Python Parsing nested XML and flattening the data

This can easily be solved using XSLT without introducing Python in your workflow, however, if you have to use Python, lxml.etree conveniently introduced a new class lxml.etree.XSLT which you can exploit to your advantage.

Assuming your XML data is in a file named xmlfile.xml the code below should work.

xsltfile.xsl

<?xml version="1.0" encoding="utf-8" ?>
<xsl:stylesheet version="1.0"
        xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
        <xsl:output method="text" />
        <xsl:template match="SalC">
                <xsl:value-of select="concat(../@col1,',', ../@col2,',',../@col3,',',../@col4,',',../@col5,',',../@col6,',',@col7,',',@col8,',',@col9,',',@col10)" />
        </xsl:template>
</xsl:stylesheet>

Example Code

from lxml import etree

xsltfile = etree.XSLT(etree.parse('xsltfile.xsl'))
xmlfile = etree.parse('xmlfile.xml')
output = xsltfile(xmlfile)
print(output)

sal.attrib is dict-like:

row = dict(sal.attrib)

salc.attrib is also dict-like. To "flatten" -- or rather, join -- the two dicts togther, you could use dict.update:

row.update(salc.attrib)

Assuming each SalC element has col7, col8, cal9 and col10 attributes, you can just call row.update(salc.attrib) for each salc in sal:

import lxml.etree as ET
import csv

text = '''\
<root>
<Sal col1="a1" col2="C" col3="12/5/2012" col4="a" col5="8" col6="True">
    <SalC col7="A" col8="1" col9="2" col10="True"/>
...
    <SalC col7="D" col8="1" col9="2" col10="True"/>
    <SalC col7="E" col8="1" col9="2" col10="False"/>
</Sal>
</root>'''

fieldnames = ('col1', 'col2', 'col3', 'col4', 'col5', 'col6', 'col6', 'col7', 'col8', 
              'col9', 'col10')

with open('/tmp/output.csv', 'wb') as f:
    writer = csv.DictWriter(f, fieldnames, delimiter = ',', lineterminator = '\n', )
    writer.writeheader()
    root = ET.fromstring(text)
    for sal in root.xpath('//Sal'):
        row = dict(sal.attrib)
        for salc in sal:
            row.update(salc.attrib)
            writer.writerow(row)

yields

col1,col2,col3,col4,col5,col6,col6,col7,col8,col9,col10
a1,C,12/5/2012,a,8,True,True,A,1,2,True
a1,C,12/5/2012,a,8,True,True,A1,1,2,False
a1,C,12/5/2012,a,8,True,True,B,1,2,False
...
a3,C,12/9/2012,d,8,True,True,B,1,2,False
a3,C,12/9/2012,d,8,True,True,C,1,2,False
a3,C,12/9/2012,d,8,True,True,D,1,2,True
a3,C,12/9/2012,d,8,True,True,E,1,2,False