RE: Key error: the context item is undefined

I imagine you want to search within the document that contains the $obj
node. In this case you can write

<xsl:value-of select="foo:do.it(key('by.id', $obj/@idref, $obj/root()))"/>

or if you prefer,

<xsl:value-of select="foo:do.it($obj/key('by.id', @idref))"/>

The reason for the error is that key(), with 2 arguments, always searches
the document containing the context node, and if there isn't a context node
then it doesn't know which document to search.

Michael Kay
http://www.saxonica.com/

> -----Original Message-----
> From: drkm [mailto:darkman_spam@xxxxxxxx]
> Sent: 12 December 2005 18:45
> To: XSL Mulberry list
> Subject:  Key error: the context item is undefined
>
>   Hi
>
>   I have a problem using a key.  I have an XPath function
> that can deal with elements that are identifiers for other
> elements.  In such a case, the function uses a key to
> retreive the effective element (corresponding to the id).
>
>   Saxon-SA 8.6.1 give me the following error message:
>
>     Error on line 13 of ~/drafts/key-wo-context.xsl:
>       XPDY0002: Cannot select a node here: the context item
>       is undefined
>
>   While I think I understand mostly what it means, I can't
> find a way to do what I want.  Below is a minimal example
> that reproduce the error:
>
>     ~/drafts $ cat key-wo-context.xsl
>     <xsl:transform
>         xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
>         xmlns:foo="..."
>         version="2.0">
>
>       <xsl:output method="text"/>
>
>       <xsl:key name="by.id" match="item" use="id"/>
>
>       <xsl:function name="foo:do.it">
>         <xsl:param name="obj"/>
>         <xsl:choose>
>           <xsl:when test="$obj/@idref">
>             <xsl:value-of
>                 select="foo:do.it(key('by.id', $obj/@idref))"/>
>           </xsl:when>
>           <xsl:otherwise>
>             <xsl:value-of select="."/>
>           </xsl:otherwise>
>         </xsl:choose>
>       </xsl:function>
>
>       <xsl:template match="/">
>         <xsl:value-of select="*[1]/*"/>
>       </xsl:template>
>
>     </xsl:transform>
>
>     ~/drafts $ cat key-wo-context.xml
>     <root>
>       <item id="a">A</item>
>       <item id="b">B</item>
>       <item idref="b"/>
>       <item id="c">C</item>
>       <item idref="c"/>
>       <item idref="a"/>
>       <item id="d">D</item>
>     </root>
>
>     ~/drafts $ saxon key-wo-context.xml key-wo-context.xsl
>     Error on line 13 of ~/drafts/key-wo-context.xsl:
>       XPDY0002: Cannot select a node here: the context item
>       is undefined
>     Failed to compile stylesheet. 1 error detected.
>
>   Do you have any idea?
>
>   Thanks,
>
> --drkm
>
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