Fix JSON module docs.
This commit is contained in:
Georg Brandl
parent
4b964f9c90
commit
3961f1872c
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@ -1,8 +1,8 @@
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:mod:`json` JSON encoder and decoder
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====================================
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:mod:`json` --- JSON encoder and decoder
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========================================
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.. module:: json
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:synopsis: encode and decode the JSON format
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:synopsis: Encode and decode the JSON format.
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.. moduleauthor:: Bob Ippolito <bob@redivi.com>
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.. sectionauthor:: Bob Ippolito <bob@redivi.com>
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.. versionadded:: 2.6
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@ -10,8 +10,8 @@
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JSON (JavaScript Object Notation) <http://json.org> is a subset of JavaScript
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syntax (ECMA-262 3rd edition) used as a lightweight data interchange format.
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:mod:`json` exposes an API familiar to uses of the standard library marshal and
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pickle modules.
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:mod:`json` exposes an API familiar to users of the standard library
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:mod:`marshal` and :mod:`pickle` modules.
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Encoding basic Python object hierarchies::
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@ -74,7 +74,7 @@ Specializing JSON object decoding::
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>>> json.loads('1.1', parse_float=decimal.Decimal)
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Decimal('1.1')
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Extending JSONEncoder::
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Extending :class:`JSONEncoder`::
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>>> import json
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>>> class ComplexEncoder(json.JSONEncoder):
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@ -106,7 +106,7 @@ Using json.tool from the shell to validate and pretty-print::
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.. note::
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Note that the JSON produced by this module's default settings is a subset of
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The JSON produced by this module's default settings is a subset of
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YAML, so it may be used as a serializer for that as well.
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@ -115,118 +115,55 @@ Basic Usage
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.. function:: dump(obj, fp[, skipkeys[, ensure_ascii[, check_circular[, allow_nan[, cls[, indent[, separators[, encoding[, default[, **kw]]]]]]]]]])
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Serialize *obj* as a JSON formatted stream to *fp* (a
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``.write()``-supporting file-like object).
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Serialize *obj* as a JSON formatted stream to *fp* (a ``.write()``-supporting
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file-like object).
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If *skipkeys* is ``True`` (It is ``False`` by default.), then ``dict`` keys
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that are not basic types (``str``, ``unicode``, ``int``, ``long``,
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``float``, ``bool``, ``None``) will be skipped instead of raising a
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:exc:`TypeError`.
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If *skipkeys* is ``True`` (default: ``False``), then dict keys that are not
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of a basic type (:class:`str`, :class:`unicode`, :class:`int`, :class:`long`,
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:class:`float`, :class:`bool`, ``None``) will be skipped instead of raising a
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:exc:`TypeError`.
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If *ensure_ascii* is ``False`` (It is ``True`` by default.), then the some
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chunks written to *fp* may be ``unicode`` instances, subject to normal
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Python ``str`` to ``unicode`` coercion rules. Unless ``fp.write()``
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explicitly understands ``unicode`` (as in ``codecs.getwriter()``) this is
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likely to cause an error.
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If *ensure_ascii* is ``False`` (default: ``True``), then some chunks written
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to *fp* may be :class:`unicode` instances, subject to normal Python
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:class:`str` to :class:`unicode` coercion rules. Unless ``fp.write()``
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explicitly understands :class:`unicode` (as in :func:`codecs.getwriter`) this
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is likely to cause an error.
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If *check_circular* is ``False``, then the circular reference check for
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container types will be skipped and a circular reference will result in an
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:exc:`OverflowError` (or worse).
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If *check_circular* is ``False`` (default: ``True``), then the circular
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reference check for container types will be skipped and a circular reference
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will result in an :exc:`OverflowError` (or worse).
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If *allow_nan* is ``False``, then it will be a :exc:`ValueError` to
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serialize out of range ``float`` values (``nan``, ``inf``, ``-inf``) in
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strict compliance of the JSON specification, instead of using the JavaScript
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equivalents (``NaN``, ``Infinity``, ``-Infinity``).
