simpleml.orm.serializing

Module to define the classes that support serialization for all JSON columns

A lot of persistable subclasses try to persist objects that cannot be natively serialized in a database. This attempts to define a custom pattern to serialize them and subsequently deserialize on load

Module Contents

Classes

JSONSerializer

Extensible JSON <http://json.org> encoder for Python data structures.

Functions

custom_dumps(data)
custom_loads(data)
object_hook(data, ignore_dicts=False)

Attributes

__author__

simpleml.orm.serializing.__author__ = Elisha Yadgaran

class simpleml.orm.serializing.JSONSerializer(skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, sort_keys=False, indent=None, separators=None, encoding='utf-8', default=None, use_decimal=True, namedtuple_as_object=True, tuple_as_array=True, bigint_as_string=False, item_sort_key=None, for_json=False, ignore_nan=False, int_as_string_bitcount=None, iterable_as_array=False)

Bases: simplejson.JSONEncoder

Extensible JSON <http://json.org> encoder for Python data structures.

Supports the following objects and types by default:

Python	JSON
dict, namedtuple	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).

Constructor for JSONEncoder, with sensible defaults.

If skipkeys is false, then it is a TypeError to attempt encoding of keys that are not str, int, long, float 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 unicode characters escaped. If ensure_ascii is false, the output will be unicode object.

If check_circular is true, then lists, dicts, and custom encoded objects will be checked for circular references during encoding to prevent an infinite recursion (which would cause an OverflowError). Otherwise, no such check takes place.

If allow_nan is true, then NaN, Infinity, and -Infinity will be encoded as such. This behavior is not JSON specification compliant, but is consistent with most JavaScript based encoders and decoders. Otherwise, it will be a ValueError to encode such floats.

If sort_keys is true, then the output of dictionaries will be sorted by key; this is useful for regression tests to ensure that JSON serializations can be compared on a day-to-day basis.

If indent is a string, then JSON array elements and object members will be pretty-printed with a newline followed by that string repeated for each level of nesting. None (the default) selects the most compact representation without any newlines. For backwards compatibility with versions of simplejson earlier than 2.1.0, an integer is also accepted and is converted to a string with that many spaces.

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.

If encoding is not None, then all input strings will be transformed into unicode using that encoding prior to JSON-encoding. The default is UTF-8.

If use_decimal is true (default: True), decimal.Decimal will be supported directly by the encoder. For the inverse, decode JSON with parse_float=decimal.Decimal.

If namedtuple_as_object is true (the default), objects with _asdict() methods will be encoded as JSON objects.

If tuple_as_array is true (the default), tuple (and subclasses) will be encoded as JSON arrays.

If iterable_as_array is true (default: False), any object not in the above table that implements __iter__() will be encoded as a JSON array.

If bigint_as_string is true (not the default), ints 2**53 and higher or lower than -2**53 will be encoded as strings. This is to avoid the rounding that happens in Javascript otherwise.

If int_as_string_bitcount is a positive number (n), then int of size greater than or equal to 2**n or lower than or equal to -2**n will be encoded as strings.

If specified, item_sort_key is a callable used to sort the items in each dictionary. This is useful if you want to sort items other than in alphabetical order by key.

If for_json is true (not the default), objects with a for_json() method will use the return value of that method for encoding as JSON instead of the object.

If ignore_nan is true (default: False), then out of range float values (nan, inf, -inf) will be serialized as null in compliance with the ECMA-262 specification. If true, this will override allow_nan.

default(self, obj)

Implement this method in a subclass such that it returns a serializable object for o, or calls the base implementation (to raise a TypeError).

For example, to support arbitrary iterators, you could implement default like this:

def default(self, o):
    try:
        iterable = iter(o)
    except TypeError:
        pass
    else:
        return list(iterable)
    return JSONEncoder.default(self, o)

Parameters

obj (Any) –

Return type

Union[float, int, str]

simpleml.orm.serializing.custom_dumps(data)

simpleml.orm.serializing.custom_loads(data)

simpleml.orm.serializing.object_hook(data, ignore_dicts=False)