print the keys from any level of a json file

jsonkeys.py

#!/usr/bin/env python
#
# jsonkeys.py - print json keys
#

from __future__ import print_function
from sys import argv, stderr
import json


#
# usage - print usage and quite
#
def usage():
    print ("Usage: " + argv[0] + "filename:subkey_1:subkey_2:subkey_3",
           file=stderr)
    exit(1)

#
# whittle - Get a subobject by walking through keys array
#
def whittle(obj, keys):
    
    for k in keys:
        obj = obj[k]

    return obj

#
# print_keys - print json keys given a string of the following format
#     args: string formatted like "filename:subkey1:subkey2:subkey3"
#           where subkey1 is at the top level of the json object,
#           subkey2 is a child of subkey1, and subkey3 is a child of
#           subkey3
#     note: there may be zero subkeys
#     
def print_keys(cmd):
    
    parts = cmd.split(":")
    fname = parts[0]
    subkeys = parts[1:]

    try:
        obj = json.loads(open(fname).read())
    except Exception, e:
        print("Error loading JSON object from file: " + str(e), file=stderr)
        exit(1)
    obj = whittle(obj, subkeys)

    try:
        print (obj.keys())
    except:
        print (type(obj))

#
# main - parse args and call print_keys
#
def main():

    # test for input
    if len(argv) < 2:
        usage()
    
    files = argv[1:]

    # process files
    for f in files:
        print_keys(f)

main()

Sample execution

Script started on Tue Mar 14 13:11:42 2017
bash-3.2$ ./jsonkeys.py tl_2016_09_tabblock10.json 
[u'objects', u'type', u'transform', u'arcs']
bash-3.2$ ./jsonkeys.py tl_2016_09_tabblock10.json:objects
[u'r9c3', u'r5c1', u'r0c2', u'r8c9', u'r8c8', u'r8c7', u'r8c6', u'r8c5', u'r8c4', u'r8c3', u'r8c2', u'r8c1', u'r3c0', u'r2c1', u'r3c2', u'r3c3', u'r3c4', u'r3c5', u'r3c6', u'r3c7', u'r3c8', u'r3c9', u'r2c3', u'r2c2', u'r2c5', u'r2c4', u'r2c7', u'r2c6', u'r1c3', u'r5c8', u'r5c9', u'r0c1', u'r5c2', u'r5c3', u'r0c0', u'r5c6', u'r5c7', u'r5c4', u'r5c5', u'r7c4', u'r7c5', u'r7c6', u'r4c8', u'r6c9', u'r6c8', u'r7c2', u'r7c3', u'r4c3', u'r4c2', u'r6c7', u'r6c2', u'r4c7', u'r4c6', u'r6c3', u'r7c1', u'r4c4', u'r7c7', u'r1c0', u'r4c0', u'r1c1', u'r6c5', u'r6c1', u'r4c9', u'r4c1', u'r6c6', u'r2c8', u'r7c8', u'r2c0', u'r7c9', u'r3c1', u'r1c2', u'r4c5', u'r9c8', u'r9c9', u'r9c6', u'r9c7', u'r9c4', u'r9c5', u'r9c2', u'r6c4', u'r9c1']
bash-3.2$ ./jsonkeys.py tl_2016_09_tabblock10.json:type
<type 'unicode'>
bash-3.2$ ./jsonkeys.py tl_2016_09_tabblock10.json:transform
[u'translate', u'scale']
bash-3.2$ ./jsonkeys.py tl_2016_09_tabblock10.json:transform:scale
<type 'list'>
bash-3.2$ exit
exit

Script done on Tue Mar 14 13:12:49 2017