CODEWITHSUNDEEP
xmlxslt
flyaround
flyaround

Reputation: 363

Nesting multiple XSLT templates with recursion

My XML is very flat, and here is an example:

<?xml version="1.0" encoding="UTF-8"?>
<Elements>
  <Header>
     <Divison>A</Divison>
     <ParentNumber>2016041330</ParentNumber>
  </Header>
  <Header>
     <Divison>C</Divison>
     <ParentNumber>2016041323</ParentNumber>
  </Header>
  <Element>
     <Number>2016041312</Number>
     <ParentNumber>2016041330</ParentNumber>
     <Risk>8</Risk>
  </Element>
  <Element>
     <Number>2016041342</Number>
     <ParentNumber>2016041323</ParentNumber>
     <Risk>2</Risk>
  </Element>
  <Element>
     <Number>2016041318</Number>
     <ParentNumber>2016041330</ParentNumber>
     <Risk>0</Risk>
  </Element>
  <Element>
     <Number>2016041330</Number>
     <ParentNumber>2016041323</ParentNumber>
     <Risk>7</Risk>
  </Element>
</Elements>

And they need to be nested in such a way that it displays as such:

<?xml version="1.0" encoding="UTF-8"?>
<Elements>
  <Header>
    <Divison>C</Divison>
    <ParentNumber>2016041323</ParentNumber>
    <Element>
       <Number>2016041342</Number>
       <ParentNumber>2016041323</ParentNumber>
       <Risk>2</Risk>
    </Element>
    <Header>
       <Divison>A</Divison>
       <ParentNumber>2016041330</ParentNumber>
       <Risk>7</Risk>
       <Element>
          <Number>2016041312</Number>
          <ParentNumber>2016041330</ParentNumber>
          <Risk>8</Risk>
       </Element>
       <Element>
          <Number>2016041318</Number>
          <ParentNumber>2016041330</ParentNumber>
          <Risk>0</Risk>
       </Element>
    </Header>
  </Header>
</Elements>

I tried it with the following transformation:

(Special thanks to michael.hor257k)

<xsl:stylesheet version="1.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:strip-space elements="*"/>

<xsl:key name="child-by-parent" match="Header | Element" use="ParentNumber" />
<xsl:key name="parent" match="Header | Element" use="Number" />

<!-- identity transform -->
<xsl:template match="@*|node()">
    <xsl:copy>
        <xsl:apply-templates select="@*|node()"/>
    </xsl:copy>
</xsl:template>

<xsl:template match="Elements">
    <xsl:copy>
        <xsl:apply-templates select="*[not(key('parent', ParentNumber))]"/>
    </xsl:copy>
</xsl:template>

<xsl:template match="Header | Element">
    <xsl:copy>
        <xsl:apply-templates select="@*|node()"/>
        <xsl:apply-templates select="key('child-by-parent', Number)"/>
    </xsl:copy>
</xsl:template>

</xsl:stylesheet>

with the following result:

<?xml version="1.0" encoding="UTF-8"?>
<Elements>
   <Header>
      <Divison>C</Divison>
      <ParentNumber>2016041323</ParentNumber>
   </Header>
   <Element>
      <Number>2016041342</Number>
      <ParentNumber>2016041323</ParentNumber>
      <Risk>2</Risk>
   </Element>
   <Element>
      <Number>2016041330</Number>
      <ParentNumber>2016041323</ParentNumber>
      <Risk>7</Risk>
      <Header>
         <Divison>A</Divison>
         <ParentNumber>2016041330</ParentNumber>
      </Header>
      <Element>
         <Number>2016041312</Number>
         <ParentNumber>2016041330</ParentNumber>
         <Risk>8</Risk>
      </Element>
      <Element>
         <Number>2016041318</Number>
         <ParentNumber>2016041330</ParentNumber>
         <Risk>0</Risk>
      </Element>
   </Element>
</Elements>

The [element] tag contains two kinds of information: number and parentnumber. The number is the distinct number of the [element]. The parentnumber references to another [element]. Are both the number and the parentnumber corresponding to a [header], then the [element] serves as a link and can be dissolved. However, if only the parentnumber is corresponding to the [header], than this assigns the [element] tag to a [header] tag.

Upvotes: 0

Views: 1622

Answers (1)

michael.hor257k
michael.hor257k

Reputation: 117073

I don't understand the logic by which you get your result. AFAICS, you have three elements with no parent node:

<Header>
  <Divison>C</Divison>
  <ParentNumber>2016041323</ParentNumber>
</Header>
<Element>
  <Number>2016041342</Number>
  <ParentNumber>2016041323</ParentNumber>
</Element>
<Element>
  <Number>2016041330</Number>
  <ParentNumber>2016041323</ParentNumber>
</Element>

so I would expect these to be siblings at the top level of the hierarchy. Then you would have each of these three branches nest their descendants recursively - to obtain:

<Elements>
   <Header>
      <Divison>C</Divison>
      <ParentNumber>2016041323</ParentNumber>
   </Header>
   <Element>
      <Number>2016041342</Number>
      <ParentNumber>2016041323</ParentNumber>
   </Element>
   <Element>
      <Number>2016041330</Number>
      <ParentNumber>2016041323</ParentNumber>
      <Header>
         <Divison>A</Divison>
         <ParentNumber>2016041330</ParentNumber>
      </Header>
      <Element>
         <Number>2016041312</Number>
         <ParentNumber>2016041330</ParentNumber>
      </Element>
      <Element>
         <Number>2016041318</Number>
         <ParentNumber>2016041330</ParentNumber>
      </Element>
   </Element>
</Elements>

This could be achieved by:

XSLT 1.0

<xsl:stylesheet version="1.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:strip-space elements="*"/>

<xsl:key name="child-by-parent" match="Header | Element" use="ParentNumber" />
<xsl:key name="parent" match="Header | Element" use="Number" />

<!-- identity transform -->
<xsl:template match="@*|node()">
    <xsl:copy>
        <xsl:apply-templates select="@*|node()"/>
    </xsl:copy>
</xsl:template>

<xsl:template match="Elements">
    <xsl:copy>
        <xsl:apply-templates select="*[not(key('parent', ParentNumber))]"/>
    </xsl:copy>
</xsl:template>

<xsl:template match="Header | Element">
    <xsl:copy>
        <xsl:apply-templates select="@*|node()"/>
        <xsl:apply-templates select="key('child-by-parent', Number)"/>
    </xsl:copy>
</xsl:template>

</xsl:stylesheet>

Upvotes: 1

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