Question

XSLT 2 is preferred and I hope makes this easier.

Given a document similar to

<doc xmlns:bob="bob.com">
    <element bob:name="fred" bob:occupation="Dr">Stuff</element>
    <element bob:name="Bill" bob:occupation="Dr" bob:birthMonth="Jan"/>
    <element>Kill Me</element>
    <element bob:name="fred" bob:occupation="Dr">different Stuff</element>
</doc>

I would like to have all of the unique elements based on all the attributes in bob namespace. This is a representative sample but I will have much deeper nesting so all I want it to traverse the tree for

*[@bob:*] and get the unique set of those.

The hoped for output would look like

<doc xmlns:bob="bob.com">
    <element bob:name="fred" bob:occupation="Dr">Stuff</element>
    <element bob:name="Bill" bob:occupation="Dr" bob:birthMonth="Jan"/>
</doc>

where one element was removed for not having any @bob:* attributes and the other was removed for being a duplicate of the first based solely on the attributes.

I was trying to use a key but didn’t seem to be doing it right

<xsl:key name="BobAttributes" match="//*" use="./@bob:*" />

I also tried creating a function that concatenated all the @bob attributes but that also didn’t seem to do what I hoped.

<xsl:key name="BobAttributes" match="//*" use="functx:AllBobConcat(.)" />

 <xsl:function name="functx:AllBobConcat" as="xs:string*" 
    xmlns:functx="http://www.functx.com" >
    <xsl:param name="nodes" as="node()*"/> 

    <xsl:for-each select="$nodes/@bob:*">
        <xsl:value-of select="local-name(.)"/>
        <xsl:value-of select="."/>
    </xsl:for-each>
</xsl:function>

In both cases I was using “simple” XSL to filter out the unique ones maybe I blew it here?
Variables added here to try and debug.

  <xsl:template match="*[@ism:*]" priority="100">
        <xsl:variable name="concat">
            <xsl:value-of select="functx:AllBobConcat(.)"/>
        </xsl:variable>

        <xsl:variable name="myID">
            <xsl:value-of select="generate-id() "/>
        </xsl:variable>

        <xsl:variable name="Keylookup">
            <xsl:value-of select="key('BobAttributes', $concat)"/>
        </xsl:variable>
        <xsl:value-of select="concat($concat, $Keylookup, $myID)"/>
        <xsl:if test="generate-id() = generate-id(key('BobAttributes', $concat)[1])">

            <xsl:apply-templates select="." mode="copy"/>
        </xsl:if>
    </xsl:template>

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

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

Looking forward to hearing what simple thing I overlooked or completely different cool approach I should have taken.

Answer 1

I would define the function AllBobConcat as you do, and then use this as a grouping key:

<xsl:for-each-group select="element" group-by="f:AllBobConcat(.)">
  <xsl:if test="current-grouping-key() != ''">
    <xsl:copy-of select="current-group()[1]"/>
  </xsl:if>
</xsl:for-each-group>

Except that AllBobConcat needs to ensure the attributes are in a canonical order, so:

<xsl:function name="f:AllBobConcat" as="xs:string">
    <xsl:param name="node" as="element(element)"/> 
    <xsl:value-of>
      <xsl:for-each select="$node/@bob:*">
        <xsl:sort select="local-name()"/>
        <xsl:value-of select="local-name(.)"/>
        <xsl:value-of select="'='"/>
        <xsl:value-of select="."/>
        <xsl:value-of select="' '"/>
      </xsl:for-each>
    </xsl:value-of>
</xsl:function>

Also, you shouldn’t be putting your functions in a namespace that belongs to someone else.