In XSLT how do I access elements from the outer loop from within nested loops?

Question

I have nested xsl:for loops:

<xsl:for-each select="/Root/A">
    <xsl:for-each select="/Root/B">
        <!-- Code -->
    </xsl:for>
</xsl:for>

From within the inner loop, how can I access attributes from the current node in the outer loop?

I keep finding myself writing code like this:

<xsl:for-each select="/Root/A">
    <xsl:variable name="someattribute" select="@SomeAttribute"/>
    <xsl:for-each select="/Root/B">
        <!-- Now can use $someattribute to access data from 'A' -->
    </xsl:for>
</xsl:for>

This doesn't scale very well, as sometimes I need to access several pieces of information and end up creating one variable for each piece. Is there an easier way?

Answer 1

You can store the entire /Root/A structure in a variable, and make reference to that variable rather than creating a new variable for every attribute and subelement you need to access.

<xsl:for-each select="/Root/A/">
    <xsl:variable name="ROOT_A" select="."/>
    <xsl:for-each select="/Root/B/">
         <!-- Variable is accessed like this: $ROOT_A/@someAttribute
              Just like a normal XML node -->
    </xsl:for-each>
</xsl:for-each>

Answer 2

Welbog has answered it well - but just to note you appear to be doing a cartesion (cross) join - is that intentional? If you are trying to do a regular join (with a predicate etc), then you want want to look into <xsl:key/> - i.e. declare a key:

<xsl:key name="BIndex" match="/Root/B" use="SomeChildNode"/>

then consume in your predicate:

<xsl:for-each select="/Root/A/">
    <xsl:variable name="ROOT_A" select="."/>
    <xsl:for-each select="key('BIndex', LocalNode)">
     <!-- -->
    </xsl:for-each>
</xsl:for-each>

This should be equivalent to (but much faster than) the predicate:

    <xsl:for-each select="/Root/B[SomeChildNode = current()/LocalNode]">

If you are grouping the data, then look at Muenchian grouping