simplejson
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.
simplejson exposes an API familiar to uses of the standard library marshal and pickle modules.
Encoding basic Python object hierarchies:
>>> import simplejson
>>> simplejson.dumps(['foo', {'bar': ('baz', None, 1.0, 2)}])
'["foo", {"bar": ["baz", null, 1.0, 2]}]'
>>> print simplejson.dumps("\"foo\bar")
"\"foo\bar"
>>> print simplejson.dumps(u'\u1234')
"\u1234"
>>> print simplejson.dumps('\\')
"\\"
>>> print simplejson.dumps({"c": 0, "b": 0, "a": 0}, sort_keys=True)
{"a": 0, "b": 0, "c": 0}
>>> from StringIO import StringIO
>>> io = StringIO()
>>> simplejson.dump(['streaming API'], io)
>>> io.getvalue()
'["streaming API"]'
Compact encoding:
>>> import simplejson
>>> simplejson.dumps([1,2,3,{'4': 5, '6': 7}], separators=(',',':'))
'[1,2,3,{"4":5,"6":7}]'
Pretty printing:
>>> import simplejson
>>> print simplejson.dumps({'4': 5, '6': 7}, sort_keys=True, indent=4)
{
"4": 5,
"6": 7
}
Decoding JSON:
>>> import simplejson
>>> simplejson.loads('["foo", {"bar":["baz", null, 1.0, 2]}]')
[u'foo', {u'bar': [u'baz', None, 1.0, 2]}]
>>> simplejson.loads('"\\"foo\\bar"')
u'"foo\x08ar'
>>> from StringIO import StringIO
>>> io = StringIO('["streaming API"]')
>>> simplejson.load(io)
[u'streaming API']
Specializing JSON object decoding:
>>> import simplejson
>>> def as_complex(dct):
... if '__complex__' in dct:
... return complex(dct['real'], dct['imag'])
... return dct
...
>>> simplejson.loads('{"__complex__": true, "real": 1, "imag": 2}',
... object_hook=as_complex)
(1+2j)
Extending JSONEncoder:
>>> import simplejson >>> class ComplexEncoder(simplejson.JSONEncoder): ... def default(self, obj): ... if isinstance(obj, complex): ... return [obj.real, obj.imag] ... return simplejson.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', ']']
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.
Functions
f dump(obj, fp, skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, cls=None, indent=None, separators=None, encoding='utf-8', **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.
To use a custom JSONEncoder subclass (e.g. one that overrides the .default() method to serialize additional types), specify it with the cls kwarg.
f dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, cls=None, indent=None, separators=None, encoding='utf-8', **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.
To use a custom JSONEncoder subclass (e.g. one that overrides the .default() method to serialize additional types), specify it with the cls kwarg.
f load(fp, encoding=None, cls=None, object_hook=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.
f loads(s, encoding=None, cls=None, object_hook=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).
To use a custom JSONDecoder subclass, specify it with the cls kwarg.
Classes
C JSONEncoder(...) ...
Extensible JSON <http://json.org> encoder for Python data structures.
Supports the following objects and types by default:
| Python | JSON |
|---|---|
| dict | object |
| list, tuple | array |
| str, unicode | string |
| int, long, float | number |
| True | true |
| False | false |
| None | null |
To extend this to recognize other objects, subclass and implement a .default() method with another method that returns a serializable object for o if possible, otherwise it should call the superclass implementation (to raise TypeError).
This class contains 5 members.
C JSONDecoder(...) ...
Simple JSON <http://json.org> decoder
Performs the following translations in decoding:
| JSON | Python |
|---|---|
| object | dict |
| array | list |
| string | unicode |
| number (int) | int, long |
| number (real) | float |
| true | True |
| false | False |
| null | None |
It also understands NaN, Infinity, and -Infinity as their corresponding float values, which is outside the JSON spec.
This class contains 4 members.
See the source for more information.