diff --git a/Doc/library/json.rst b/Doc/library/json.rst
--- a/Doc/library/json.rst
+++ b/Doc/library/json.rst
@@ -99,16 +99,18 @@ Using json.tool from the shell to valida
$ echo '{"json":"obj"}' | python -mjson.tool
{
"json": "obj"
}
$ echo '{1.2:3.4}' | python -mjson.tool
Expecting property name enclosed in double quotes: line 1 column 2 (char 1)
+See :ref:`json-commandline` for detailed documentation.
+
.. highlight:: python3
.. note::
JSON is a subset of `YAML `_ 1.2. The JSON produced by
this module's default settings (in particular, the default *separators*
value) is also a subset of YAML 1.0 and 1.1. This module can thus also be
used as a YAML serializer.
@@ -558,8 +560,57 @@ does not specify how repeated names in J
default, this module does not raise an exception; instead, it ignores all but
the last name-value pair for a given name::
>>> weird_json = '{"x": 1, "x": 2, "x": 3}'
>>> json.loads(weird_json)
{'x': 3}
The *object_pairs_hook* parameter can be used to alter this behavior.
+
+.. highlight:: bash
+
+.. _json-commandline:
+
+Command Line Interface
+----------------------
+
+The :mod:`json` module provides a simple command line interface to validate
+and pretty-print JSON objects.
+
+If the optional :option:`infile` and :option:`outfile` arguments are not specified,
+:attr:`sys.stdin` and :attr:`sys.stdout` will be used respectively::
+
+ $ 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 2 (char 1)
+
+
+Command line options
+^^^^^^^^^^^^^^^^^^^^
+
+.. cmdoption:: []
+
+ The JSON file to be validated or pretty-printed::
+
+ $ python -m json.tool mp_films.json
+ [
+ {
+ "title": "And Now for Something Completely Different",
+ "year": 1971
+ },
+ {
+ "title": "Monty Python and the Holy Grail",
+ "year": 1975
+ }
+ ]
+
+.. cmdoption:: []
+
+ Write the output of the *infile* to the given *outfile*. Otherwise, write it
+ to :attr:`sys.stdout`.
+
+.. cmdoption:: -h, --help
+
+ Show the help message.
diff --git a/Lib/json/tool.py b/Lib/json/tool.py
--- a/Lib/json/tool.py
+++ b/Lib/json/tool.py
@@ -5,35 +5,39 @@ 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 json
import sys
-import json
+
def main():
- if len(sys.argv) == 1:
- infile = sys.stdin
- outfile = sys.stdout
- elif len(sys.argv) == 2:
- infile = open(sys.argv[1], 'r')
- outfile = sys.stdout
- elif len(sys.argv) == 3:
- infile = open(sys.argv[1], 'r')
- outfile = open(sys.argv[2], 'w')
- else:
- raise SystemExit(sys.argv[0] + " [infile [outfile]]")
+ 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')
+ options = parser.parse_args()
+
+ infile = options.infile or sys.stdin
+ outfile = options.outfile or sys.stdout
with infile:
try:
obj = json.load(infile)
except ValueError as e:
raise SystemExit(e)
with outfile:
json.dump(obj, outfile, sort_keys=True, indent=4)
outfile.write('\n')
+ sys.exit(0)
if __name__ == '__main__':
main()
diff --git a/Lib/test/test_json/test_tool.py b/Lib/test/test_json/test_tool.py
--- a/Lib/test/test_json/test_tool.py
+++ b/Lib/test/test_json/test_tool.py
@@ -50,20 +50,28 @@ class TestTool(unittest.TestCase):
with open(infile, "w") as fp:
self.addCleanup(os.remove, infile)
fp.write(self.data)
return infile
def test_infile_stdout(self):
infile = self._create_infile()
rc, out, err = assert_python_ok('-m', 'json.tool', infile)
+ self.assertEqual(rc, 0)
self.assertEqual(out.splitlines(), self.expect.encode().splitlines())
self.assertEqual(err, b'')
def test_infile_outfile(self):
infile = self._create_infile()
outfile = support.TESTFN + '.out'
rc, out, err = assert_python_ok('-m', 'json.tool', infile, outfile)
self.addCleanup(os.remove, outfile)
with open(outfile, "r") as fp:
self.assertEqual(fp.read(), self.expect)
+ self.assertEqual(rc, 0)
self.assertEqual(out, b'')
self.assertEqual(err, b'')
+
+ def test_help_flag(self):
+ rc, out, err = assert_python_ok('-m', 'json.tool', '-h')
+ self.assertEqual(rc, 0)
+ self.assertTrue(out.startswith(b'usage: '))
+ self.assertEqual(err, b'')