_title"/>
<xsl:text>
</xsl:text>
<xsl:text>video_title=</xsl:text>
<xsl:value-of select="title"/>
<xsl:text>
</xsl:text>
</xsl:template>
</xsl:stylesheet>