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If *allow_nan* is ``False`` (default: ``True``), then it will be a
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:exc:`ValueError` to serialize out of range :class:`float` values (``nan``,
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``inf``, ``-inf``) in strict compliance of the JSON specification, instead of
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using the JavaScript equivalents (``NaN``, ``Infinity``, ``-Infinity``).
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If *indent* is a non-negative integer, then JSON array elements and object
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members will be pretty-printed with that indent level. An indent level of 0
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will only insert newlines. ``None`` is the most compact representation.
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If *indent* is a non-negative integer, then JSON array elements and object
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members will be pretty-printed with that indent level. An indent level of 0
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will only insert newlines. ``None`` (the default) selects the most compact
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representation.
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If *separators* is an ``(item_separator, dict_separator)`` tuple then it
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will be used instead of the default ``(', ', ': ')`` separators. ``(',',
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':')`` is the most compact JSON representation.
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If *separators* is an ``(item_separator, dict_separator)`` tuple, then it
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will be used instead of the default ``(', ', ': ')`` separators. ``(',',
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':')`` is the most compact JSON representation.
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*encoding* is the character encoding for str instances, default is UTF-8.
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*encoding* is the character encoding for str instances, default is UTF-8.
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*default(obj)* is a function that should return a serializable version of
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obj or raise :exc:`TypeError`. The default simply raises :exc:`TypeError`.
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*default(obj)* is a function that should return a serializable version of
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*obj* or raise :exc:`TypeError`. The default simply raises :exc:`TypeError`.
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To use a custom :class:`JSONEncoder`` subclass (e.g. one that overrides the
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``.default()`` method to serialize additional types), specify it with the
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*cls* kwarg.
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To use a custom :class:`JSONEncoder`` subclass (e.g. one that overrides the
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:meth:`default` method to serialize additional types), specify it with the
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*cls* kwarg.
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.. function:: dump(obj[, skipkeys[, ensure_ascii[, check_circular[, allow_nan[, cls[, indent[, separators[, encoding[, default[, **kw]]]]]]]]]])
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.. function:: dumps(obj[, skipkeys[, ensure_ascii[, check_circular[, allow_nan[, cls[, indent[, separators[, encoding[, default[, **kw]]]]]]]]]])
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Serialize *obj* to a JSON formatted ``str``.
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Serialize *obj* to a JSON formatted :class:`str`.
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If *skipkeys* is ``True`` (It is ``False`` by default.), then ``dict`` keys
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that are not basic types (``str``, ``unicode``, ``int``, ``long``,
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``float``, ``bool``, ``None``) will be skipped instead of raising a
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:exc:`TypeError`.
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If *ensure_ascii* is ``False``, then the return value will be a ``unicode``
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instance subject to normal Python ``str`` to ``unicode`` coercion rules
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instead of being escaped to an ASCII ``str``.
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If *check_circular* is ``False``, then the circular reference check for
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container types will be skipped and a circular reference will result in an
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:exc:`OverflowError` (or worse).
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If *allow_nan* is ``False``, then it will be a :exc:`ValueError` to
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serialize out of range ``float`` values (``nan``, ``inf``, ``-inf``) in
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strict compliance of the JSON specification, instead of using the JavaScript
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equivalents (``NaN``, ``Infinity``, ``-Infinity``).
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If *indent* is a non-negative integer, then JSON array elements and object
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members will be pretty-printed with that indent level. An indent level of 0
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will only insert newlines. ``None`` is the most compact representation.
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If *separators* is an ``(item_separator, dict_separator)`` tuple then it
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will be used instead of the default ``(', ', ': ')`` separators. ``(',',
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':')`` is the most compact JSON representation.
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*encoding* is the character encoding for str instances, default is UTF-8.
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*default(obj)* is a function that should return a serializable version of
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obj or raise :exc:`TypeError`. The default simply raises :exc:`TypeError`.
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To use a custom :class:`JSONEncoder`` subclass (e.g. one that overrides the
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``.default()`` method to serialize additional types), specify it with the
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*cls* kwarg.
