Question

I’m trying to recursively flatten / normalize a structure below with no luck.

<models>
  <model name="AAA" root="true">
    <items>
        <item name="a"/>
        <item name="b"/>
    </items>
    <submodels>
        <submodel ref="BBB"/>
        <submodel ref="CCC" />
    </submodels>
  </model>
  <model name="BBB">
    <items>
        <item name="c"/>
        <item name="d"/>
    </items>
    <submodels>
        <submodel ref="CCC" />
    </submodels>
  </model>
  <model name="CCC">
    <item name="e" />
  </model>
</models>

The expected result is the following:

/AAA
/AAA/a
/AAA/b
/AAA/BBB
/AAA/BBB/c
/AAA/BBB/d
/AAA/BBB/CCC
/AAA/BBB/CCC/e
/AAA/CCC
/AAA/CCC/e

I have tried using in a recursive way. But the main issue is that several models can refer to a single model. Eg. AAA -> CCC and BBB -> CCC.

Answer 1

This short and simple transformation:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="text"/>

  <xsl:key name="kmodelByName" match="model" use="@name"/>
  <xsl:key name="ksubmodelByRef" match="submodel" use="@ref"/>

  <xsl:template match="/*">
   <xsl:apply-templates select="model[not(key('ksubmodelByRef', @name))]"/>
  </xsl:template>

    <xsl:template match="model|item">
      <xsl:param name="pPath"/>
      <xsl:value-of select="concat('&#xA;', $pPath, '/', @name)"/>
      <xsl:apply-templates select="item|*/item|*/submodel">
       <xsl:with-param name="pPath" select="concat($pPath, '/', @name)"/>
      </xsl:apply-templates>
    </xsl:template>

    <xsl:template match="submodel">
      <xsl:param name="pPath"/>
      <xsl:apply-templates select="key('kmodelByName', @ref)">
        <xsl:with-param name="pPath" select="$pPath"/>
      </xsl:apply-templates>
    </xsl:template>
</xsl:stylesheet>

when applied on the provided XML document:

<models>
    <model name="AAA" root="true">
        <items>
            <item name="a"/>
            <item name="b"/>
        </items>
        <submodels>
            <submodel ref="BBB"/>
            <submodel ref="CCC" />
        </submodels>
    </model>
    <model name="BBB">
        <items>
            <item name="c"/>
            <item name="d"/>
        </items>
        <submodels>
            <submodel ref="CCC" />
        </submodels>
    </model>
    <model name="CCC">
        <item name="e"/>
    </model>
</models>

produces the wanted, correct result:

/AAA
/AAA/a
/AAA/b
/AAA/BBB
/AAA/BBB/c
/AAA/BBB/d
/AAA/BBB/CCC
/AAA/BBB/CCC/e
/AAA/CCC
/AAA/CCC/e

Explanation:

1. Proper use of keys makes the transformation short, easy to express and efficient.

2. Proper use of templates.

3. Proper use of parameter – passing to templates.