Converting a string looking list as a list in python

Question

The HTTP response header for 'packages_list' returns the following, which is a list looking string. How do i convert this to an actual list? I have tried typecasting the string as a list which didn't work. I am not keen on doing find and replace or strip. Once I have the list I am creating a windows forms with buttons with text for each of the items in list. Any help is appreciated

I am using IronPython 2.6 (yes, I know its old but cant move away for backward compatibility reasons)

['Admin', 'MMX_G10_Asia', 'MMX_G10_London', 'MMX_G10_Readonly', 'MMX_Credit_Readonly', 'MMX_Govies_ReadOnly']


httpConn = httplib.HTTPConnection(base_server_url)
httpConn.request("POST", urlparser.path, params)
response = httpConn.getresponse()
headers = dict(response.getheaders())
print headers['packages_list']

Thanks everyone for your help. to my disappointment IronPython 2.6 has a bug apparently and json.loads blows up and it does not have ast package in built. and I cant installl for backward compatibility reasons File "C:\Program Files (x86)\MMI_RADIA_PKG\IronPython 2.6\Lib\json_init_.py", line 307, in loads File "C:\Program Files (x86)\MMI_RADIA_PKG\IronPython 2.6\Lib\json\scanner.py", line 42, in iterscan AttributeError: 'NoneType' object has no attribute 'scanner' IronPython bug reference ironpython.codeplex.com/workitem/25787 — ginksman
– ginksman, Commented Jun 22, 2017 at 8:18

Mureinik · Accepted Answer · 2017-06-21 18:21:09Z

5

The simplest approach, IMHO, would be to use literal_eval:

>>> s = "['Admin', 'MMX_G10_Asia', 'MMX_G10_London', 'MMX_G10_Readonly', 'MMX_Credit_Readonly', 'MMX_Govies_ReadOnly']"
>>> s
"['Admin', 'MMX_G10_Asia', 'MMX_G10_London', 'MMX_G10_Readonly', 'MMX_Credit_Readonly', 'MMX_Govies_ReadOnly']"
>>> from ast import literal_eval
>>> literal_eval(s)
['Admin', 'MMX_G10_Asia', 'MMX_G10_London', 'MMX_G10_Readonly', 'MMX_Credit_Readonly', 'MMX_Govies_ReadOnly']

answered Jun 21, 2017 at 18:21

Mureinik

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1 Comment

ginksman Over a year ago

Thanks Mureinik for taking time to help. Sadly there is no ast in IronPython 2.6

Fred · Accepted Answer · 2017-06-21 18:28:01Z

1

You can to check if the string is a valid python type

>>> import ast
>>> s = "['Admin', 'MMX_G10_Asia', 'MMX_G10_London', 'MMX_G10_Readonly', 'MMX_Credit_Readonly', 'MMX_Govies_ReadOnly']"
>>> ast.literal_eval(s)
['Admin', 'MMX_G10_Asia', 'MMX_G10_London', 'MMX_G10_Readonly', 'MMX_Credit_Readonly', 'MMX_Govies_ReadOnly']

answered Jun 21, 2017 at 18:28

Fred

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4 Comments

ginksman Over a year ago

Thanks for the answer Fred. unfortunately the stupid IronPython 2.6 does not have ast package :-(

Fred Over a year ago

This is quite surprising !

ginksman Over a year ago

Looks like I am using the oldest of 2.6 series ' "C:\Program Files (x86)\MMI_RADIA_PKG\IronPython 2.6\ipy.exe" C:/Users//PycharmProjects/MultiPackageSupport/temp/temp1.py Traceback (most recent call last): File "C:/Users//PycharmProjects/MultiPackageSupport/temp/temp1.py", line 1, in C:/Users//PycharmProjects/MultiPackageSupport/temp/temp1.py ImportError: No module named ast Process finished with exit code 1 '

ginksman Over a year ago

Hello mate, I cant, it has been distributed to 100s of user desktops. so my work should work on their PCs with their version of IronPython. thanks

Błotosmętek · Accepted Answer · 2017-06-21 18:28:53Z

1

Another option is to convert this string to JSON format and then read it in:

import json
s = headers['packages_list'].replace("'", '"')
result = json.loads(s)

answered Jun 21, 2017 at 18:28

Błotosmętek

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4 Comments

Code-Apprentice Over a year ago

Do you really need to replace all '' with "? Doesn't JSON use either one to enclose a string literal?

Błotosmętek Over a year ago

@Code-Apprentice not sure what JSON specification says, but json.load only accepts " as string delimiter.

Code-Apprentice Over a year ago

The example at docs.python.org/2/library/json.html and docs.python.org/3/library/json.html says otherwise: >>> json.loads('["foo", {"bar":["baz", null, 1.0, 2]}]').

Code-Apprentice Over a year ago

Oh wait...I had it backwards. My bad.

ginksman · Accepted Answer · 2017-06-22 09:50:20Z

0

Ugly but I am going with the below. Thanks again everyone for the help !

headers = dict(response.getheaders())
print headers['packages_list']
result = headers['packages_list'].replace("'",'')
result = result.replace("[","")
result = result.replace("]", "")
print result
package_list = result.split(",") 
print "the 2nd item in teh list is ", package_list[1]

answered Jun 22, 2017 at 9:50

ginksman

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