Sort multiple XML files by dates and combine them into one with XSLT

Question

I have several separate XML files containing historical letters in TEI. Now I want to combine them into one file with a date as criteria.

A1.xml

<?xml version="1.0" encoding="UTF-8"?>
<TEI xml:id="1">
<teiHeader>
    <title>Letter 1</title>
    <date when="19990202" n="0"></date>
</teiHeader>
<text>
        <p>Content of letter 1</p>
</text>
</TEI>

and the second file, A2.xml:

<?xml version="1.0" encoding="UTF-8"?>
    <TEI xml:id="2">
    <teiHeader>
        <title>Letter 1</title>
        <date when="20010202" n="0"></date>
    </teiHeader>
    <text>
            <p>Content of letter 2</p>
    </text>
    </TEI>

and third, A3.xml:

<?xml version="1.0" encoding="UTF-8"?>
    <TEI xml:id="3">
    <teiHeader>
        <title>Letter 3</title>
        <date when="18880101" n="0"></date>
    </teiHeader>
    <text>
            <p>Content of letter 3</p>
    </text>
    </TEI>

Files are named in sequential file names "A001.xml" to "A999.xml", but not in the desired order. Therefore, my preferred output would be a single letter.xml file:

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

<TEI xml:id="3">
        <teiHeader>
            <title>Letter 3</title>
            <date when="18880101" n="0"></date>
        </teiHeader>
        <text>
                <p>Content of letter 3</p>
        </text>
        </TEI>

    <TEI xml:id="1">
    <teiHeader>
        <title>Letter 1</title>
        <date when="19990202" n="0"></date>
    </teiHeader>
    <text>
            <p>Content of letter 1</p>
    </text>
    </TEI>
        <TEI xml:id="2">
        <teiHeader>
            <title>Letter 1</title>
            <date when="20010202" n="0"></date>
        </teiHeader>
        <text>
                <p>Content of letter 2</p>
        </text>
        </TEI>
</CORRESPONDENCE>

Even if I find ways to merge several XML files into one, I can’t get it working using the sorting criteria. Is it possible?

Answer 1

XML- Saxon 9 XSLT 2.0, ,

<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:param name="file-suffix" as="xs:string" select="'A*.xml'"/>

<xsl:template match="/" name="main">
  <CORRESPONDENCE>
    <xsl:perform-sort select="collection(concat('.?select=', $file-suffix))/*">
      <xsl:sort select="teiHeader/date/xs:integer(@when)"/>
    </xsl:perform-sort>
  </CORRESPONDENCE>
</xsl:template>

</xsl:stylesheet>

-it:main -xsl:stylesheet.xsl , , , , , collection, .

http://www.tei-c.org/ns/1.0, ,

<xsl:stylesheet
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  xpath-default-namespace="http://www.tei-c.org/ns/1.0"
  exclude-result-prefixes="xs"
  version="2.0">

<xsl:param name="file-suffix" as="xs:string" select="'A*.xml'"/>

<xsl:template match="/" name="main">
  <CORRESPONDENCE>
    <xsl:perform-sort select="collection(concat('.?select=', $file-suffix))/*">
      <xsl:sort select="teiHeader/date/xs:integer(@when)"/>
    </xsl:perform-sort>
  </CORRESPONDENCE>
</xsl:template>

</xsl:stylesheet>

Answer 2

?

XSLT XML , Turing , , , .

XSLT 3.0, : xsl:merge. , . , ( ).

XSLT 3.0 xsl:merge

, XML , .

<!-- xsl:initial-template, new in XSLT 3.0 is like "int main()" in C-style languages -->
<xsl:template name="xsl:initial-template">
    <!-- your other code here -->
    <result>
        <xsl:merge>

            <!-- 
            xsl:merge defines the source for merging. It is quite powerful. Here
            is a simple example with your data.

            With for-each-item you select a sequence of items that need to be merged,
            which goes in two steps, first you select a list of anchor items, then
            you use the select-attribute to select the sequence you want to merge. Here 
            a collection of documents is requested, like in OP question

            The select statement selects, with focus on each document, the sequence
            of items to be merged. This sequence can be of any length (here it selects all
            historic letters)

            The merge-key defines the key for which items in the merge sequence are sorted,
            an incorrect order will result in an error, unless sort-before-merge 
            is also specified.
            -->
            <xsl:merge-source 
                for-each-item="collection('files/A*.xml')"
                select="/root/historic-letter/tei:TEI"
                sort-before-merge="true">
                <xsl:merge-key 
                    select="tei:teiHeader/tei:data/tei:when"
                    order="descending" 
                    data-type="number" />
            </xsl:merge-source>

            <!-- the merge action is called for each item resulting from the select 
            statement above. Only in this place can you use current-merge-key()
            and the current-merge-group() functions, which work similar to their grouping
            counterparts.
            -->
            <xsl:merge-action>
                <source original-document="{base-uri()}">
                    <xsl:copy-of select="." />
                </source>
            </xsl:merge-action>
        </xsl:merge>
    </result>
</xsl:template>