r"""Command-line tool to validate and pretty-print JSON
Usage::
$ echo '{"json":"obj"}' | python -m json.tool
{
"json": "obj"
}
$ echo '{ 1.2:3.4}' | python -m json.tool
Expecting property name enclosed in double quotes: line 1 column 3 (char 2)
"""
import argparse
import collections
import json
import sys
def main():
prog = 'python -m json.tool'
description = ('A simple command line interface for json module '
'to validate and pretty-print JSON objects.')
parser = argparse.ArgumentParser(prog=prog, description=description)
parser.add_argument('infile', nargs='?', type=argparse.FileType(),
help='a JSON file to be validated or pretty-printed')
parser.add_argument('outfile', nargs='?', type=argparse.FileType('w'),
help='write the output of infile to outfile')
parser.add_argument('--sort-keys', action='store_true', default=False,
help='sort the output of dictionaries alphabetically by key')
options = parser.parse_args()
infile = options.infile or sys.stdin
outfile = options.outfile or sys.stdout
sort_keys = options.sort_keys
with infile:
try:
if sort_keys:
obj = json.load(infile)
else:
obj = json.load(infile,
object_pairs_hook=collections.OrderedDict)
except ValueError as e:
raise SystemExit(e)
with outfile:
json.dump(obj, outfile, sort_keys=sort_keys, indent=4)
outfile.write('\n')
if __name__ == '__main__':
main()
