Modifying XML file using python (klish types.xml)

Question

The following is the original xml file.

<?xml version="1.0" encoding="UTF-8"?>
<CLISH_MODULE xmlns="http://clish.sourceforge.net/XMLSchema" 
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
 xsi:schemaLocation="http://clish.sourceforge.net/XMLSchema
                     http://clish.sourceforge.net/XMLSchema/clish.xsd">
    <!--=======================================================-->
    <PTYPE name="VLAN_ID" 
        pattern="(409[0-5]|40[0-8][0-9]|[1-3][0-9]{3}|[1-9][0-9]{2}|[1-9][0-9]|[1-9])"
        help="Number in the range 1-4095"/>
    <!--=======================================================-->
    <PTYPE name="MYFIELD"
        pattern="0..99"
        help="Entry number"/>
    <!--=======================================================-->
</CLISH_MODULE>

Here is the python code to modify xml file

import xml.etree.ElementTree as ET

tree = ET.parse('testxml.xml')
ET.register_namespace('', "http://clish.sourceforge.net/XMLSchema")
root = tree.getroot()

for child in root:
    for key, value in child.items():
        if value == "MYFIELD":
            print value
            child.attrib['pattern'] = '1..55'

tree.write('testxml.xml', encoding="UTF-8")

Here is the resulted xml file.

<?xml version='1.0' encoding='UTF-8'?>
<CLISH_MODULE xmlns="http://clish.sourceforge.net/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://clish.sourceforge.net/XMLSchema                      http://clish.sourceforge.net/XMLSchema/clish.xsd">

        <PTYPE help="Number in the range 1-4095" name="VLAN_ID" pattern="(409[0-5]|40[0-8][0-9]|[1-3][0-9]{3}|[1-9][0-9]{2}|[1-9][0-9]|[1-9])" />  

        <PTYPE help="Entry number" name="MYFIELD" pattern="1..55" />



</CLISH_MODULE>

I'm able to modify the content but there is a problem in preserving the format. Can you please share the knowledge about how to fix this issue.

Answer 1

After trying lot of things, tried this way by parsing the input file and making the change where the attribute and it's value matches

  if value == "MYFIELD":        
                fin = open("testxml.xml")
                fout = open("testx.xml", "wt")
                for line in fin:
                    xm= 'pattern="'+child.attrib['pattern']+'"'
                    fout.write( line.replace(xm, 'pattern="1..55"') )

OutPut

<?xml version="1.0" encoding="UTF-8"?>
<CLISH_MODULE xmlns="http://clish.sourceforge.net/XMLSchema" 
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
 xsi:schemaLocation="http://clish.sourceforge.net/XMLSchema
                     http://clish.sourceforge.net/XMLSchema/clish.xsd">
    <!--=======================================================-->
    <PTYPE name="VLAN_ID" 
        pattern="(409[0-5]|40[0-8][0-9]|[1-3][0-9]{3}|[1-9][0-9]{2}|[1-9][0-9]|[1-9])"
        help="Number in the range 1-4095"/>
    <!--=======================================================-->
    <PTYPE name="MYFIELD"
        pattern="1..55"
        help="Entry number"/>
    <!--=======================================================-->
</CLISH_MODULE>

not a best solution , but gives the result as expected