| r"""A simple, fast, extensible JSON encoder and decoder |
| |
| JSON (JavaScript Object Notation) <http://json.org> is a subset of |
| JavaScript syntax (ECMA-262 3rd edition) used as a lightweight data |
| interchange format. |
| |
| json exposes an API familiar to uses of the standard library |
| marshal and pickle modules. |
| |
| Encoding basic Python object hierarchies:: |
| |
| >>> import json |
| >>> json.dumps(['foo', {'bar': ('baz', None, 1.0, 2)}]) |
| '["foo", {"bar": ["baz", null, 1.0, 2]}]' |
| >>> print(json.dumps("\"foo\bar")) |
| "\"foo\bar" |
| >>> print(json.dumps('\u1234')) |
| "\u1234" |
| >>> print(json.dumps('\\')) |
| "\\" |
| >>> print(json.dumps({"c": 0, "b": 0, "a": 0}, sort_keys=True)) |
| {"a": 0, "b": 0, "c": 0} |
| >>> from io import StringIO |
| >>> io = StringIO() |
| >>> json.dump(['streaming API'], io) |
| >>> io.getvalue() |
| '["streaming API"]' |
| |
| Compact encoding:: |
| |
| >>> import json |
| >>> json.dumps([1,2,3,{'4': 5, '6': 7}], separators=(',',':')) |
| '[1,2,3,{"4":5,"6":7}]' |
| |
| Pretty printing (using repr() because of extraneous whitespace in the output):: |
| |
| >>> import json |
| >>> print(repr(json.dumps({'4': 5, '6': 7}, sort_keys=True, indent=4))) |
| '{\n "4": 5, \n "6": 7\n}' |
| |
| Decoding JSON:: |
| |
| >>> import json |
| >>> json.loads('["foo", {"bar":["baz", null, 1.0, 2]}]') |
| ['foo', {'bar': ['baz', None, 1.0, 2]}] |
| >>> json.loads('"\\"foo\\bar"') |
| '"foo\x08ar' |
| >>> from io import StringIO |
| >>> io = StringIO('["streaming API"]') |
| >>> json.load(io) |
| ['streaming API'] |
| |
| Specializing JSON object decoding:: |
| |
| >>> import json |
| >>> def as_complex(dct): |
| ... if '__complex__' in dct: |
| ... return complex(dct['real'], dct['imag']) |
| ... return dct |
| ... |
| >>> json.loads('{"__complex__": true, "real": 1, "imag": 2}', |
| ... object_hook=as_complex) |
| (1+2j) |
| >>> import decimal |
| >>> json.loads('1.1', parse_float=decimal.Decimal) |
| Decimal('1.1') |
| |
| Extending JSONEncoder:: |
| |
| >>> import json |
| >>> class ComplexEncoder(json.JSONEncoder): |
| ... def default(self, obj): |
| ... if isinstance(obj, complex): |
| ... return [obj.real, obj.imag] |
| ... return json.JSONEncoder.default(self, obj) |
| ... |
| >>> dumps(2 + 1j, cls=ComplexEncoder) |
| '[2.0, 1.0]' |
| >>> ComplexEncoder().encode(2 + 1j) |
| '[2.0, 1.0]' |
| >>> list(ComplexEncoder().iterencode(2 + 1j)) |
| ['[', '2.0', ', ', '1.0', ']'] |
| |
| |
| Using json.tool from the shell to validate and |
| pretty-print:: |
| |
| $ echo '{"json":"obj"}' | python -mjson.tool |
| { |
| "json": "obj" |
| } |
| $ echo '{ 1.2:3.4}' | python -mjson.tool |
| Expecting property name: line 1 column 2 (char 2) |
| |
| Note that the JSON produced by this module's default settings |
| is a subset of YAML, so it may be used as a serializer for that as well. |
| |
| """ |
| |
| __version__ = '1.9' |
| __all__ = [ |
| 'dump', 'dumps', 'load', 'loads', |
| 'JSONDecoder', 'JSONEncoder', |
| ] |
| |
| __author__ = 'Bob Ippolito <bob@redivi.com>' |
| |
| from .decoder import JSONDecoder |
| from .encoder import JSONEncoder |
| |
| _default_encoder = JSONEncoder( |
| skipkeys=False, |
| ensure_ascii=True, |
| check_circular=True, |
| allow_nan=True, |
| indent=None, |
| separators=None, |
| encoding='utf-8', |
| default=None, |
| ) |
| |
| def dump(obj, fp, skipkeys=False, ensure_ascii=True, check_circular=True, |
| allow_nan=True, cls=None, indent=None, separators=None, |
| encoding='utf-8', default=None, **kw): |
| """Serialize ``obj`` as a JSON formatted stream to ``fp`` (a |
| ``.write()``-supporting file-like object). |
| |
| If ``skipkeys`` is ``True`` then ``dict`` keys that are not basic types |
| (``str``, ``unicode``, ``int``, ``long``, ``float``, ``bool``, ``None``) |
| will be skipped instead of raising a ``TypeError``. |
| |
| If ``ensure_ascii`` is ``False``, then the some chunks written to ``fp`` |
| may be ``unicode`` instances, subject to normal Python ``str`` to |
| ``unicode`` coercion rules. Unless ``fp.write()`` explicitly |
