conditional loop in XSLT

Question

I have a sample XML which have to loop 3 times to get output. But sometime, one of the loop (attrQualMany name="pagecontain") can be optional, which is creating problem here.

The sample XML is

<document>
<item>
<ID>1000909090</ID>
<flex>
    <attrGroupMany name="pageinfo">
        <row>
            <attrQualMany name="pageinput">
                <value qual="en">User Intake</value>
            </attrQualMany>
            <attrGroupMany name="pagetype">   <!-- Mandatory Loop -->
                <row>
                    <attr name="pagemeasure">EXACT</attr> 
                    <attrQualMany name="pagecontain">  <!-- Optional Loop -->
                        <value qual="GR1">20</value>
                        <value qual="GR2">21</value>
                    </attrQualMany>
                </row>
                <row>
                    <attr name="pagemeasure">EXACT1</attr> 
                    <attrQualMany name="pagecontain"><!-- Optional Loop -->
                        <value qual="JH1">30</value>
                        <value qual="JH2">31</value>
                    </attrQualMany>
                </row>
            </attrGroupMany>
            <attr name="pagestate">PREPARED</attr>
            <attrQualMany name="pagewidth">  <!-- Mandatory Loop -->
                <value qual="OZ">10</value>
                <value qual="AB">11</value>
            </attrQualMany>
        </row>
    </attrGroupMany>
</flex>
</item>
</document>

I am using below XSLT which is working fine when we have all the loops present.

XSLT

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:output method="xml" indent="yes" />
<xsl:template match="/document">
    <CatalogItem>
        <RelationshipData>
            <Relationship>
                <RelationType>PAGEDETAILSINFO</RelationType>
                <xsl:variable name="pagetype" select="//attrGroupMany[@name = 'pagetype']/row"/>
                <xsl:variable name="pagecontain" select="$pagetype//attrQualMany[@name='pagecontain']"/>
                <xsl:variable name="pagewidth" select="//attrQualMany[@name = 'pagewidth']/value"/>
                <RelatedItems count="{count($pagetype) * count($pagecontain) * count($pagewidth)}">
                    <xsl:for-each select="$pagetype">
                        <xsl:variable name="attr" select="attr[@name='pagemeasure']"/>
                        <xsl:for-each select=".//attrQualMany[@name='pagecontain']/value">
                            <xsl:variable name="value" select="."/>
                            <xsl:variable name="value1" select="./@qual"/>
                            <xsl:for-each select="$pagewidth">
                                <RelatedItem referenceKey="{concat('PAGEDETAILSINFO','-',ancestor::item/ID,'-',../../attr[@name='pagestate'], '-', . ,'-', @qual, '-', $attr , '-',$value, '-', $value1)}"/>
                            </xsl:for-each>
                        </xsl:for-each>
                    </xsl:for-each>
                </RelatedItems>
            </Relationship>
        </RelationshipData>
    </CatalogItem>
</xsl:template>
</xsl:stylesheet>

If the XML is not having optional loop and looks like below, it is not returning any value

<document>
<item>
    <ID>1000909090</ID>
    <flex>
        <attrGroupMany name="pageinfo">
            <row>
                <attrQualMany name="pageinput">
                    <value qual="en">User Intake</value>
                </attrQualMany>
                <attrGroupMany name="pagetype">
                    <row>
                        <attr name="pagemeasure">EXACT</attr>
                    </row>
                    <row>
                        <attr name="pagemeasure">EXACT1</attr>
                    </row>
                </attrGroupMany>
                <attr name="pagestate">PREPARED</attr>
                <attrQualMany name="pagewidth">
                    <value qual="OZ">10</value>
                    <value qual="AB">11</value>
                </attrQualMany>
            </row>
        </attrGroupMany>
    </flex>
</item>
</document>

Expected output in this case is

<?xml version="1.0" encoding="UTF-8"?>
<CatalogItem>
<RelationshipData>
    <Relationship>
        <RelationType>PAGEDETAILSINFO</RelationType>
        <RelatedItems count="8">
            <RelatedItem referenceKey="PAGEDETAILSINFO-1000909090-PREPARED-10-OZ-EXACT--"/>
            <RelatedItem referenceKey="PAGEDETAILSINFO-1000909090-PREPARED-11-AB-EXACT--"/>
            <RelatedItem referenceKey="PAGEDETAILSINFO-1000909090-PREPARED-10-OZ-EXACT1--"/>
            <RelatedItem referenceKey="PAGEDETAILSINFO-1000909090-PREPARED-11-AB-EXACT1--"/>
        </RelatedItems>
    </Relationship>
</RelationshipData>
</CatalogItem>

Answer 1

Consider making the for-loop that matches your current $pagewidth variable a template instead.

