Question

Hello I am having trouble with a xml file I am using. Now what happens is on a short xml file the program works fine but for some reason once it reaches a size ( I am thinking 1 MB)
it gives me a “IndexError: list index out of range”

Here is the code I am writing so far.

from xml.dom import minidom

import smtplib
from email.mime.text import MIMEText
from datetime import datetime

def xml_data():
    f = open('C:\opidea_2.xml', 'r')
    data = f.read()
    f.close()

    dom = minidom.parseString(data)
    ic = (dom.getElementsByTagName('logentry'))
    dom = None      
    content = ''  

    for num in ic:
        name = num.getElementsByTagName('author')[0].firstChild.nodeValue
        if name:
            content += "***Changes by:"  + str(name) + "*** " +  '\n\n     Date: '
        else:
            content += "***Changes are made Anonymously *** " +  '\n\n     Date: '
        print content

if __name__ == "__main__":
    xml_data ()

Here is part of the xml if it helps.

 <log>
 <logentry
  revision="33185">
 <author>glv</author>
 <date>2012-08-06T21:01:52.494219Z</date>
 <paths>

 <path
  kind="file"
  action="M">/branches/Patch_4_2_0_Branch/text.xml</path>   

 <path
  kind="dir"
  action="M">/branches/Patch_4_2_0_Branch</path>

</paths>
<msg>PATCH_BRANCH:N/A
 BUG_NUMBER:N/A
 FEATURE_AFFECTED:N/A
 OVERVIEW:N/A
  Adding the SVN log size requirement to the branch 
 </msg>
  </logentry>
    </log>

The actual xml file is much bigger but this is the general format. It will actually work if it was this small but once it gets bigger I get problems.

here is the traceback

Traceback (most recent call last):
  File "C:\python\src\SVN_Email_copy.py", line 141, in <module>
    xml_data ()
  File "C:\python\src\SVN_Email_copy.py", line 50, in xml_data
    name = num.getElementsByTagName('author')[0].firstChild.nodeValue
IndexError: list index out of range

Answer 1

Based on the code provided your error is going to be in this line:

name = num.getElementsByTagName('author')[0].firstChild.nodeValue
#xml node-^
#function call -------------------------^
#list indexing ----------------------------^
#attribute access -------------------------------------^

That’s the only place in the demonstrated code that you’re indexing into a list. That would imply that in your larger XML Sample you’re missing an <author> tag. You’ll have to correct that, or add in some level of error handling / data validation.

Please see the code elaboration for more explanation. You’re doing a ton of things in a single line by taking advantage of the return behaviors of successive commands. So, the num is defined, that’s fine. Then you call a function (method). It returns a list. You attempt to retrieve from that list and it throws an exception, so you never make it to the Attribute Access to get to firstChild, which definitely means you get no nodeValue.

Error checking may look something like this:

authors = num.getElementsByTagName('author')
if len(authors) > 0:
  name = authors[0].firstChild.nodeValue

Though there are many, many ways you could achieve that.