From: Serhiy Storchaka Date: Sat, 8 Nov 2025 10:07:27 +0000 (+0200) Subject: gh-140793: Improve documentatation and tests for the ensure_ascii option in the json... X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=7e90bac3cc6fd68fe6696ab4bce1262751de7531;p=thirdparty%2FPython%2Fcpython.git gh-140793: Improve documentatation and tests for the ensure_ascii option in the json module (GH-140906) * Document that ensure_ascii=True forces escaping not only non-ASCII, but also non-printable characters (the only affected ASCII character is U+007F). * Ensure that the help output for the json module does not exceed 80 columns (except one long line in an example and generated lines). * Add more tests. --- diff --git a/Doc/library/json.rst b/Doc/library/json.rst index 12a5a96a3c56..8b4217c210d5 100644 --- a/Doc/library/json.rst +++ b/Doc/library/json.rst @@ -183,8 +183,10 @@ Basic Usage :param bool ensure_ascii: If ``True`` (the default), the output is guaranteed to - have all incoming non-ASCII characters escaped. - If ``False``, these characters will be outputted as-is. + have all incoming non-ASCII and non-printable characters escaped. + If ``False``, all characters will be outputted as-is, except for + the characters that must be escaped: quotation mark, reverse solidus, + and the control characters U+0000 through U+001F. :param bool check_circular: If ``False``, the circular reference check for container types is skipped @@ -495,8 +497,10 @@ Encoders and Decoders :class:`bool` or ``None``. If *skipkeys* is true, such items are simply skipped. If *ensure_ascii* is true (the default), the output is guaranteed to - have all incoming non-ASCII characters escaped. If *ensure_ascii* is - false, these characters will be output as-is. + have all incoming non-ASCII and non-printable characters escaped. + If *ensure_ascii* is false, all characters will be output as-is, except for + the characters that must be escaped: quotation mark, reverse solidus, + and the control characters U+0000 through U+001F. If *check_circular* is true (the default), then lists, dicts, and custom encoded objects will be checked for circular references during encoding to @@ -636,7 +640,7 @@ UTF-32, with UTF-8 being the recommended default for maximum interoperability. As permitted, though not required, by the RFC, this module's serializer sets *ensure_ascii=True* by default, thus escaping the output so that the resulting -strings only contain ASCII characters. +strings only contain printable ASCII characters. Other than the *ensure_ascii* parameter, this module is defined strictly in terms of conversion between Python objects and diff --git a/Lib/json/__init__.py b/Lib/json/__init__.py index c8fdd0d99a0e..89396b25a2cb 100644 --- a/Lib/json/__init__.py +++ b/Lib/json/__init__.py @@ -127,8 +127,9 @@ def dump(obj, fp, *, skipkeys=False, ensure_ascii=True, check_circular=True, instead of raising a ``TypeError``. If ``ensure_ascii`` is false, then the strings written to ``fp`` can - contain non-ASCII characters if they appear in strings contained in - ``obj``. Otherwise, all such characters are escaped in JSON strings. + contain non-ASCII and non-printable characters if they appear in strings + contained in ``obj``. Otherwise, all such characters are escaped in JSON + strings. If ``check_circular`` is false, then the circular reference check for container types will be skipped and a circular reference will @@ -144,10 +145,11 @@ def dump(obj, fp, *, skipkeys=False, ensure_ascii=True, check_circular=True, level of 0 will only insert newlines. ``None`` is the most compact representation. - If specified, ``separators`` should be an ``(item_separator, key_separator)`` - tuple. The default is ``(', ', ': ')`` if *indent* is ``None`` and - ``(',', ': ')`` otherwise. To get the most compact JSON representation, - you should specify ``(',', ':')`` to eliminate whitespace. + If specified, ``separators`` should be an ``(item_separator, + key_separator)`` tuple. The default is ``(', ', ': ')`` if *indent* is + ``None`` and ``(',', ': ')`` otherwise. To get the most compact JSON + representation, you should specify ``(',', ':')`` to eliminate + whitespace. ``default(obj)`` is a function that should return a serializable version of obj or raise TypeError. The default simply raises TypeError. @@ -188,9 +190,10 @@ def dumps(obj, *, skipkeys=False, ensure_ascii=True, check_circular=True, (``str``, ``int``, ``float``, ``bool``, ``None``) will be skipped instead of raising a ``TypeError``. - If ``ensure_ascii`` is false, then the return value can contain non-ASCII - characters if they appear in strings contained in ``obj``. Otherwise, all - such