New subject: [issue18820] json.dump() ignores its 'default' option when serializing dictionary keys

23 Aug 2013

      New submission from July Tikhonov:

According to documentation of json.dump(), concerning its 'default' option:

default(obj) is a function that should return a serializable version of obj or raise TypeError. The default simply raises TypeError.

But this function is actually never applied to serialized dictionary keys:
...
...
...
def default(obj):
...  if isinstance(obj, bytes):
...   return obj.decode('ascii')
...  raise ValueError
... 
json.dumps(b'asdf')
Traceback (most recent call last):
...
TypeError: b'asdf' is not JSON serializable
json.dumps(b'asdf', default=default)
'"asdf"'
json.dumps({b'asdf' : 1}, default=default)
Traceback (most recent call last):
...
TypeError: keys must be a string
json.dumps({1 : b'asdf'}, default=default)
'{"1": "asdf"}'
(bytes are used purely for the purpose of example)
Such behavior should be either documented or corrected.
Patch correcting python implementation of json attached.

----------
assignee: docs@python
components: Documentation, Library (Lib)
files: json-default-dict-keys.diff
keywords: patch
messages: 195957
nosy: docs@python, july
priority: normal
severity: normal
status: open
title: json.dump() ignores its 'default' option when serializing dictionary keys
type: enhancement
versions: Python 3.4
Added file: http://bugs.python.org/file31436/json-default-dict-keys.diff

_______________________________________
Python tracker <report@bugs.python.org>
<http://bugs.python.org/issue18820>
_______________________________________

[issue18820] json.dump() ignores its 'default' option when serializing dictionary keys

July Tikhonov

July Tikhonov

July Tikhonov

Ezio Melotti

July Tikhonov

Chris Rebert

Erwin Mayer

Berker Peksag

Serhiy Storchaka

Erwin Mayer

tags

participants (6)