| understands ``unicode`` (as in ``codecs.getwriter()``) this is likely |
| to cause an error. |
| |
| If ``check_circular`` is ``False``, then the circular reference check |
| for container types will be skipped and a circular reference will |
| result in an ``OverflowError`` (or worse). |
| |
| If ``allow_nan`` is ``False``, then it will be a ``ValueError`` to |
| serialize out of range ``float`` values (``nan``, ``inf``, ``-inf``) |
| in strict compliance of the JSON specification, instead of using the |
| JavaScript equivalents (``NaN``, ``Infinity``, ``-Infinity``). |
| |
| If ``indent`` is a non-negative integer, then JSON array elements and object |
| members will be pretty-printed with that indent level. An indent level |
| of 0 will only insert newlines. ``None`` is the most compact representation. |
| |
| If ``separators`` is an ``(item_separator, dict_separator)`` tuple |
| then it will be used instead of the default ``(', ', ': ')`` separators. |
| ``(',', ':')`` is the most compact JSON representation. |
| |
| ``encoding`` is the character encoding for str instances, default is UTF-8. |
| |
| ``default(obj)`` is a function that should return a serializable version |
| of obj or raise TypeError. The default simply raises TypeError. |
| |
| To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the |
| ``.default()`` method to serialize additional types), specify it with |
| the ``cls`` kwarg. |
| |
| """ |
| # cached encoder |
| if (skipkeys is False and ensure_ascii is True and |
| check_circular is True and allow_nan is True and |
| cls is None and indent is None and separators is None and |
| encoding == 'utf-8' and default is None and not kw): |
| iterable = _default_encoder.iterencode(obj) |
| else: |
| if cls is None: |
| cls = JSONEncoder |
| iterable = cls(skipkeys=skipkeys, ensure_ascii=ensure_ascii, |
| check_circular=check_circular, allow_nan=allow_nan, indent=indent, |
| separators=separators, encoding=encoding, |
| default=default, **kw).iterencode(obj) |
| # could accelerate with writelines in some versions of Python, at |
| # a debuggability cost |
| for chunk in iterable: |
| fp.write(chunk) |
| |
| |
| def dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True, |
| allow_nan=True, cls=None, indent=None, separators=None, |
| encoding='utf-8', default=None, **kw): |
| """Serialize ``obj`` to a JSON formatted ``str``. |
| |
| If ``skipkeys`` is ``True`` then ``dict`` keys that are not basic types |
| (``str``, ``unicode``, ``int``, ``long``, ``float``, ``bool``, ``None``) |
| will be skipped instead of raising a ``TypeError``. |
| |
| If ``ensure_ascii`` is ``False``, then the return value will be a |
| ``unicode`` instance subject to normal Python ``str`` to ``unicode`` |
| coercion rules instead of being escaped to an ASCII ``str``. |
| |
| If ``check_circular`` is ``False``, then the circular reference check |
| for container types will be skipped and a circular reference will |
| result in an ``OverflowError`` (or worse). |
| |
| If ``allow_nan`` is ``False``, then it will be a ``ValueError`` to |
| serialize out of range ``float`` values (``nan``, ``inf``, ``-inf``) in |
| strict compliance of the JSON specification, instead of using the |
| JavaScript equivalents (``NaN``, ``Infinity``, ``-Infinity``). |
| |
| If ``indent`` is a non-negative integer, then JSON array elements and |
| object members will be pretty-printed with that indent level. An indent |
| level of 0 will only insert newlines. ``None`` is the most compact |
| representation. |
| |
| If ``separators`` is an ``(item_separator, dict_separator)`` tuple |
| then it will be used instead of the default ``(', ', ': ')`` separators. |
| ``(',', ':')`` is the most compact JSON representation. |
| |
| ``encoding`` is the character encoding for str instances, default is UTF-8. |
| |
| ``default(obj)`` is a function that should return a serializable version |
| of obj or raise TypeError. The default simply raises TypeError. |
| |
| To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the |
| ``.default()`` method to serialize additional types), specify it with |
