How to use group-by functionality from XSLT 2.0 in XSLT 1.0?

Question

I am trying to use the group-by functionality in XSLT 2.0 in XSLT 1.0. I have code working in XSLT 2.0 but my processor does not handle xslt 2.0. So i need some help using the group-by function in xslt 1.0.

XML data:

              <table>
                <row>
                    <month>03</month>
                    <year>2016</year>
                    <Id>10101</Id>
                    <Number>1</Number>
                    <code>A2004</code>
                </row>
                <row>
                    <month>03</month>
                    <year>2016</year>
                    <type>A</type>
                    <Id>10101</Id>
                    <Number>2</Number>
                    <code>A2004</code>
                </row>
                <row>
                    <month>04</month>
                    <year>2015</year>
                    <Id>10122</Id>
                    <Number>1</Number>
                    <code>A2004</code>
                </row>
            </table>

I am trying to group this xml on the ID level and the numbers within it.

            <test>
                <xsl:for-each-group select="$table" group-by="Id">
                    <xsl:variable name="var2_resultof_group_items" as="item()+" select="current-group()"/>
                    </xsl:variable>
                    <row>
                        <xsl:attribute name="Id">
                            <xsl:value-of select="normalize-space(current-grouping-key())"/>
                        </xsl:attribute>
                        <xsl:for-each select="$var2_resultof_group_items">
                            <xsl:attribute name="month">
                                <xsl:value-of select="month"/>
                            </xsl:attribute>
                        </xsl:for-each>
                        <xsl:for-each select="$var2_resultof_group_items">
                            <xsl:attribute name="year">
                                <xsl:value-of select="year"/>
                            </xsl:attribute>
                        </xsl:for-each>
                        <xsl:for-each-group select="$var2_resultof_group_items" group-by="Number">
                            <xsl:variable name="var1_resultof_group_items" as="item()+" select="current-group()"/>
                            <line>
                                <xsl:attribute name="number" select="current-grouping-key()"/>
                                <xsl:for-each select="$var1_resultof_group_items">
                                    <xsl:attribute name="code">
                                        <xsl:value-of select="code"/>
                                    </xsl:attribute>
                                </xsl:for-each>
                            </line>
                        </xsl:for-each-group>
                    </row>
                </xsl:for-each-group>
            </test>

This is the output i am getting with my xslt 2.0 code (desired output) but i am not sure how to perform this using xslt 1.0

            <test>
                <row Id="10101" month="03" year="2016">
                    <line Number="1" code="A2004"/>
                    <line Number="2" code="A2004"/>
                </row>
                <row Id="10122" month="04" year="2015">
                    <line Number="1" code="A2004"/>
                </row>
            </test>

I am able to use XLST 1.0 to get till the output below, but i am not sure how to implement grouping of ID and then the Numbers within it:

            <test>
                <row Id="10101" month="03" year="2016">
                    <line Number="1" code="A2004"/>
                </row>
                <row Id="10101" month="03" year="2016">
                    <line Number="2" code="A2004"/>
                </row>
                <row Id="10122" month="04" year="2015">
                    <line Number="1" code="A2004"/>
                </row>
            </test>

Answer 1

You may try this muenchian grouping XSLT 1.0 solution:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" indent="yes"/>
    <xsl:key name="kid" match="row" use="Id"/>
     <xsl:template match="table">
        <test>
            <xsl:for-each select="row [ 
                                count ( key('kid',./Id)[1] | . ) = 1 ]">

                <xsl:variable name="this" select="."/>
                <row>
                    <xsl:attribute name="Id">
                      <xsl:value-of select="Id"/>
                    </xsl:attribute>
                    <xsl:attribute name="month">
                      <xsl:value-of select="month"/>
                    </xsl:attribute>
                    <xsl:attribute name="year">
                        <xsl:value-of select="year"/>
                    </xsl:attribute>
                    <xsl:for-each select="key('kid', $this/Id)">
                        <line>
                           <xsl:attribute name="number" >
                               <xsl:value-of  select="Number"/>
                           </xsl:attribute>
                            <xsl:attribute name="code">
                               <xsl:value-of select="code"/>
                            </xsl:attribute>
                        </line>
                    </xsl:for-each>
              </row>
          </xsl:for-each>
        </test>
    </xsl:template>
</xsl:stylesheet>

With following output:

<test>
  <row Id="10101" month="03" year="2016">
    <line number="1" code="A2004"/>
    <line number="2" code="A2004"/>
  </row>
  <row Id="10122" month="04" year="2015">
    <line number="1" code="A2004"/>
  </row>
</test>

Answer 2

Here is a much simpler, shorter and almost completely in "push" style solution:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>
 <xsl:key name="kRowById" match="row" use="Id"/>

  <xsl:template match="/*">
    <test>
      <xsl:apply-templates/>
    </test>
  </xsl:template>

  <xsl:template match="row[generate-id() = generate-id(key('kRowById', Id)[1])]">
    <row id="{Id}">
      <xsl:apply-templates select="key('kRowById', Id)" mode="inGroup"/>
    </row>
  </xsl:template>

  <xsl:template match="row" mode="inGroup">
    <line Number="{Number}" code="{code}"/>
  </xsl:template>
  <xsl:template match="text()"/>
</xsl:stylesheet>

When this transformation is applied on the provided XML document:

<table>
    <row>
        <month>03</month>
        <year>2016</year>
        <Id>10101</Id>
        <Number>1</Number>
        <code>A2004</code>
    </row>
    <row>
        <month>03</month>
        <year>2016</year>
        <type>A</type>
        <Id>10101</Id>
        <Number>2</Number>
        <code>A2004</code>
    </row>
    <row>
        <month>04</month>
        <year>2015</year>
        <Id>10122</Id>
        <Number>1</Number>
        <code>A2004</code>
    </row>
</table>

the wanted, correct result is produced:

<test>
   <row id="10101">
      <line Number="1" code="A2004"/>
      <line Number="2" code="A2004"/>
   </row>
   <row id="10122">
      <line Number="1" code="A2004"/>
   </row>
</test>

Explanation:

1. Muenchian grouping.

2. Using the standard XSLT function generate-id() for node identity comparison.

3. Using AVT (Attribute-Value Templates)

4. Using modes.

5. Using the XSLT built-in (aka "default") templates.