Adding variable inside quotes in a python script

Question

I'm writing a python script to automate some bash commands and am having trouble with passing a variable inside the curl command. This is what I have:

subprocess.call('''curl -H 'Content-Type: application/json' -X PUT -d '{"name": "{}".format(someVariable), "hive_ql": "CREATE VIEW user_balance AS SELECT NAME, LOB,ACCOUNT,BALANCE FROM csvtable"}' localhost:someport/api''', shell=True)

I'm trying to pass a variable in for the 'name' parameter, denoted by 'someVariable' in this example. But I get an error stating:

"message": "Failed to decode JSON object: Expecting ',' delimiter: line 1 column 14 (char 13):

When I replace the format part with an actual string, the script executes just fine so I know I'm doing something wrong with passing the variable between the quotes, just not sure what the correct syntax is.

call takes a list of strings. See the docs: docs.python.org/3/library/subprocess.html#subprocess.run — Patrick Haugh
– Patrick Haugh, Commented Nov 17, 2016 at 19:07

chepner · Accepted Answer · 2016-11-17 21:48:44Z

2

It will be clearer to pass a list to subprocess.call:

import json
import subprocess

someVariable = 'hello'
hive_ql = 'CREATE VIEW user_balance AS SELECT NAME, LOB,ACCOUNT,BALANCE FROM csvtable'  # noqa

subprocess.call([
    'curl',
    '-H',
    'Content-Type: application/json',
    '-X',
    'PUT',
    '-d',
    json.dumps({
      'name': str(someVariable),
      'hive_ql': hive_ql
    }),
    'localhost:someport/api'
])

edited Nov 17, 2016 at 21:48

chepner

538k77 gold badges594 silver badges746 bronze badges

answered Nov 17, 2016 at 19:11

JuniorCompressor

20.1k4 gold badges33 silver badges58 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

covfefe Over a year ago

When I run this, I get 'curl: try 'curl --help' or 'curl --manual' for more information'

JuniorCompressor Over a year ago

Try removing shell=True

covfefe Over a year ago

^That worked, thanks! Any idea why that might have been the issue?

covfefe Over a year ago

Looks like shell=True is only needed if subprocess is calling a single line (as opposed to an array as in this example)

Christopher Shroba · Accepted Answer · 2016-11-17 21:55:31Z

1

You aren't calling .format, it's inside your string. Try this:

subprocess.call('''curl -H 'Content-Type: application/json' -X PUT -d '{"name": "{}", "hive_ql": "CREATE VIEW user_balance AS SELECT NAME, LOB,ACCOUNT,BALANCE FROM csvtable"}' localhost:someport/api'''.format(someVariable), shell=True)

As it stands, the JSON you're trying to decode is:

{
  "name": "{}".format(someVariable),
  "hive_ql": "CREATE VIEW user_balance AS SELECT NAME, LOB,ACCOUNT,BALANCE FROM csvtable"
}

because python is just treating .format(someVariable) as part of the string and not replacing it with the value of someVariable, and clearly it is not valid JSON to have that hanging onto the end of a string.

Edit: I forgot to escape the brackets; try this instead:

subprocess.call('''curl -H 'Content-Type: application/json' -X PUT -d '{{"name": "{}", "hive_ql": "CREATE VIEW user_balance AS SELECT NAME, LOB,ACCOUNT,BALANCE FROM csvtable"}}' localhost:someport/api'''.format(someVariable), shell=True)

edited Nov 17, 2016 at 21:55

answered Nov 17, 2016 at 19:08

Christopher Shroba

7,6948 gold badges48 silver badges75 bronze badges

1 Comment

covfefe Over a year ago

When I ran this, I got KeyError: '"name"'

Collectives™ on Stack Overflow

Adding variable inside quotes in a python script

2 Answers 2

4 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related