[Python-checkins] cpython: improve the command-line interface of json.tool (closes #21000)

Sat Mar 22 05:17:59 CET 2014

http://hg.python.org/cpython/rev/a2ad16e86e60
changeset: 89914:a2ad16e86e60
user: Benjamin Peterson <benjamin at python.org>
date: Fri Mar 21 23:17:29 2014 -0500
summary:
 improve the command-line interface of json.tool (closes #21000)
A patch from Berker Peksag.
files:
 Doc/library/json.rst | 51 +++++++++++++++++++++
 Lib/json/tool.py | 27 ++++++----
 Lib/test/test_json/test_tool.py | 8 +++
 Misc/NEWS | 2 +
 4 files changed, 76 insertions(+), 12 deletions(-)

diff --git a/Doc/library/json.rst b/Doc/library/json.rst
--- a/Doc/library/json.rst
+++ b/Doc/library/json.rst
@@ -104,6 +104,8 @@
 $ 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::
@@ -563,3 +565,52 @@
 {'x': 3}
 
 The *object_pairs_hook* parameter can be used to alter this behavior.
+
+.. highlight:: bash
+
+.. _json-commandline:
+
+Command Line Interface
+----------------------
+
+The :mod:`json.tool` 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:: [<infile>]
+
+ 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:: [<outfile>]
+
+ 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
@@ -10,21 +10,24 @@
 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)
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
@@ -55,6 +55,7 @@
 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'')
 
@@ -65,5 +66,12 @@
 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'')
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -23,6 +23,8 @@
 Library
 -------
 
+- Issue #21000: Improve the command-line interface of json.tool.
+
 - Issue #20995: Enhance default ciphers used by the ssl module to enable
 better security an prioritize perfect forward secrecy.
 
-- 
Repository URL: http://hg.python.org/cpython
