Re: Accessing a Collection in p:variable

Hello Don,

The spec clearly says that when collection="true" the context item is 
undefined. You can access the collection through the collection() 
function, so something like collection()/c/@s might work (depending on 
whether there's only one /c/@s)

However, I haven't tested this, but I'm doubtful about your way of 
accessing files collection through the href attribute.

Maybe something like: <p:variable name="..." 
select="collection('files')/c/@s"/>  ??? (no collection="true")

And as a general remark: it is best practice to type your variables, so 
add an as="..." attribute with the intended outcome type.

Hope this helps, maybe not as a definite answer but as a tip.

Regards,
Erik Siegel


On 29/01/2026 13:00, Don Smith wrote:
> I'm using Morgana 1.4.5 on Windows.
>
> I want load a collection of XML files into a variable and then 
> retrieve information from one specific file but have been unable to 
> get it to work. I've a simplified example of the code I've got so far, 
> but here's a summary of the steps:
>
> 1. Establish source and result ports. Source file is input-main.xml
> 2. Create variable "new_s_value" to get collection of files in 
> subfolder "files"; use the unique root element of the target file to 
> identify the correct file in the collection and then get the desired 
> attribute value from the root element
> 3. Re-write the value of the target attribute "s" in the source file 
> using the new value from the collection (XSLT transform)
> 4. Output the new version of the input
>
> As you can see below (also in files in zip attachment), all this works 
> if I don't use a collection on the variable "new_s_value". But that's 
> only a test. I need to use a collection on variable "new_s_value" 
> because I won't ever be able to know the name of the target file. But 
> I'm missing something about how to access a collection on the 
> variable. The error I get from Morgana is
>
> "Error in XPath expression '/c/@s': Context item is needed, but not 
> provided: 1 items found"
>
> I've been unable to determine how to provide the missing XPath 
> context; I thought the @href would provide it but apparently not.
>
> XPROC:
> <p:declare-step xmlns:p="http://www.w3.org/ns/xproc" version="3.0" 
> name="main-step">
>     <p:input port="source" primary="true" href="input-main.xml" />
>     <p:output port="result" primary="true" sequence="true"/>
>     <!-- this works but is only a test -->
>     <!--<p:variable name="new_s_value" href="files/z3.xml" 
> select="/c/@s" />-->
>     <p:variable name="new_s_value" collection="true" 
> href="{collection(files)}" select="/c/@s" />
>     <p:xslt message="new s value: {$new_s_value}" 
> parameters="map{'new_s_value': $new_s_value}">
>        <p:with-input port="stylesheet" href="rewrite-s-value.xsl"/>
>    </p:xslt>
>     <p:store href="stored/rewrite-s-value.xml"></p:store>
> </p:declare-step>
>
> INPUT FILE input-main.xml
> <sample-source s="z5">
>     <div>
>         <section s="z5">
>             <title>Section level 1 title content.</title>
>             <div>
>                 <section s="z5">
>                     <title>Section level 2 title content.</title>
>                 </section>
>             </div>
>         </section>
>     </div>
> </sample-source>
>
> COLLECTION FILES IN SUBFOLDER "files"
> z1.zml
> <z s="no1">
>     <p>Z document with a paragraph.</p>
> </z>
>
> z2.xml
> <y s="no2">
>     <p>Y document with a paragraph.</p>
> </y>
>
> z3.xml
> <c s="t9">
>     <p>C document with a paragraph.</p>
> </c>
>
> XSLT rewrite-s-value.xsl
> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
>     xmlns:xs="http://www.w3.org/2001/XMLSchema"
> xmlns:math="http://www.w3.org/2005/xpath-functions/math"
>     exclude-result-prefixes="xs math"
>     version="3.0">
>     <xsl:param name="new_s_value" as="xs:string">default</xsl:param>
>     <xsl:template match="*">
>         <xsl:copy>
>             <xsl:if test="@s">
>                 <xsl:attribute name="s" select="$new_s_value"/>
>             </xsl:if>
>             <xsl:apply-templates/>
>         </xsl:copy>
>     </xsl:template>
> </xsl:stylesheet>
>
> Thanks,
>
> Don
>
>
>