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.. function loads(s[, encoding[, cls[, object_hook[, parse_float[, parse_int[, parse_constant[, **kw]]]]]]])
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Deserialize *s* (a ``str`` or ``unicode`` instance containing a JSON
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document) to a Python object.
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If *s* is a ``str`` instance and is encoded with an ASCII based encoding
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other than utf-8 (e.g. latin-1) then an appropriate ``encoding`` name must be
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specified. Encodings that are not ASCII based (such as UCS-2) are not allowed
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and should be decoded to ``unicode`` first.
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*object_hook* is an optional function that will be called with the result of
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any object literal decode (a ``dict``). The return value of ``object_hook``
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will be used instead of the ``dict``. This feature can be used to implement
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custom decoders (e.g. JSON-RPC class hinting).
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*parse_float*, if specified, will be called with the string of every JSON
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float to be decoded. By default, this is equivalent to
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``float(num_str)``. This can be used to use another datatype or parser for
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JSON floats (e.g. decimal.Decimal).
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*parse_int*, if specified, will be called with the string of every JSON int
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to be decoded. By default this is equivalent to int(num_str). This can be
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used to use another datatype or parser for JSON integers (e.g. float).
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*parse_constant*, if specified, will be called with one of the following
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strings: -Infinity, Infinity, NaN, null, true, false. This can be used to
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raise an exception if invalid JSON numbers are encountered.
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To use a custom :class:`JSONDecoder` subclass, specify it with the ``cls``
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kwarg. Additional keyword arguments will be passed to the constructor of the
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class.
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If *ensure_ascii* is ``False``, then the return value will be a
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:class:`unicode` instance. The other arguments have the same meaning as in
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:func:`dump`.
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.. function load(fp[, encoding[, cls[, object_hook[, parse_float[, parse_int[, parse_constant[, **kw]]]]]]])
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@ -234,28 +171,56 @@ Basic Usage
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Deserialize *fp* (a ``.read()``-supporting file-like object containing a JSON
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document) to a Python object.
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If the contents of *fp* is encoded with an ASCII based encoding other than
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utf-8 (e.g. latin-1), then an appropriate ``encoding`` name must be
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specified. Encodings that are not ASCII based (such as UCS-2) are not
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allowed, and should be wrapped with :func:`codecs.getreader(fp)(encoding)`,
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or simply decoded to a ``unicode`` object and passed to ``loads()``
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If the contents of *fp* are encoded with an ASCII based encoding other than
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UTF-8 (e.g. latin-1), then an appropriate *encoding* name must be specified.
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Encodings that are not ASCII based (such as UCS-2) are not allowed, and
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should be wrapped with ``codecs.getreader(fp)(encoding)``, or simply decoded
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to a :class:`unicode` object and passed to :func:`loads`.
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*object_hook* is an optional function that will be called with the result of
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any object literal decode (a ``dict``). The return value of *object_hook*
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will be used instead of the ``dict``. This feature can be used to implement
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custom decoders (e.g. JSON-RPC class hinting).
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any object literal decode (a :class:`dict`). The return value of
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*object_hook* will be used instead of the :class:`dict`. This feature can be used
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to implement custom decoders (e.g. JSON-RPC class hinting).
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*parse_float*, if specified, will be called with the string of every JSON
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float to be decoded. By default, this is equivalent to ``float(num_str)``.
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This can be used to use another datatype or parser for JSON floats
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(e.g. :class:`decimal.Decimal`).
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*parse_int*, if specified, will be called with the string of every JSON int
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to be decoded. By default, this is equivalent to ``int(num_str)``. This can
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be used to use another datatype or parser for JSON integers
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(e.g. :class:`float`).
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*parse_constant*, if specified, will be called with one of the following
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strings: ``'-Infinity'``, ``'Infinity'``, ``'NaN'``, ``'null'``, ``'true'``,
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``'false'``. This can be used to raise an exception if invalid JSON numbers
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are encountered.
