Python XPath and ElementTree doesn't work if first XML parent tag is missing a child tag

Question

I'm currently using Python to convert a XML file to CSV format by using ElementTree library and XPath. My code works will if all of the child tag exists (First name, Last name, and address) for the first parent person tag, but I receive an error message of

Child Index out of range

when the first person is missing a child tag (only first and last name exist).

What code can I write to bypass this error message? This is my first time using XPath, how can an if statement be added to this? Or should I use something else?

Here's what my XML file looks like:

<?xml version="1.0" encoding="utf-8"?>
<Members>
    <Person>
      <FirstName>JANE</FirstName>
      <LastName>DOE</LastName>
    </Person>
    <Person>
      <FirstName>JOHN</FirstName>
      <LastName>DOE</LastName>
      <Address>
        <Address1>123 Straw Street</Address1>
        <Address2></Address2>
        <City>Apple</City>
        <State>Test</State>
        <ZipCode>123456    </ZipCode>
      </Address>
    </Person>
</Members>

Current Python Code:

import  csv
import xml.etree.ElementTree as ET

tree = ET.parse("TestStack.xml")
root = tree.getroot()

xml_data_to_csv =open('OutputStack.csv','w')

Csv_writer=csv.writer(xml_data_to_csv)
list_head=[]

count=0
for element in root.findall('Person'):
    person = []

    #Get head by tag
    if count == 0:
       FirstName = element.find('FirstName').tag
       list_head.append(FirstName)

       LastName = element.find('LastName').tag
       list_head.append(LastName)

       Address = element[2].tag
       list_head.append(Address)

       Csv_writer.writerow(list_head)
       count = count +1

    #get child node
    FirstName = element.find('FirstName').text
    person.append(FirstName)

    LastName = element.find('LastName').text
    person.append(LastName)

    person.append([e.text for e in element.findall('Address//')])

    #Write List_nodes to csv
    Csv_writer.writerow(person)
xml_data_to_csv.close()

It can be done with lxml, if you're interested.

Jack Fleeting
– Jack Fleeting

2019-06-05 19:23:47 +00:00
Commented Jun 5, 2019 at 19:23 — Jack Fleeting
– Jack Fleeting, Commented Jun 5, 2019 at 19:23

wp78de · Accepted Answer · 2019-06-05 21:31:28Z

1

I think the header should be predefined. I doubt that your CSV import backend accepts any format.

import  csv
import xml.etree.ElementTree as ET

tree = ET.parse("in.xml")
root = tree.getroot()

xml_data_to_csv =open('out.csv','w')

Csv_writer=csv.writer(xml_data_to_csv)
list_head=['FirstName', 'LastName', 'Address']
Csv_writer.writerow(list_head)

for element in root.findall('Person'):
    person = []

    #get child node
    FirstName = element.find('FirstName').text
    person.append(FirstName)

    LastName = element.find('LastName').text
    person.append(LastName)

    person.append([e.text for e in element.findall('Address//')])

    #Write List_nodes to csv
    Csv_writer.writerow(person)
xml_data_to_csv.close()

Otherwise, you could either handle the exception or check how many elements exist like this

if len(element) > 2:
    head_list.append(element[2])
    continue

Preinitialize the head_list = [None] * 3 #len(element), and collect the headers (as the show-up) and persons during the for-loop, then write everything at the end. I would not recommend that route.

answered Jun 5, 2019 at 21:31

wp78de

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3 Comments

Codr4Life Over a year ago

Thanks wp78de, you're a genius! That worked perfectly!

Codr4Life Over a year ago

how did you know that tags in the head_list would work?

wp78de Over a year ago

@Codr4Life I just figured how I would code this any language - sometimes Python is too slick.

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