| the ``cls`` kwarg. |
| |
| """ |
| # cached encoder |
| if (skipkeys is False and ensure_ascii is True and |
| check_circular is True and allow_nan is True and |
| cls is None and indent is None and separators is None and |
| encoding == 'utf-8' and default is None and not kw): |
| return _default_encoder.encode(obj) |
| if cls is None: |
| cls = JSONEncoder |
| return cls( |
| skipkeys=skipkeys, ensure_ascii=ensure_ascii, |
| check_circular=check_circular, allow_nan=allow_nan, indent=indent, |
| separators=separators, encoding=encoding, default=default, |
| **kw).encode(obj) |
| |
| |
| _default_decoder = JSONDecoder(encoding=None, object_hook=None) |
| |
| |
| def load(fp, encoding=None, cls=None, object_hook=None, parse_float=None, |
| parse_int=None, parse_constant=None, **kw): |
| """Deserialize ``fp`` (a ``.read()``-supporting file-like object |
| containing a JSON document) to a Python object. |
| |
| If the contents of ``fp`` is encoded with an ASCII based encoding other |
| than utf-8 (e.g. latin-1), then an appropriate ``encoding`` name must |
| be specified. Encodings that are not ASCII based (such as UCS-2) are |
| not allowed, and should be wrapped with |
| ``codecs.getreader(fp)(encoding)``, or simply decoded to a ``unicode`` |
| object and passed to ``loads()`` |
| |
| ``object_hook`` is an optional function that will be called with the |
| result of any object literal decode (a ``dict``). The return value of |
| ``object_hook`` will be used instead of the ``dict``. This feature |
| can be used to implement custom decoders (e.g. JSON-RPC class hinting). |
| |
| To use a custom ``JSONDecoder`` subclass, specify it with the ``cls`` |
| kwarg. |
| |
| """ |
| return loads(fp.read(), |
| encoding=encoding, cls=cls, object_hook=object_hook, |
| parse_float=parse_float, parse_int=parse_int, |
| parse_constant=parse_constant, **kw) |
| |
| |
| def loads(s, encoding=None, cls=None, object_hook=None, parse_float=None, |
| parse_int=None, parse_constant=None, **kw): |
| """Deserialize ``s`` (a ``str`` or ``unicode`` instance containing a JSON |
| document) to a Python object. |
| |
| If ``s`` is a ``str`` instance and is encoded with an ASCII based encoding |
| other than utf-8 (e.g. latin-1) then an appropriate ``encoding`` name |
| must be specified. Encodings that are not ASCII based (such as UCS-2) |
| are not allowed and should be decoded to ``unicode`` first. |
| |
| ``object_hook`` is an optional function that will be called with the |
| result of any object literal decode (a ``dict``). The return value of |
| ``object_hook`` will be used instead of the ``dict``. This feature |
| can be used to implement custom decoders (e.g. JSON-RPC class hinting). |
| |
| ``parse_float``, if specified, will be called with the string |
| of every JSON float to be decoded. By default this is equivalent to |
| float(num_str). This can be used to use another datatype or parser |
| for JSON floats (e.g. decimal.Decimal). |
| |
| ``parse_int``, if specified, will be called with the string |
| of every JSON int to be decoded. By default this is equivalent to |
| int(num_str). This can be used to use another datatype or parser |
| for JSON integers (e.g. float). |
| |
| ``parse_constant``, if specified, will be called with one of the |
| following strings: -Infinity, Infinity, NaN, null, true, false. |
| This can be used to raise an exception if invalid JSON numbers |
| are encountered. |
| |
| To use a custom ``JSONDecoder`` subclass, specify it with the ``cls`` |
| kwarg. |
| |
| """ |
| if (cls is None and encoding is None and object_hook is None and |
| parse_int is None and parse_float is None and |
| parse_constant is None and not kw): |
| return _default_decoder.decode(s) |
| if cls is None: |
| cls = JSONDecoder |
| if object_hook is not None: |
| kw['object_hook'] = object_hook |
| if parse_float is not None: |
| kw['parse_float'] = parse_float |
| if parse_int is not None: |
| kw['parse_int'] = parse_int |
| if parse_constant is not None: |
| kw['parse_constant'] = parse_constant |
| return cls(encoding=encoding, **kw).decode(s) |