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To use a custom :class:`JSONDecoder` subclass, specify it with the ``cls``
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kwarg. Additional keyword arguments will be passed to the constructor of the
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kwarg. Additional keyword arguments will be passed to the constructor of the
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class.
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.. function loads(s[, encoding[, cls[, object_hook[, parse_float[, parse_int[, parse_constant[, **kw]]]]]]])
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Deserialize *s* (a :class:`str` or :class:`unicode` instance containing a JSON
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document) to a Python object.
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If *s* is a :class:`str` instance and is encoded with an ASCII based encoding
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other than UTF-8 (e.g. latin-1), then an appropriate *encoding* name must be
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specified. Encodings that are not ASCII based (such as UCS-2) are not
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allowed and should be decoded to :class:`unicode` first.
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The other arguments have the same meaning as in :func:`dump`.
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Encoders and decoders
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---------------------
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.. class:: JSONDecoder([encoding[, object_hook[, parse_float[, parse_int[, parse_constant[, strict]]]]]])
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Simple JSON decoder
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Simple JSON decoder.
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Performs the following translations in decoding by default:
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@ -282,50 +247,52 @@ Encoders and decoders
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It also understands ``NaN``, ``Infinity``, and ``-Infinity`` as their
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corresponding ``float`` values, which is outside the JSON spec.
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*encoding* determines the encoding used to interpret any ``str`` objects
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decoded by this instance (utf-8 by default). It has no effect when decoding
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``unicode`` objects.
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*encoding* determines the encoding used to interpret any :class:`str` objects
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decoded by this instance (UTF-8 by default). It has no effect when decoding
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:class:`unicode` objects.
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Note that currently only encodings that are a superset of ASCII work,
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strings of other encodings should be passed in as ``unicode``.
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Note that currently only encodings that are a superset of ASCII work, strings
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of other encodings should be passed in as :class:`unicode`.
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*object_hook*, if specified, will be called with the result of every JSON
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object decoded and its return value will be used in place of the given
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``dict``. This can be used to provide custom deserializations (e.g. to
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:class:`dict`. This can be used to provide custom deserializations (e.g. to
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support JSON-RPC class hinting).
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*parse_float*, if specified, will be called with the string of every JSON
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float to be decoded. By default this is equivalent to float(num_str). This
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can be used to use another datatype or parser for JSON floats
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(e.g. decimal.Decimal).
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float to be decoded. By default, this is equivalent to ``float(num_str)``.
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This can be used to use another datatype or parser for JSON floats
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(e.g. :class:`decimal.Decimal`).
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*parse_int*, if specified, will be called with the string of every JSON int
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to be decoded. By default this is equivalent to int(num_str). This can be
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used to use another datatype or parser for JSON integers (e.g. float).
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to be decoded. By default, this is equivalent to ``int(num_str)``. This can
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be used to use another datatype or parser for JSON integers
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(e.g. :class:`float`).
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*parse_constant*, if specified, will be called with one of the following
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strings: -Infinity, Infinity, NaN, null, true, false. This can be used to
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raise an exception if invalid JSON numbers are encountered.
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strings: ``'-Infinity'``, ``'Infinity'``, ``'NaN'``, ``'null'``, ``'true'``,
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``'false'``. This can be used to raise an exception if invalid JSON numbers
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are encountered.
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.. method:: decode(s)
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Return the Python representation of *s* (a ``str`` or ``unicode`` instance
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containing a JSON document)
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Return the Python representation of *s* (a :class:`str` or
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:class:`unicode` instance containing a JSON document)
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.. method:: raw_decode(s)
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Decode a JSON document from *s* (a ``str`` or ``unicode`` beginning with a
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JSON document) and return a 2-tuple of the Python representation and the
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index in *s* where the document ended.
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Decode a JSON document from *s* (a :class:`str` or :class:`unicode`
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beginning with a JSON document) and return a 2-tuple of the Python
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representation and the index in *s* where the document ended.
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This can be used to decode a JSON document from a string that may have
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extraneous data at the end.
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This can be used to decode a JSON document from a string that may have
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extraneous data at the end.
