Python script to convert a JSONfile with an array (or list of lines) into a CSV file

json_to_csv.py

import json, csv, sys

#USAGE: python json_to_csv.py FILENAME.json

# filename to extract is 1st arg
# output file is appended with .csv
IN = sys.argv[1]
OUT = IN + ".csv"


# use this if the json is not an array, but rather one object per row
data = []
with open(IN) as inf:
	for l in inf:
		data.append(json.loads(l))
        
# use this if the json is an array already
# with open(IN) as inf:
    # data = json.load(inf)

# get all unique fields
fields = set()
for d in data:
	fields.update(d.keys())

# print some info before saving
print(f"got {len(data)} entries from {IN}")
print(data[0].keys())

with open(OUT, "w") as outf:
	writer = csv.DictWriter(outf, fieldnames=fields)
	writer.writeheader()
	writer.writerows(data)