superjson 0.0.6

Extendable json encode/decode library.

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Welcome to ``superjson`` Documentation
===============================================================================
Features:

1. Support for ``date``, ``datetime``, ``set``, ``OrderedDict``, ``deque``, ``numpy.ndarray``, that the original `json <https://docs.python.org/3/library/json.html>`_ module can not serialize. `See example <Other data types_>`_.
2. Easy to extend to support any custom data type. `See example <Extend_>`_.
3. Allow ``// double slash started comments``, ``# Pound key started comments`` style comment in json file (Good for human/machine readable config file). `See example <Comment_>`_.
4. Provide a ``compress`` option to reduce the data size. `See example <Compression_>`_.
5. Advance file I/O utility method can prevent **overwrite**, **interruption**, and provide **auto compression by file extension**. `See example <Advance file I/O utility method_>`_.


Quick Links
-----------

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Built-in Support for many popular data type
-------------------------------------------------------------------------------
Original `json <https://docs.python.org/3/library/json.html>`_ module doesn't support ``date``, ``datetime``, ``set``, ``OrderedDict``, ``deque``, ``numpy.ndarray``, but ``superjson`` does! **If you want me to add support for other data type**, please `submit here <https://github.com/MacHu-GWU/superjson-project/issues>`_.

.. code-block:: python

>>> from collections import OrderedDict, deque
>>> from datetime import date, datetime
>>> from superjson import json
>>> import numpy as np

>>> data = {
... "int": 1,
... "str": "Hello",
... "bytes": "Hello".encode("utf-8"),
... "date": date(2010, 1, 1),
... "datetime": datetime(2020, 1, 1, 18, 30, 0, 500),
... "set": set([
... datetime(2000, 1, 1),
... datetime(2000, 1, 2),
... ]),
... "deque": deque([
... deque([1, 2]),
... deque([3, 4]),
... ]),
... "ordereddict": OrderedDict([
... ("b", OrderedDict([("b", 1), ("a", 2)])),
... ("a", OrderedDict([("b", 1), ("a", 2)])),
... ]),
... "array": np.array([
... [1, 2],
... [1.1, 2.2],
... ["a", "b"],
... [datetime.now(), datetime.now()],
... ]),
... }

>>> json.dumps(data, pretty=True)


Extend
-------------------------------------------------------------------------------
You can extend your Encoder/Decoder in this way:

1. Make your ``MyJson`` inherit from ``superjson.SuperJson``.
2. Define encode method and decode method in this name convention ``dump_xxx``, ``load_xxx``.
3. dumper method has to dump object to a json serializable dictionary, and use "$<class_name>" as the key.
4. dumper and loader method must have a second argument ``class_name``, it must have a default value equals to the class name you want to support. there's a method ``get_class_name`` can help you to find out what is the correct class name.

Example:

.. code-block:: python

# Add support to pathlib.Path
>>> from pathlib import Path
>>> from superjson import SuperJson, get_class_name

>>> class MySuperJson(SuperJson):
... # dumper method has three input argument, self, obj and class_name
... def dump_Path(self, obj, class_name="pathlib.Path"):
... return {"$" + class_name: str(obj.absolute())}
...
... # loader method has three input argument, self, dct and class_name
... def load_Path(self, dct, class_name="pathlib.Path"):
... return Path(dct["$" + class_name])
...
... def dump_PosixPath(self, obj, class_name="pathlib.PosixPath"):
... return {"$" + class_name: str(obj.absolute())}
...
... def load_PosixPath(self, dct, class_name="pathlib.PosixPath"):
... return Path(dct["$" + class_name])
...
... def dump_WindowsPath(self, obj, class_name="pathlib.WindowsPath"):
... return {"$" + class_name: str(obj.absolute())}
...
... def load_WindowsPath(self, dct, class_name="pathlib.WindowsPath"):
... return Path(dct["$" + class_name])

>>> json = MySuperJson()

>>> p = Path(__file__)
>>> class_name = get_class_name(p) # this method can help you find your pathlib.PosixPath
>>> s = json.dumps(p)
>>> s
{"$pathlib.WindowsPath": "C:\\Users\\admin\\superjson-project\\README.rst"}
>>> p1 = json.loads(s)
>>> p1
C:\\Users\\admin\\superjson-project\\README.rst


Comment
-------------------------------------------------------------------------------
You can add comments to your json file, and ``superjson`` can still read it!

.. code-block:: json

>>> s= \
"""
{
# This is host
"host": "127.0.0.1",
"port": 8080 // This is port
}
"""
>>> config = json.loads(s, ignore_comments=True)
>>> config
{"host": "127.0.0.1", "port": 8080}


Compression
-------------------------------------------------------------------------------
Compress your json file is easy.

.. code-block:: python

>>> import sys
>>> data = {str(i): i for i in range(1000)}

# Compress when dump to string
>>> s = json.dumps(data, compress=True)

# Decompress when load from compressed string
>>> data1 = json.loads(s, decompress=True)

# Auto compress when dump to file
>>> json.dump(data, "data.gz") # "data.json" will not been compressed

# Auto decompress when load from file
>>> json.load("data.gz")

# compare
>>> s1 = json.dumps(data)
>>> s2 = json.dumps(data, compress=True)
>>> sys.getsizeof(s1)
11829

>>> sys.getsizeof(s2)
5809


Advance file I/O utility method
-------------------------------------------------------------------------------
If your program is interrupted while writing, you got an incomplete file, and **you also lose the original file**! To solve this issue, ``json.safe_dump(data, abspath)`` method first write json to a temporary file, then rename to what you expect, and silently overwrite old one. This can **guarantee atomic write operation**.

.. code-block:: python

>>> data = dict(a=1, b=2, c=3)
# it first write to "data.gz.tmp", when it's done, overwrite the
# original "data.gz" file
>>> json.safe_dump(data, "data.gz")

More options for ``dump``, ``safe_dump``, ``load`` can be found `HERE <http://www.wbh-doc.com.s3.amazonaws.com/superjson/_superjson.html#superjson._superjson.SuperJson.dump>`_.


.. _install:

Install
-------------------------------------------------------------------------------

``superjson`` is released on PyPI, so all you need is:

.. code-block:: console

$ pip install superjson

To upgrade to latest version:

.. code-block:: console

$ pip install --upgrade superjson