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.. class:: JSONEncoder([skipkeys[, ensure_ascii[, check_circular[, allow_nan[, sort_keys[, indent[, separators[, encoding[, default]]]]]]]]])
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Extensible JSON <http://json.org> encoder for Python data structures.
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Extensible JSON encoder for Python data structures.
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Supports the following objects and types by default:
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@ -348,7 +315,7 @@ Encoders and decoders
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+-------------------+---------------+
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To extend this to recognize other objects, subclass and implement a
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``.default()`` method with another method that returns a serializable object
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:meth:`default` method with another method that returns a serializable object
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for ``o`` if possible, otherwise it should call the superclass implementation
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(to raise :exc:`TypeError`).
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@ -356,31 +323,32 @@ Encoders and decoders
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attempt encoding of keys that are not str, int, long, float or None. If
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*skipkeys* is ``True``, such items are simply skipped.
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If *ensure_ascii* is ``True``, the output is guaranteed to be ``str`` objects
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with all incoming unicode characters escaped. If *ensure_ascii* is
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``False``, the output will be unicode object.
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If *ensure_ascii* is ``True`` (the default), the output is guaranteed to be
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:class:`str` objects with all incoming unicode characters escaped. If
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*ensure_ascii* is ``False``, the output will be a unicode object.
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If *check_circular* is ``True`` (the default), then lists, dicts, and custom
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encoded objects will be checked for circular references during encoding to
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prevent an infinite recursion (which would cause an :exc:`OverflowError`).
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Otherwise, no such check takes place.
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If *allow_nan* is ``True`` (the default), then ``NaN``, ``Infinity``, and ``-Infinity``
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will be encoded as such. This behavior is not JSON specification compliant,
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but is consistent with most JavaScript based encoders and decoders.
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Otherwise, it will be a :exc:`ValueError` to encode such floats.
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If *allow_nan* is ``True`` (the default), then ``NaN``, ``Infinity``, and
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``-Infinity`` will be encoded as such. This behavior is not JSON
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specification compliant, but is consistent with most JavaScript based
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encoders and decoders. Otherwise, it will be a :exc:`ValueError` to encode
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such floats.
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If *sort_keys* is ``True`` (the default), then the output of dictionaries
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will be sorted by key; this is useful for regression tests to ensure that
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JSON serializations can be compared on a day-to-day basis.
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If *indent* is a non-negative integer (It is ``None`` by default.), then JSON
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If *indent* is a non-negative integer (it is ``None`` by default), then JSON
|
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array elements and object members will be pretty-printed with that indent
|
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level. An indent level of 0 will only insert newlines. ``None`` is the most
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compact representation.
|
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|
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If specified, *separators* should be a (item_separator, key_separator) tuple.
|
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The default is ``(', ', ': ')``. To get the most compact JSON
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If specified, *separators* should be an ``(item_separator, key_separator)``
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tuple. The default is ``(', ', ': ')``. To get the most compact JSON
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representation, you should specify ``(',', ':')`` to eliminate whitespace.
|
||||
|
||||
If specified, *default* is a function that gets called for objects that can't
|
||||
|
|
@ -413,7 +381,7 @@ Encoders and decoders
|
|||
|
||||
.. method:: encode(o)
|
||||
|
||||
Return a JSON string representation of a Python data structure, *o*. For
|
||||
Return a JSON string representation of a Python data structure, *o*. For
|
||||
example::
|
||||
|
||||
>>> JSONEncoder().encode({"foo": ["bar", "baz"]})
|
||||
|
|
@ -423,9 +391,7 @@ Encoders and decoders
|
|||
.. method:: iterencode(o)
|
||||
|
||||
Encode the given object, *o*, and yield each string representation as
|
||||
available.
|
||||
|
||||
For example::
|
||||
available. For example::
|
||||
|
||||
for chunk in JSONEncoder().iterencode(bigobject):
|
||||
mysocket.write(chunk)
|
||||
|
|
|
|||
Loading…
Reference in New Issue