How to use xpointer with Xinclude to reference elements

Question

I want to merge 2 XML files with the same structure to make one. For example;

Test1.xml

<?xml version="1.0" encoding="UTF-8"?>

<ns:Root
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:ns="urn:TestNamespace"
    xsi:schemaLocation="urn:Test.Namespace Test1.xsd"
    >
    <ns:element1 id="001">
       <ns:element2 id="001.1" order="1">
           <ns:element3 id="001.1.1" />
       </ns:element2>
       <ns:element2 id="001.2" order="2">
           <ns:element3 id="001.1.2" />
       </ns:element2>
    </ns:element1>
</ns:Root>

and Test2.xml

<?xml version="1.0" encoding="UTF-8"?>

<ns:Root
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:ns="urn:TestNamespace"
    xsi:schemaLocation="urn:Test.Namespace Test1.xsd"
    >
    <ns:element1 id="999">
        <ns:element2 id="999.1" order="1">
            <ns:element3 id="999.1.1" />
        </ns:element2>
    </ns:element1>
</ns:Root>

To create

TestOutput.xml

<?xml version="1.0" encoding="UTF-8"?>

<ns:Root
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:ns="urn:TestNamespace"
    xsi:schemaLocation="urn:Test.Namespace Test1.xsd"
    >
    <ns:element1 id="001">
       <ns:element2 id="001.1" order="1">
           <ns:element3 id="001.1.1" />
       </ns:element2>
       <ns:element2 id="001.2" order="2">
           <ns:element3 id="001.1.2" />
       </ns:element2>
    </ns:element1>
    <ns:element1 id="999">
        <ns:element2 id="999.1" order="1">
            <ns:element3 id="999.1.1" />
        </ns:element2>
    </ns:element1>
</ns:Root>

ie one XML file with all the elements from each included.

I found a useful question on StackOverflow, and came up with this;

Merge.xml

<?xml version="1.0"?>

<ns:Root xmlns:xi="http://www.w3.org/2003/XInclude"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:ns="urn:TestNamespace">

    <xi:include href="Test1.xml" parse="xml" xpointer="element(//ns:Root/ns:element1)" />  

    <xi:include href="Test2.xml" parse="xml" xpointer="element(//ns:Root/ns:element1)" />

</ns:Root>

Which I run by doing this (I need to use xmllint for reasons to involved to go into)

xmllint -xinclude Merge.xml

But this does not work, it complains about various thiongs, which seem to relate to xpointer.

parser error : warning: ChildSeq not starting by /1
Merge.xml:7: element include: XInclude error : XPointer evaluation failed: #element(//ns:Root/ns:element1)
Merge.xml:7: element include: XInclude error : could not load Test1.xml, and no fallback was found
parser error : warning: ChildSeq not starting by /1
Merge.xml:9: element include: XInclude error : XPointer evaluation failed: #element(//ns:Root/ns:element1)
Merge.xml:9: element include: XInclude error : could not load Test2.xml, and no fallback was found
<?xml version="1.0"?>
<ns:Root xmlns:xi="http://www.w3.org/2003/XInclude" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ns="urn:TestNamespace">

    <xi:include href="Test1.xml" parse="xml" xpointer="element(//ns:Root/ns:element1)"/>

    <xi:include href="Test2.xml" parse="xml" xpointer="element(//ns:Root/ns:element1)"/>

</ns:Root>

If I omit the xpointer attributes in Merge.xml then I get some sensible output, but it has done more than include the elements I want of course.

Can someone offer some advice as to what I am doing wrong with xpointer please?

Thanks in antcipation.

Answer 1

I have dabbled with this a bit more, and found plenty of examples on the web that suggest what I am doing is correct.This is now a working version...

<?xml version="1.0"?>

<Root xmlns:xi="http://www.w3.org/2003/XInclude"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:ns="http://testurl.com/now">

    <xi:include href="Test1.xml" xpointer="xmlns(ns=http://testurl.com/now)xpointer(/ns:Root/ns:element1)" parse="xml" />
    <xi:include href="Test2.xml" xpointer="xpointer(//Root/element1)" parse="xml" />

</Root>

This example uses a version of Test1.xml which has namespaces, and Test2.xml which does not.

The output now looks like this....

<?xml version="1.0"?>
<Root xmlns:xi="http://www.w3.org/2003/XInclude" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ns="http://testurl.com/now">

    <ns:element1 xmlns:ns="http://testurl.com/now" id="001">
        <ns:element2 id="001.1" order="1">
            <ns:element3 id="001.1.1"/>
        </ns:element2>
        <ns:element2 id="001.2" order="2">
            <ns:element3 id="001.1.2"/>
        </ns:element2>
    </ns:element1><ns:element1 xmlns:ns="http://testurl.com/now" id="003">
        <ns:element2 id="007.0" order="1">
            <ns:element3 id="007.1.1"/>
        </ns:element2>
    </ns:element1><ns:element1 xmlns:ns="http://testurl.com/now" id="002">
        <ns:element2 id="002.1" order="3">
            <ns:element3 id="002.1.1"/>
        </ns:element2>
        <ns:element2 id="002.2" order="4">
            <ns:element3 id="002.1.2"/>
        </ns:element2>
    </ns:element1>
    <element1 id="999">
        <element2 id="999.1" order="1">
            <element3 id="999.1.1"/>
        </element2>
    </element1>

</Root>

This is of course acceptable, it would be nice if the line breaks between the open and close of element1 were still there

Answer 2

This works with and without namespaces:

<?xml version="1.0"?>
<ns:Root xmlns:xi="http://www.w3.org/2003/XInclude"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:ns="urn:TestNamespace">

    <xi:include href="Test1.xml" xpointer="xpointer(*/*)" />  
    <xi:include href="Test2.xml" xpointer="xpointer(*/*)" />

</ns:Root>

Also parse="xml" is default. You don't need to specify it.