CODEWITHSUNDEEP
pythonregex
Sandeepan Nath
Sandeepan Nath

Reputation: 10284

Unable to parse string using python match() - getting error AttributeError: 'NoneType' object has no attribute 'group'

I have a dictionary which is output of an aerospike info command. I need to parse a value from it.

I have set it as a string to the response variable as shown below. However, it's type still shows as dictionary. So, as suggested in this answer, I have dumped it to string type and then tried to call match() (because it expects string parameter). However, I am still getting this error.

respone = "{'BB912E94CDE0B0E': (None, 'n_objects=179:n-bytes-memory=0:stop-writes-count=0:set-enable-xdr=use-default:disable-eviction=true:set-delete=false;\n')}"
p = "/.*\'n_objects=([0-9]+)\:.*/gm"
stringResponse = json.dumps(response)
print type(response)
print stringResponse
print type(stringResponse)
print re.match(p,stringResponse).group(1)

Output - 

<type 'dict'>
{"BB912E94CDE0B0E": [null, "n_objects=179:n-bytes-memory=0:stop-writes-count=0:set-enable-xdr=use-default:disable-eviction=true:set-delete=false;\n"]}
<type 'str'>
Traceback (most recent call last):
  File "Sandeepan-oauth_token_cache_complete_sanity_cp.py", line 104, in <module>
    print re.match(p,stringResponse).group(1)
AttributeError: 'NoneType' object has no attribute 'group'

I am getting the desired output using the same string and regex pattern - https://regex101.com/r/ymotqe/1

Upvotes: 1

Views: 1476

Answers (1)

Patrick Artner
Patrick Artner

Reputation: 51643

You need to correct your pattern. The /gm part at the end corresponds to flags for regex. Some other things '/' are also not needed. 

import json
import re

# fixed variable name
response = "{'BB912E94CDE0B0E': (None, 'n_objects=179:n-bytes-memory=0:stop-writes-count=0:set-enable-xdr=use-default:disable-eviction=true:set-delete=false;\n')}"

# fixed pattern
p = ".*'n_objects=([0-9]+):.*"
stringResponse = json.dumps(response)
print stringResponse
print type(response)

# fixed flags parameter (but you do not need it in your example)
print re.match(p,stringResponse, flags=re.M).group(1)

Output:

"{'BB912E94CDE0B0E': (None, 'n_objects=179:n-bytes-memory=0:stop-writes-count=0:set-enable-xdr=use-default:disable-eviction=true:set-delete=false;\n')}"
<type 'str'>
179

When using regex101.com you should also switch to python mode.

Upvotes: 2

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