characters are escaped in JSON strings. + If ``ensure_ascii`` is false, then the return value can contain + non-ASCII and non-printable characters if they appear in strings + contained in ``obj``. Otherwise, all such characters are escaped in + JSON strings. If ``check_circular`` is false, then the circular reference check for container types will be skipped and a circular reference will @@ -206,10 +209,11 @@ def dumps(obj, *, skipkeys=False, ensure_ascii=True, check_circular=True, level of 0 will only insert newlines. ``None`` is the most compact representation. - If specified, ``separators`` should be an ``(item_separator, key_separator)`` - tuple. The default is ``(', ', ': ')`` if *indent* is ``None`` and - ``(',', ': ')`` otherwise. To get the most compact JSON representation, - you should specify ``(',', ':')`` to eliminate whitespace. + If specified, ``separators`` should be an ``(item_separator, + key_separator)`` tuple. The default is ``(', ', ': ')`` if *indent* is + ``None`` and ``(',', ': ')`` otherwise. To get the most compact JSON + representation, you should specify ``(',', ':')`` to eliminate + whitespace. ``default(obj)`` is a function that should return a serializable version of obj or raise TypeError. The default simply raises TypeError. @@ -280,11 +284,12 @@ def load(fp, *, cls=None, object_hook=None, parse_float=None, ``object_hook`` will be used instead of the ``dict``. This feature can be used to implement custom decoders (e.g. JSON-RPC class hinting). - ``object_pairs_hook`` is an optional function that will be called with the - result of any object literal decoded with an ordered list of pairs. The - return value of ``object_pairs_hook`` will be used instead of the ``dict``. - This feature can be used to implement custom decoders. If ``object_hook`` - is also defined, the ``object_pairs_hook`` takes priority. + ``object_pairs_hook`` is an optional function that will be called with + the result of any object literal decoded with an ordered list of pairs. + The return value of ``object_pairs_hook`` will be used instead of the + ``dict``. This feature can be used to implement custom decoders. If + ``object_hook`` is also defined, the ``object_pairs_hook`` takes + priority. To use a custom ``JSONDecoder`` subclass, specify it with the ``cls`` kwarg; otherwise ``JSONDecoder`` is used. @@ -305,11 +310,12 @@ def loads(s, *, cls=None, object_hook=None, parse_float=None, ``object_hook`` will be used instead of the ``dict``. This feature can be used to implement custom decoders (e.g. JSON-RPC class hinting). - ``object_pairs_hook`` is an optional function that will be called with the - result of any object literal decoded with an ordered list of pairs. The - return value of ``object_pairs_hook`` will be used instead of the ``dict``. - This feature can be used to implement custom decoders. If ``object_hook`` - is also defined, the ``object_pairs_hook`` takes priority. + ``object_pairs_hook`` is an optional function that will be called with + the result of any object literal decoded with an ordered list of pairs. + The return value of ``object_pairs_hook`` will be used instead of the + ``dict``. This feature can be used to implement custom decoders. If + ``object_hook`` is also defined, the ``object_pairs_hook`` takes + priority. ``parse_float``, if specified, will be called with the string of every JSON float to be decoded. By default this is equivalent to diff --git a/Lib/json/decoder.py b/Lib/json/decoder.py index ff4bfcdcc407..92ad63525576 100644 --- a/Lib/json/decoder.py +++ b/Lib/json/decoder.py @@ -297,10 +297,10 @@ class JSONDecoder(object): place of the given ``dict``. This can be used to provide custom deserializations (e.g. to support JSON-RPC class hinting). - ``object_pairs_hook``, if specified will be called with the result of - every JSON object decoded with an ordered list of pairs. The return - value of ``object_pairs_hook`` will be used instead of the ``dict``. - This feature can be used to implement custom decoders. + ``object_pairs_hook``, if specified will be called with the result + of every JSON object decoded with an ordered list of pairs. The + return value of ``object_pairs_hook`` will be used instead of the + ``dict``. This feature can be used to implement custom decoders. If ``object_hook`` is also defined, the ``object_pairs_hook`` takes priority. diff --git a/Lib/json/encoder.py b/Lib/json/encoder.py index bc446e0f377a..5cf6d64f3ead 100644 --- a/Lib/json/encoder.py +++ b/Lib/json/encoder.py @@ -111,9 +111,10 @@ class JSONEncoder(object): encoding of keys that are not str, int, float, bool or None. If skipkeys is True, such items are simply skipped. - If