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xml xslt xslt-1.0

Get a common id to all ancestors from the lowest member

发布于 2020-03-30 21:14:33

Trying to assembly correct XSLT-code to assign common id which is taken from the lowest member (from its "uniq-id") of the recursive chain to all elements above. Can't get ancestors' nodes.

source xml

<root>
  <Object id="top"                        uniq-id="001" status="0" rank="1"/>
  <Object id="middle"  id-parent="top"    uniq-id="020" status="0" rank="3"/>
  <Object id="middle"  id-parent="top"    uniq-id="021" status="1" rank="3"/>

  <!--   only the element with status="0" is considered -->

  <Object id="bottom-1"  id-parent="middle" uniq-id="111" status="1" rank="6" />
  <Object id="bottom-2"  id-parent="middle" uniq-id="222" status="1" rank="6" />
  <Object id="bottom-3"  id-parent="middle" uniq-id="333" status="0" rank="6" />  <!-- will be taken -->
  <Object id="bottom-4"  id-parent="middle" uniq-id="444" status="1" rank="6" />
  <Object id="bottom-5"  id-parent="middle" uniq-id="555" status="1" rank="7" />
  <Object id="bottom-6"  id-parent="middle" uniq-id="666" status="0" rank="7" />  <!-- will be taken -->
  <Object id="bottom-7"  id-parent="middle" uniq-id="777" status="1" rank="6" />
  <Object id="bottom-8"  id-parent="middle" uniq-id="888" status="1" rank="6" />
  <Object id="bottom-9"  id-parent="middle" uniq-id="999" status="0" rank="6" />  <!-- will be taken -->
</root>

starting-xslt

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
   xmlns:exslt="http://exslt.org/common">
  <xsl:key name="Object-By-id"        match="Object[(@status='0')]"  use="@id"/>
  <xsl:key name="Object-By-id-parent" match="Object[(@status='0')]"  use="string(@id-parent)"/>

  <xsl:variable name="fold-rtf">
    <xsl:apply-templates select="/" mode="fold"/>
  </xsl:variable>
  <xsl:variable name="folded-tree" select="exslt:node-set($fold-rtf)"/>

  <xsl:template match="@*|node()[(@status='0')]">
    <xsl:copy>
      <xsl:apply-templates select="@* | node()[(@status='0')]"/>
    </xsl:copy>
  </xsl:template>

  <xsl:template match="Object[@status=0]/@*[last()]">
    <xsl:variable name="current" select=".."/>
    <xsl:copy/>
    <xsl:for-each select="$folded-tree">
      <xsl:for-each select="key('Object-By-id',$current/@id)">

        <!-- ====== !!  =======-->

        <xsl:if test="position()!=last()">
          <xsl:for-each select="ancestor-or-self::*">
            <xsl:attribute name="chain-id">
              <xsl:value-of select="@uniq-id"/>
            </xsl:attribute>
          </xsl:for-each>
        </xsl:if>

        <!-- ======= !! =======-->

      </xsl:for-each>
    </xsl:for-each>
  </xsl:template>

  <xsl:template match="/|*" mode="fold">
    <xsl:copy>
      <xsl:copy-of select="@*"/>
      <xsl:apply-templates select="key('Object-By-id-parent',string(@id))" mode="fold">
      </xsl:apply-templates>
    </xsl:copy>
  </xsl:template>
</xsl:stylesheet>

the result (not correct) https://xsltfiddle.liberty-development.net/94Acsm2/1

assumed output

<root>
  <Object id="top"                          uniq-id="001" status="0" rank="1" chain-id="20"/>
  <Object id="middle"    id-parent="top"    uniq-id="020" status="0" rank="3" chain-id="20"/>

  <Object id="bottom-3"  id-parent="middle" uniq-id="333" status="0" rank="6" chain-id="333"/>
  <Object id="middle"    id-parent="top"    uniq-id="020" status="0" rank="3" chain-id="333"/>
  <Object id="top"                          uniq-id="001" status="0" rank="1" chain-id="333"/>

  <Object id="bottom-6"  id-parent="middle" uniq-id="666" status="0" rank="7" chain-id="666"/>
  <Object id="middle"    id-parent="top"    uniq-id="020" status="0" rank="3" chain-id="666"/>
  <Object id="top"                          uniq-id="001" status="0" rank="1" chain-id="666"/>

  <Object id="bottom-9"  id-parent="middle" uniq-id="999" status="0" rank="6" chain-id="999"/>
  <Object id="middle"    id-parent="top"    uniq-id="020" status="0" rank="3" chain-id="999"/>
  <Object id="top"                          uniq-id="001" status="0" rank="1" chain-id="999"/>
</root>

Welcome all your solutions how to improve XSLT-code

Questioner
Alex
Viewed
69
Michael Kay 2020-01-31 22:36

It's always difficult to reverse engineer your requirements from non-working code, but I think what you're trying to do is to select elements with @status="0", and for each of these, display the logical ancestors, that is, the recursive expansion of the relation parent(X), where parent(X) selects the element whose @id is equal to X/@parent-id.

It's a long time since I coded in XSLT 1.0 (it's been superseded for a long time now...) so apologies if I make any errors.

First define a key that selects objects by id:

<xsl:key name="by-id" match="Object" use="@id"/>

Now define a recursive template to print the logical ancestors of a node:

<xsl:template match="Object" mode="ancestors">
  <xsl:copy-of select="."/>
  <xsl:apply-templates select="key('by-id', @parent-id)" mode="ancestors"/>
</xsl:template>

and now invoke this for the selected items:

<xsl:template match="/">
 <root>
  <xsl:apply-templates select="root/Object[@status='0']" mode="ancestors"/>
 </root>
</xsl:template>

Not tested.