Including an XML file in an XML/XSL file

I. Here is how any XML document or fragment can be embedded in an XSLT stylesheet and used during the transformation:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
 xmlns:my="my:my">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>
 <xsl:strip-space elements="*"/>

 <my:menu>
   <menu>
     <choice>A</choice>
     <choice>B</choice>
     <choice>C</choice>
   </menu>
 </my:menu>

 <xsl:template match="/">
  <xsl:copy-of select="document('')/*/my:menu/*"/>
 </xsl:template>
</xsl:stylesheet>

When this transformation is applied on any XML document (not used in this example), the wanted result (just copying the XML) is produced:

<menu xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:my="my:my">
   <choice>A</choice>
   <choice>B</choice>
   <choice>C</choice>
</menu>

Remember: Any XML can be embedded into an XSLT stylesheet, provided it is wrapped into a namespaced element (the namespace not the XSLT namespace) and this wrapping element is at the global level (a child of the <xsl:stylesheet> (top) element).

II. Accessing the XML menu file that resides in a separate XML file:

To do this we have to change only slightly the previous example:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>
 <xsl:strip-space elements="*"/>


 <xsl:template match="/">
  <xsl:copy-of select="document('menu.XML')/*"/>
 </xsl:template>
</xsl:stylesheet>

If the menu XML file is in the 'menu.XML' file (in the same directory as the XSLT stylesheet file, then this transformation produces exactly the same result as the previous:

<menu>
   <choice>A</choice>
   <choice>B</choice>
   <choice>C</choice>
</menu>

Do note: In both cases we are using the standard XSLT function document()

Typically, one defines a global-level variable, whose value is the result of calling the document() function. Then this variable and its contents is accessed via XPath expressions during the transformation.

I have a blog post on this. You use document() to get the other XML and pass around the content using parameters.

So, how do I include an XML file in to another XML file or in to a XSL file?

You can use an external entity to reference the menu.xml file and include the content into either an XML file or the XSLT (or both).

By include, I mean referencing/loading it from another file, not copy and pasting it or simply embedding it.

By using external entities, you can reference/load the menu.xml content from external files and do not have to duplicate the XML content.

For instance, if you wanted the menu.xml content included in your XSLT, you would declare the external entity in your XSLT like this:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE stylesheet [
     <!ENTITY menu SYSTEM "./menu.xml">
]>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

and could then reference it like you would any other entity:

&menu;

When the XSLT parsed, the entity reference will be expanded and the XML content of the menu.xml will be included as part of the XSLT document as if you had copy/pasted into the spot where the entity reference was.