Parse empty tag with ElementTree
Clash Royale CLAN TAG#URR8PPPParse empty tag with ElementTree
Trying to parse XML using ElementTree. I cannot figure out how to treat empty tags like <tag/>. If the tag is not present at all, .find() returns None and everything is fine. However with <tag>, .find() returns something and the consequent attempt to call text fails with error:
<tag/>
.find()
None
<tag>
.find()
text
TypeError: must be str, not NoneType
Failing example below. It will fail to parse the line <tl><mpa/></tl>
<tl><mpa/></tl>
from xml.etree import ElementTree
def getStuff(xml_message):
message_tree = ElementTree.fromstring(xml_message)
ns = {'a': 'http://www.example.org/a',
'b': 'http://www.example.org/b'}
tls = message_tree.findall('.//b:tl', namespaces = ns)
result, i = (0,)*2
for tl in tls:
i += 1
print("Item: " + str(i))
mpa = tl.find("b:mpa", namespaces = ns)
if mpa is None:
result = result + 0
print(" |--> Is None, assigned 0.")
else:
print(" |--> Is Something")
# This is where things go terribly wrong
print(" |--> Tag Value: " + mpa.text)
result = result + int(mpa.text)
return result
instr = """<?xml version="1.0" standalone='no'?>
<ncr xmlns="http://www.example.org/a">
<x xmlns="http://www.example.org/b">
<tl><ec code="N">e1</ec></tl>
<tl><mpa>0010</mpa></tl>
<tl><mpa/></tl>
</x>
</ncr>
"""
getStuff(instr)
1 Answer
1
With an empty tag <mpa/>, your mpa variable is a valid node so it is not None, but mpa.text is None because there's no text inside. Your attempt to concatenate a string " |--> Tag Value: " to None therefore fails since concatenation only works on two strings. Instead, you can use the formatting operator to format None as 'None', and add a condition to the following line to avoid converting mpa.text to an integer if it is None:
<mpa/>
mpa
None
mpa.text
None
" |--> Tag Value: "
None
None
'None'
mpa.text
None
print(" |--> Tag Value: %s" % mpa.text)
if mpa.text is not None:
result = result + int(mpa.text)
With the above change the output becomes:
Item: 1
|--> Is None, assigned 0.
Item: 2
|--> Is Something
|--> Tag Value: 0010
Item: 3
|--> Is Something
|--> Tag Value: None
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