Extensible JSON encoder for Python data structures.
Supports the following objects and types by default:
| Python |
JSON |
| dict |
object |
| list, tuple |
array |
| str |
string |
| int, float, int- & float-derived Enums |
number |
| True |
true |
| False |
false |
| None |
null |
Changed in version 3.4: Added support for int- and float-derived Enum classes.
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).
If skipkeys is false (the default), then it is a TypeError to
attempt encoding of keys that are not str, int,
float or None. If skipkeys is true, such items are simply
skipped.
If ensure_ascii is true (the default), the output is guaranteed to
have all incoming non-ASCII characters escaped. If ensure_ascii is
false, these characters will be output as-is.
If check_circular is true (the default), 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 (the default), 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 (default: False), 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 non-negative integer or string, then JSON array elements and
object members will be pretty-printed with that indent level. An indent level
of 0, negative, or "" will only insert newlines. None (the default)
selects the most compact representation. Using a positive integer indent
indents that many spaces per level. If indent is a string (such as "\t"),
that string is used to indent each level.
Changed in version 3.2: Allow strings for indent in addition to integers.
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.
Changed in version 3.4: Use (',', ': ') as default if indent is not None.
If specified, default should be 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 not specified, TypeError
is raised.
Changed in version 3.6: All parameters are now keyword-only.
-
default(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 json.JSONEncoder.default(self, o)
-
encode(o)
Return a JSON string representation of a Python data structure, o. For
example:
>>> json.JSONEncoder().encode({"foo": ["bar", "baz"]})
'{"foo": ["bar", "baz"]}'
-
iterencode(o)
Encode the given object, o, and yield each string representation as
available. For example:
for chunk in json.JSONEncoder().iterencode(bigobject):
mysocket.write(chunk)