Modify XML file using ElementTree

Question

I am trying to do the folowing with Python:

get "price" value and change it
find "price_qty" and insert new line with new tier and different price based on the "price".
so far I could only find the price and change it and insert line in about correct place but I can't find a way how to get there "item" and "qty" and "price" attributes, nothing has worked so far...

this is my original xml:

     <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
    <body start="20.04.2014 10:02:60">
        <pricelist>
            <item>
              <name>LEO - red pen</name>
              <price>31,4</price>
              <price_snc>0</price_snc>
              <price_ao>0</price_ao>
              <price_qty>
                <item qty="150" price="28.20" />
                <item qty="750" price="26.80" />
                <item qty="1500" price="25.60" />
               </price_qty>
            <stock>50</stock>
            </item>
        </pricelist>

the new xml should look this way:

    <pricelist>
    <item>
      <name>LEO - red pen</name>
      <price>31,4</price>
      <price_snc>0</price_snc>
      <price_ao>0</price_ao>
      <price_qty>
        <item qty="10" price="31.20" /> **-this is the new line**
        <item qty="150" price="28.20" />
        <item qty="750" price="26.80" />
        <item qty="1500" price="25.60" />
       </price_qty>
    <stock>50</stock>
    </item>
</pricelist>

my code so far:

import xml.etree.cElementTree as ET
from xml.etree.ElementTree import Element, SubElement

tree = ET.ElementTree(file='pricelist.xml')
root = tree.getroot()
pos=0

# price - raise the main price and insert new tier
for elem in tree.iterfind('pricelist/item/price'):
    price = elem.text
    newprice = (float(price.replace(",", ".")))*1.2    

    newtier = "NEW TIER" 
    SubElement(root[0][pos][5], newtier)
    pos+=1

tree.write('pricelist.xml', "UTF-8")

result:

...
 <price_qty>
        <item price="28.20" qty="150" />
        <item price="26.80" qty="750" />
        <item price="25.60" qty="1500" />
      <NEW TIER /></price_qty>

thank you for any help.

we want to insert <item qty="10" price="31.20" /> as first child of <price_qty> tag ??? — Vivek Sable
– Vivek Sable, Commented Feb 28, 2015 at 14:40

Daniel · Accepted Answer · 2015-02-28 15:09:41Z

3

Don't use fixed indexing. You already have the item element, so why don't use it?

tree = ET.ElementTree(file='pricelist.xml')
root = tree.getroot()

for elem in tree.iterfind('pricelist/item'):
    price = elem.findtext('price')
    newprice = float(price.replace(",", ".")) * 1.2

    newtier = ET.Element("item", qty="10", price="%.2f" % newprice)
    elem.find('price_qty').insert(0, newtier)

tree.write('pricelist.xml', "UTF-8")

answered Feb 28, 2015 at 15:09

Daniel

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3 Comments

Jan Kyselák Over a year ago

that looks like exactly what I need, but for some reason I am getting - AttributeError: 'NoneType' object has no attribute 'insert'. do you have idea where to look or what to try ? thank you !

Jan Kyselák Over a year ago

it seems like it doesn't find the element, if I use the fixed indexing it works, but it stays on the same line as the first one (don't know if is it problem).

Jan Kyselák Over a year ago

I have opened new question with the fixed indexing problem as I can insert what I need (thank you) but only using fixed indexing that you mention and it brings the problem that in some part of the xml I get off index: link

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