json (package)

JSON (JavaScript Object Notation) <https://json.org> is a subset of
JavaScript syntax (ECMA-262 3rd edition) used as a lightweight data
interchange format.

:mod:`json` exposes an API familiar to users of the standard library
:mod:`marshal` and :mod:`pickle` modules.  It is derived from a
version of the externally maintained simplejson library.

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
    >>> mydict = {'4': 5, '6': 7}
    >>> json.dumps([1,2,3,mydict], separators=(',', ':'))
    '[1,2,3,{"4":5,"6":7}]'

Pretty printing::

    >>> import json
    >>> print(json.dumps({'4': 5, '6': 7}, sort_keys=True, indent=4))
    {
        "4": 5,
        "6": 7
    }

Decoding JSON::

    >>> import json
    >>> obj = ['foo', {'bar': ['baz', None, 1.0, 2]}]
    >>> json.loads('["foo", {"bar":["baz", null, 1.0, 2]}]') == obj
    True
    >>> json.loads('"\\"foo\\bar"') == '"foo\x08ar'
    True
    >>> from io import StringIO
    >>> io = StringIO('["streaming API"]')
    >>> json.load(io)[0] == 'streaming API'
    True

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)
    >>> from decimal import Decimal
    >>> json.loads('1.1', parse_float=Decimal) == Decimal('1.1')
    True

Specializing JSON object encoding::

    >>> import json
    >>> def encode_complex(obj):
    ...     if isinstance(obj, complex):
    ...         return [obj.real, obj.imag]
    ...     raise TypeError(f'Object of type {obj.__class__.__name__} '
    ...                     f'is not JSON serializable')
    ...
    >>> json.dumps(2 + 1j, default=encode_complex)
    '[2.0, 1.0]'
    >>> json.JSONEncoder(default=encode_complex).encode(2 + 1j)
    '[2.0, 1.0]'
    >>> ''.join(json.JSONEncoder(default=encode_complex).iterencode(2 + 1j))
    '[2.0, 1.0]'


Using json.tool from the shell to validate and pretty-print::

    $ echo '{"json":"obj"}' | python -m json.tool
    {
        "json": "obj"
    }
    $ echo '{ 1.2:3.4}' | python -m json.tool
    Expecting property name enclosed in double quotes: line 1 column 3 (char 2)

Classes

JSONDecodeError

Subclass of ValueError with the following additional properties:

    msg: The unformatted error message
    doc: The JSON document being parsed
    pos: The start index of doc where parsing failed
    lineno: The line corresponding to pos
    colno: The column corresponding to pos

with_traceback(...)

  Exception.with_traceback(tb) --
      set self.__traceback__ to tb and return self.

args = <attribute 'args' of 'BaseException' objects>

JSONDecoder

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

    Performs the following translations in decoding by default:

    +---------------+-------------------+
    | JSON          | Python            |
    +===============+===================+
    | object        | dict              |
    +---------------+-------------------+
    | array         | list              |
    +---------------+-------------------+
    | string        | str               |
    +---------------+-------------------+
    | number (int)  | int               |
    +---------------+-------------------+
    | 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(self, s, _w=<built-in method match of re.Pattern object at 0x7f75e2e72a80>)

  Return the Python representation of ``s`` (a ``str`` instance
          containing a JSON document).

raw_decode(self, s, idx=0)

  Decode a JSON document from ``s`` (a ``str`` 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.

JSONEncoder

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

    Supports the following objects and types by default:

    +-------------------+---------------+
    | Python            | JSON          |
    +===================+===============+
    | dict              | object        |
    +-------------------+---------------+
    | list, tuple       | array         |
    +-------------------+---------------+
    | str               | string        |
    +-------------------+---------------+
    | int, 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``).

default(self, o)

  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)
                  # Let the base class default method raise the TypeError
                  return JSONEncoder.default(self, o)

encode(self, o)

  Return a JSON string representation of a Python data structure.

          >>> from json.encoder import JSONEncoder
          >>> JSONEncoder().encode({"foo": ["bar", "baz"]})
          '{"foo": ["bar", "baz"]}'

iterencode(self, o, _one_shot=False)

  Encode the given object and yield each string
          representation as available.

          For example::

              for chunk in JSONEncoder().iterencode(bigobject):
                  mysocket.write(chunk)

item_separator = ', '

key_separator = ': '

Functions

detect_encoding

detect_encoding(b)

dump

dump(obj, fp, *, skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, cls=None, indent=None, separators=None, default=None, sort_keys=False, **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``, ``int``, ``float``, ``bool``, ``None``) will be skipped
      instead of raising a ``TypeError``.

      If ``ensure_ascii`` is false, then the strings written to ``fp`` can
      contain non-ASCII characters if they appear in strings contained in
      ``obj``. Otherwise, all such characters are escaped in JSON strings.

      If ``check_circular`` is false, then the circular reference check
      for container types will be skipped and a circular reference will
      result in an ``RecursionError`` (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 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.

      ``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.

dumps

dumps(obj, *, skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, cls=None, indent=None, separators=None, default=None, sort_keys=False, **kw)

  Serialize ``obj`` to a JSON formatted ``str``.

      If ``skipkeys`` is true then ``dict`` keys that are not basic types
      (``str``, ``int``, ``float``, ``bool``, ``None``) will be skipped
      instead of raising a ``TypeError``.

      If ``ensure_ascii`` is false, then the return value can contain non-ASCII
      characters if they appear in strings contained in ``obj``. Otherwise, all
      such characters are escaped in JSON strings.

      If ``check_circular`` is false, then the circular reference check
      for container types will be skipped and a circular reference will
      result in an ``RecursionError`` (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 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.

      ``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.

load

load(fp, *, cls=None, object_hook=None, parse_float=None, parse_int=None, parse_constant=None, object_pairs_hook=None, **kw)

  Deserialize ``fp`` (a ``.read()``-supporting file-like object containing
      a JSON document) to a Python object.

      ``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.  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.

loads

loads(s, *, cls=None, object_hook=None, parse_float=None, parse_int=None, parse_constant=None, object_pairs_hook=None, **kw)

  Deserialize ``s`` (a ``str``, ``bytes`` or ``bytearray`` instance
      containing a JSON document) to a Python object.

      ``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.  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.
      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.

Modules