1  r"""Command-line tool to validate and pretty-print JSON
       2  
       3  Usage::
       4  
       5      $ echo '{"json":"obj"}' | python -m json.tool
       6      {
       7          "json": "obj"
       8      }
       9      $ echo '{ 1.2:3.4}' | python -m json.tool
      10      Expecting property name enclosed in double quotes: line 1 column 3 (char 2)
      11  
      12  """
      13  import argparse
      14  import json
      15  import sys
      16  from pathlib import Path
      17  
      18  
      19  def main():
      20      prog = 'python -m json.tool'
      21      description = ('A simple command line interface for json module '
      22                     'to validate and pretty-print JSON objects.')
      23      parser = argparse.ArgumentParser(prog=prog, description=description)
      24      parser.add_argument('infile', nargs='?',
      25                          type=argparse.FileType(encoding="utf-8"),
      26                          help='a JSON file to be validated or pretty-printed',
      27                          default=sys.stdin)
      28      parser.add_argument('outfile', nargs='?',
      29                          type=Path,
      30                          help='write the output of infile to outfile',
      31                          default=None)
      32      parser.add_argument('--sort-keys', action='store_true', default=False,
      33                          help='sort the output of dictionaries alphabetically by key')
      34      parser.add_argument('--no-ensure-ascii', dest='ensure_ascii', action='store_false',
      35                          help='disable escaping of non-ASCII characters')
      36      parser.add_argument('--json-lines', action='store_true', default=False,
      37                          help='parse input using the JSON Lines format. '
      38                          'Use with --no-indent or --compact to produce valid JSON Lines output.')
      39      group = parser.add_mutually_exclusive_group()
      40      group.add_argument('--indent', default=4, type=int,
      41                         help='separate items with newlines and use this number '
      42                         'of spaces for indentation')
      43      group.add_argument('--tab', action='store_const', dest='indent',
      44                         const='\t', help='separate items with newlines and use '
      45                         'tabs for indentation')
      46      group.add_argument('--no-indent', action='store_const', dest='indent',
      47                         const=None,
      48                         help='separate items with spaces rather than newlines')
      49      group.add_argument('--compact', action='store_true',
      50                         help='suppress all whitespace separation (most compact)')
      51      options = parser.parse_args()
      52  
      53      dump_args = {
      54          'sort_keys': options.sort_keys,
      55          'indent': options.indent,
      56          'ensure_ascii': options.ensure_ascii,
      57      }
      58      if options.compact:
      59          dump_args['indent'] = None
      60          dump_args['separators'] = ',', ':'
      61  
      62      with options.infile as infile:
      63          try:
      64              if options.json_lines:
      65                  objs = (json.loads(line) for line in infile)
      66              else:
      67                  objs = (json.load(infile),)
      68  
      69              if options.outfile is None:
      70                  out = sys.stdout
      71              else:
      72                  out = options.outfile.open('w', encoding='utf-8')
      73              with out as outfile:
      74                  for obj in objs:
      75                      json.dump(obj, outfile, **dump_args)
      76                      outfile.write('\n')
      77          except ValueError as e:
      78              raise SystemExit(e)
      79  
      80  
      81  if __name__ == '__main__':
      82      try:
      83          main()
      84      except BrokenPipeError as exc:
      85          sys.exit(exc.errno)