<xsl:template match="attrQualMany[@name = 'pagewidth']/value">
    <xsl:param name="pagetype" />
    <xsl:param name="pagecontain" />
    <xsl:param name="pagecontainqual" />
    <RelatedItem referenceKey="{concat('PAGEDETAILSINFO','-',ancestor::item/ID,'-',../../attr[@name='pagestate'], '-', . ,'-', @qual, '-', $pagetype , '-', $pagecontain, '-', $pagecontainqual)}"/>
</xsl:template>

You can then have an xsl:choose to determine if there are any pagecontain values

<xsl:variable name="pagecontain" select=".//attrQualMany[@name='pagecontain']/value"/>
   <xsl:choose>
      <xsl:when test="$pagecontain">

If the condition is true, then you can call the new template instead of having a nested xsl:for-each

<xsl:for-each select="$pagecontain">
  <xsl:apply-templates select="$pagewidth">
     <xsl:with-param name="pagetype" select="$attr" />
     <xsl:with-param name="pagecontain" select="." />
     <xsl:with-param name="pagecontainqual" select="@qual" />
  </xsl:apply-templates>

Otherwise, you just call the template without the xsl:for-each

<xsl:apply-templates select="$pagewidth">
   <xsl:with-param name="pagetype" select="$attr" />
</xsl:apply-templates>

Try this XSLT

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:output method="xml" indent="yes" />
<xsl:template match="/document">
    <CatalogItem>
        <RelationshipData>
            <Relationship>
                <RelationType>PAGEDETAILSINFO</RelationType>
                <xsl:variable name="pagetype" select="//attrGroupMany[@name = 'pagetype']/row"/>
                <xsl:variable name="pagecontain" select="$pagetype//attrQualMany[@name='pagecontain']"/>
                <xsl:variable name="pagewidth" select="//attrQualMany[@name = 'pagewidth']/value"/>
                <RelatedItems count="{count($pagetype) * count($pagecontain) * count($pagewidth)}">
                    <xsl:for-each select="$pagetype">
                        <xsl:variable name="attr" select="attr[@name='pagemeasure']"/>
                        <xsl:variable name="pagecontain" select=".//attrQualMany[@name='pagecontain']/value"/>
                        <xsl:choose>
                            <xsl:when test="$pagecontain">
                                <xsl:for-each select="$pagecontain">
                                    <xsl:apply-templates select="$pagewidth">
                                        <xsl:with-param name="pagetype" select="$attr" />
                                        <xsl:with-param name="pagecontain" select="." />
                                        <xsl:with-param name="pagecontainqual" select="@qual" />
                                    </xsl:apply-templates>
                                </xsl:for-each>
                            </xsl:when>
                            <xsl:otherwise>
                                <xsl:apply-templates select="$pagewidth">
                                    <xsl:with-param name="pagetype" select="$attr" />
                                </xsl:apply-templates>
                            </xsl:otherwise>
                        </xsl:choose>
                    </xsl:for-each>
                </RelatedItems>
            </Relationship>
        </RelationshipData>
    </CatalogItem>
</xsl:template>

<xsl:template match="attrQualMany[@name = 'pagewidth']/value">
    <xsl:param name="pagetype" />
    <xsl:param name="pagecontain" />
    <xsl:param name="pagecontainqual" />
    <RelatedItem referenceKey="{concat('PAGEDETAILSINFO','-',ancestor::item/ID,'-',../../attr[@name='pagestate'], '-', . ,'-', @qual, '-', $pagetype , '-', $pagecontain, '-', $pagecontainqual)}"/>
</xsl:template>
</xsl:stylesheet>