XSLT- Creating Parent XML element - xslt

Question

I've fairly recently started learning XSLT after getting to grips with XML and XPath; I'm trying to complete a practice exercise; I think I'm nearly there but I've ran into a problem. So I have the following XML document:
<?xml version="1.0" encoding="UTF-8"?>
<root>
<a>
<b></b>
<b></b>
<b></b>
<b></b>
</a>
</root>
And I'd like to surround the elements with a pair of parent elements (to output the following):
<?xml version="1.0" encoding="UTF-8"?>
<root>
<a>
<b-group>
<b></b>
<b></b>
<b></b>
<b></b>
<b-group>
</a>
Here is my XSLT:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
exclude-result-prefixes="xs"
version="2.0">
<xsl:template match="root">
<xsl:element name="root">
<xsl:apply-templates select="#*|node()"/>
</xsl:element>
</xsl:template>
<xsl:template match="a">
<xsl:element name="a">
<xsl:apply-templates select="#*|node()"/>
</xsl:element>
</xsl:template>
<xsl:template match="b">
<xsl:element name="b-group">
<xsl:apply-templates select="#*|node()"/>
</xsl:element>
</xsl:template>
<xsl:template match="b">
<xsl:element name="b">
<xsl:apply-templates select="#*|node()"/>
</xsl:element>
</xsl:template>
</xsl:stylesheet>
Despite making several other attempts, I'm having difficulty creating the pair of elements that surround the elements; could anyone point me in the right direction of how to do this please?

Answer 1

You need to do this in the template matching a, for example:
<xsl:template match="a">
<a>
<b-group>
<xsl:apply-templates select="b"/>
</b-group>
</a>
</xsl:template>
Additional notes:
Use a literal result element to create an element whose name is known, instead of xsl:element.
Most of your templates do the same thing: create an element with the same name as the one being matched, and apply templates to its children. Thus they could be consolidated into one. A template like this is known as the identity transform template and it is commonly used when most of the document needs to preserved as is, with only a few modifications. This would reduce your entire stylesheet to just:
<xsl:stylesheet version="2.0"
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="*"/>
<!-- identity transform -->
<xsl:template match="#*|node()">
<xsl:copy>
<xsl:apply-templates select="#*|node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="a">
<a>
<b-group>
<xsl:apply-templates select="b"/>
</b-group>
</a>
</xsl:template>
</xsl:stylesheet>