xslt to group xml based on element values - xslt

Question

want to group request based on similar package id using manual XSLT
Here is input xml which contains plan_id on which it needs to be grouped
<subscriptions>
<package>
<package_plan>
<plan_id>1111</plan_id>
<plan_name>economy1</plan_name>
</package_plan>
<rate_channel>
<rateid>1F1</rateid>
<currency>USD</currency>
<package_duration>monthly</package_duration>
<price>3</price>
</rate_channel>
</package>
<package>
<package_plan>
<plan_id>1111</plan_id>
<plan_name>economy1</plan_name>
</package_plan>
<rate_channel>
<rateid>1F2</rateid>
<currency>USD</currency>
<package_duration>quaterly</package_duration>
<price>11</price>
</rate_channel>
</package>
<package>
<package_plan>
<plan_id>2222</plan_id>
<plan_name>economy2</plan_name>
</package_plan>
<rate_channel>
<rateid>1F3</rateid>
<currency>INR</currency>
<package_duration>monthly</package_duration>
<price>250</price>
</rate_channel>
</package>
</subscriptions>
Looking for output as:
<subscriptions>
<package>
<plan_id>1111</plan_id>
<plan_name>economy1</plan_name>
<channels>
<rate_channel>
<rateid>1F1</rateid>
<currency>USD</currency>
<package_duration>monthly</package_duration>
<price>3</price>
</rate_channel>
<rate_channel>
<rateid>1F2</rateid>
<currency>USD</currency>
<package_duration>quaterly</package_duration>
<price>11</price>
</rate_channel>
</channels>
</package>
<package>
<plan_id>2222</plan_id>
<plan_name>economy2</plan_name>
<channels>
<rate_channel>
<rateid>1F3</rateid>
<currency>INR</currency>
<package_duration>monthly</package_duration>
<price>250</price>
</rate_channel>
</channels>
</package>
</subscriptions>
I've been doing some search and reading the other posts, and I don't think they cover exactly what I want to do
Thanks in advance...

Answer 1

Below are the XSLT 1.0 and XSLT 2.0 solutions. Both the solutions use a different approach as rightly pointed by #Tim C in the comment.
XSLT 1.0
In case of XSLT 1.0, muenchian grouping is used. A <xsl:key> needs to be defined to group the elements. In this case, <plan_id> is the key on which the grouping will be done.
<xsl:key name="plan" match="package" use="package_plan/plan_id" />
The package elements are matched accordingly and the grouped data is copied to the output.
<xsl:template match="package[generate-id() = generate-id(key('plan', package_plan/plan_id)[1])]">
<xsl:copy>
<xsl:variable name="varPlan" select="key('plan', package_plan/plan_id)" />
<xsl:apply-templates select="$varPlan[1]/package_plan/plan_id" />
<xsl:apply-templates select="$varPlan[1]/package_plan/plan_name" />
<channels>
<xsl:for-each select="$varPlan">
<xsl:apply-templates select="rate_channel" />
</xsl:for-each>
</channels>
</xsl:copy>
</xsl:template>
The rest of the <package> elements are removed.
<xsl:template match="package" />
XSLT 2.0
In XSLT 2.0, <xsl-for-each-group> feature is available especially for grouping of elements. In this case, using this feature and the current-group() function, grouping can be achieved.
<xsl:template match="subscriptions">
<xsl:copy>
<xsl:for-each-group select="package" group-by="package_plan/plan_id">
<package>
<xsl:apply-templates select="current-group()[1]/package_plan/plan_id" />
<xsl:apply-templates select="current-group()[1]/package_plan/plan_name" />
<channels>
<xsl:for-each select="current-group()">
<xsl:apply-templates select="rate_channel" />
</xsl:for-each>
</channels>
</package>
</xsl:for-each-group>
</xsl:copy>
</xsl:template>
In both the above cases, an identity transform template should be used to copy the data as is to the output.
<xsl:template match="#* | node()">
<xsl:copy>
<xsl:apply-templates select="#* | node()" />
</xsl:copy>
</xsl:template>