xoutil.json - Encode and decode the JSON format

Extensions to the json standard library module.

It just adds the ability to encode/decode datetimes. But you should use the JSONEncoder yourself.

You may use this module as drop-in replacement to Python’s json. Also it contains definitions to use C library JSON speedups or Python replacements in case that library is not installed in your system.

xoutil.json.dump()

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 true (the default), all non-ASCII characters in the output are escaped with \uXXXX sequences, and the result is a str instance consisting of ASCII characters only. If ensure_ascii is False, some chunks written to fp may be unicode instances. This usually happens because the input contains unicode strings or the encoding parameter is used. 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. Since the default item separator is ', ', the output might include trailing whitespace when indent is specified. You can use separators=(',', ': ') to avoid this.

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.

If sort_keys is True (default: False), then the output of dictionaries will be sorted by key.

To use a custom JSONEncoder subclass (e.g. one that overrides the .default() method to serialize additional types), specify it with the cls kwarg; otherwise JSONEncoder is used.

xoutil.json.dumps()

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, all non-ASCII characters are not escaped, and the return value may be a unicode instance. See dump for details.

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. Since the default item separator is ', ', the output might include trailing whitespace when indent is specified. You can use separators=(',', ': ') to avoid this.

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.

If sort_keys is True (default: False), then the output of dictionaries will be sorted by key.

To use a custom JSONEncoder subclass (e.g. one that overrides the .default() method to serialize additional types), specify it with the cls kwarg; otherwise JSONEncoder is used.

xoutil.json.load()

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).

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 that rely on the order that the key and value pairs are decoded (for example, collections.OrderedDict will remember the order of insertion). 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.

xoutil.json.loads()

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).

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 that rely on the order that the key and value pairs are decoded (for example, collections.OrderedDict will remember the order of insertion). 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 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; otherwise JSONDecoder is used.

class xoutil.json.JSONDecoder

Simple JSON <http://json.org> decoder

Performs the following translations in decoding by default:

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.

decode()

Return the Python representation of s (a str or unicode instance containing a JSON document)

raw_decode()

Decode a JSON document from s (a str or unicode beginning with a JSON document) and return a 2-tuple of the Python representation and the index in s where the document ended.

This can be used to decode a JSON document from a string that may have extraneous data at the end.

class xoutil.json.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).

We also support:

• datetime, date and time values, which are translated to strings using ISO format.
• Decimal values, which are represented as a string representation.
• Iterables, which are represented as lists.