Merging Lots Of XML Files

I have lots of xml files that I need to merge. I have tried this link at merging xml files using python's ElementTree whose code is (Edited as per my need): import os, os.path, sys

Solution 1:

Consider using XSLT and its document() function to merge XML files. Python (like many object-oriented programming languages) maintain an XSLT processor like in its lxml module. As information, XSLT is a declarative programming language to transform XML files in various formats and structures.

For your purposes, XSLT may be more efficient than using programming code to develop files as no lists or loops or other objects are held in memory during processing except what the XSLT processor would use.

XSLT (to be saved externally as .xsl file)

Consider initially running a Python write to text file looping to fill in all 365 documents to avoid copy and paste. Also notice first document is skipped since it is the starting point used in Python script below:

<?xml version="1.0" ?> 
<xsl:transform xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"> 

 <xsl:template match="DATA">
  <DATA>
    <xsl:copy> 
       <xsl:copy-of select="TALLYMESSAGE"/>
       <xsl:copy-of select="document('Document2.xml')/BODY/DATA/TALLYMESSAGE"/>
       <xsl:copy-of select="document('Document3.xml')/BODY/DATA/TALLYMESSAGE"/>
       <xsl:copy-of select="document('Document4.xml')/BODY/DATA/TALLYMESSAGE"/>
       ...
       <xsl:copy-of select="document('Document365.xml')/BODY/DATA/TALLYMESSAGE"/>             
    </xsl:copy>
  </DATA>
 </xsl:template> 

</xsl:transform>

Python (to be included in you overall script)

import lxml.etree as ET

dom = ET.parse('C:\Path\To\XML\Document1.xml')
xslt = ET.parse('C:\Path\To\XSL\file.xsl')
transform = ET.XSLT(xslt)
newdom = transform(dom)

tree_out = ET.tostring(newdom, encoding='UTF-8', pretty_print=True,  xml_declaration=True)
print(tree_out)

xmlfile = open('C:\Path\To\XML\OutputFile.xml','wb')
xmlfile.write(tree_out)
xmlfile.close()