Passing Python list in single quote

Question

I have a piece of code like below which is used to send a list of IP addresses to an API call.

body = {'cID': id, 'dbType': params['db-type'].upper(), 'cidrList': eval(params['--cidr-list'])}
print(json.dumps(body))
conn.request("POST", "/Link/to/API", body=json.dumps(body), headers=header)
check_resp(200)
logger.info("Rules changed successfully")

However, when I call this code using the below params, it fails.

--cidr-list ['10.20.0.0/32','10.30.0.0/32']

It works when I use the below.

--cidr-list [\"10.20.0.0/32\",\"10.30.0.0/32\"]

So basically when I use \" to wrap each item of the list, it is parsed as single quotes. How do I change the code so that it accepts input 1? I'm new to Python and I would appreciate if you could explain the logic behind it as well. Thanks in advance.

The user should not have to know Python in order to use your program. Don't make them provide Python literals as arguments. — chepner, Mar 17 '20 at 19:55
`--cidr-list 10.20.0.0/32,10.30.0.32`, then `body = {..., 'cidrList': params['--ciderList'].split(',')}`. — chepner, Mar 17 '20 at 19:55
Show us the API code. That's the interesting part as it's the one that doesn't seem to accept proper JSON. Also show us the headers you are sending. — kichik, Mar 17 '20 at 19:56

score 1 · Answer 1 · answered Mar 17 '20 at 19:58

You need to escape single quotes, since they're used by the shell as well.

--cidr-list [\'10.20.0.0/32\',\'10.30.0.0/32\']

The best way is to put the entire argument in quotes.

--cidr-list "['10.20.0.0/32','10.30.0.0/32']"
or
--cidr-list '["10.20.0.0/32","10.30.0.0/32"]'

BTW, you should use ast.literal_eval() rather than eval().

score 1 · Accepted Answer · answered Mar 17 '20 at 20:18

Don't make knowledge of Python a requirement to use your program.

body = {
    'cID': id,
    'dbType': params['db-type'].upper(),
    'cidrList': params['--cidr-list'].split(',')
}
print(json.dumps(body))
conn.request("POST", "/Link/to/API", json=body, headers=header)
check_resp(200)
logger.info("Rules changed successfully")

Then invoke the script with

script.py ... --cidr-list 10.20.0.0/32,10.30.0.0/32

All arguments are already strings; you don't need to force Python string-literal syntax on the user, and a comma-separated string is sufficient to process into a list of CIDR addresses without forcing Python list syntax on the user as well.

Passing Python list in single quote

2 Answers2