ensure_ascii is true, the output is guaranteed to be str - objects with all incoming non-ASCII characters escaped. If - ensure_ascii is false, the output can contain non-ASCII characters. + If ensure_ascii is true, the output is guaranteed to be str objects + with all incoming non-ASCII and non-printable characters escaped. + If ensure_ascii is false, the output can contain non-ASCII and + non-printable characters. If check_circular is true, then lists, dicts, and custom encoded objects will be checked for circular references during encoding to @@ -134,14 +135,15 @@ class JSONEncoder(object): indent level. An indent level of 0 will only insert newlines. None is the most compact representation. - If specified, separators should be an (item_separator, key_separator) - tuple. The default is (', ', ': ') if *indent* is ``None`` and - (',', ': ') otherwise. To get the most compact JSON representation, - you should specify (',', ':') to eliminate whitespace. + If specified, separators should be an (item_separator, + key_separator) tuple. The default is (', ', ': ') if *indent* is + ``None`` and (',', ': ') otherwise. To get the most compact JSON + representation, you should specify (',', ':') to eliminate + whitespace. If specified, default is a function that gets called for objects - that can't otherwise be serialized. It should return a JSON encodable - version of the object or raise a ``TypeError``. + that can't otherwise be serialized. It should return a JSON + encodable version of the object or raise a ``TypeError``. """ diff --git a/Lib/test/test_json/test_encode_basestring_ascii.py b/Lib/test/test_json/test_encode_basestring_ascii.py index 6a39b72a09df..c90d3e968e5e 100644 --- a/Lib/test/test_json/test_encode_basestring_ascii.py +++ b/Lib/test/test_json/test_encode_basestring_ascii.py @@ -8,13 +8,12 @@ CASES = [ ('\u0123\u4567\u89ab\ucdef\uabcd\uef4a', '"\\u0123\\u4567\\u89ab\\ucdef\\uabcd\\uef4a"'), ('controls', '"controls"'), ('\x08\x0c\n\r\t', '"\\b\\f\\n\\r\\t"'), + ('\x00\x1f\x7f', '"\\u0000\\u001f\\u007f"'), ('{"object with 1 member":["array with 1 element"]}', '"{\\"object with 1 member\\":[\\"array with 1 element\\"]}"'), (' s p a c e d ', '" s p a c e d "'), ('\U0001d120', '"\\ud834\\udd20"'), ('\u03b1\u03a9', '"\\u03b1\\u03a9"'), ("`1~!@#$%^&*()_+-={':[,]}|;.?", '"`1~!@#$%^&*()_+-={\':[,]}|;.?"'), - ('\x08\x0c\n\r\t', '"\\b\\f\\n\\r\\t"'), - ('\u0123\u4567\u89ab\ucdef\uabcd\uef4a', '"\\u0123\\u4567\\u89ab\\ucdef\\uabcd\\uef4a"'), ] class TestEncodeBasestringAscii: diff --git a/Lib/test/test_json/test_unicode.py b/Lib/test/test_json/test_unicode.py index 68629cceeb9b..1aa9546dc463 100644 --- a/Lib/test/test_json/test_unicode.py +++ b/Lib/test/test_json/test_unicode.py @@ -32,6 +32,29 @@ class TestUnicode: j = self.dumps(u + "\n", ensure_ascii=False) self.assertEqual(j, f'"{u}\\n"') + def test_ascii_non_printable_encode(self): + u = '\b\t\n\f\r\x00\x1f\x7f' + self.assertEqual(self.dumps(u), + '"\\b\\t\\n\\f\\r\\u0000\\u001f\\u007f"') + self.assertEqual(self.dumps(u, ensure_ascii=False), + '"\\b\\t\\n\\f\\r\\u0000\\u001f\x7f"') + + def test_ascii_non_printable_decode(self): + self.assertEqual(self.loads('"\\b\\t\\n\\f\\r"'), + '\b\t\n\f\r') + s = ''.join(map(chr, range(32))) + for c in s: + self.assertRaises(self.JSONDecodeError, self.loads, f'"{c}"') + self.assertEqual(self.loads(f'"{s}"', strict=False), s) + self.assertEqual(self.loads('"\x7f"'), '\x7f') + + def test_escaped_decode(self): + self.assertEqual(self.loads('"\\b\\t\\n\\f\\r"'), '\b\t\n\f\r') + self.assertEqual(self.loads('"\\"\\\\\\/"'), '"\\/') + for c in set(map(chr, range(0x100))) - set('"\\/bfnrt'): + self.assertRaises(self.JSONDecodeError, self.loads, f'"\\{c}"') + self.assertRaises(self.JSONDecodeError, self.loads, f'"\\{c}"', strict=False) + def test_big_unicode_encode(self): u = '\U0001d120' self.assertEqual(self.dumps(u), '"\\ud834\\udd20"') @@ -48,6 +71,18 @@ class TestUnicode: s = f'"\\u{i:04x}"' self.assertEqual(self.loads(s), u) + def test_single_surrogate_encode(self): + self.assertEqual(self.dumps('\uD83D'), '"\\ud83d"') + self.assertEqual(self.dumps('\uD83D', ensure_ascii=False), '"\ud83d"') + self.assertEqual(self.dumps('\uDC0D'), '"\\udc0d"') + self.assertEqual(self.dumps('\uDC0D', ensure_ascii=False), '"\udc0d"') + + def test_single_surrogate_decode(self): + self.assertEqual(self.loads('"\uD83D"'), '\ud83d') + self.assertEqual(self.loads('"\\uD83D"'), '\ud83d') + self.assertEqual(self.loads('"\udc0d"'), '\udc0d') + self.assertEqual(self.loads('"\\udc0d"'), '\udc0d') + def test_unicode_preservation(self): self.assertEqual(type(self.loads('""')), str) self.assertEqual(type(self.loads('"a"')), str)