Allow namedtuple to be JSON encoded as dict

[Zack]

BPO	23473
Nosy	@rhettinger, @pitrou, @ericvsmith, @ezio-melotti, @serhiy-storchaka
Superseder	bpo-12657: Cannot override JSON encoding of basic type subclasses

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2015-02-18.15:11:02.259>
created_at = <Date 2015-02-17.16:52:36.166>
labels = ['type-bug']
title = 'Allow namedtuple to be JSON encoded as dict'
updated_at = <Date 2015-02-18.15:11:02.257>
user = 'https://bugs.python.org/Zack'

bugs.python.org fields:

activity = <Date 2015-02-18.15:11:02.257>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2015-02-18.15:11:02.259>
closer = 'serhiy.storchaka'
components = []
creation = <Date 2015-02-17.16:52:36.166>
creator = 'Zack--'
dependencies = []
files = []
hgrepos = []
issue_num = 23473
keywords = []
message_count = 4.0
messages = ['236139', '236170', '236171', '236177']
nosy_count = 6.0
nosy_names = ['rhettinger', 'pitrou', 'eric.smith', 'ezio.melotti', 'serhiy.storchaka', 'Zack--']
pr_nums = []
priority = 'normal'
resolution = 'duplicate'
stage = None
status = 'closed'
superseder = '12657'
type = 'behavior'
url = 'https://bugs.python.org/issue23473'
versions = ['Python 2.7', 'Python 3.2', 'Python 3.3', 'Python 3.4', 'Python 3.5', 'Python 3.6']

[Zack]

We used to be able to override _iterencode prior to 2.7 to get our namedtuples to be encoded as dict using json.dump(s) but now we can not.

Namedtuples are automatically encoded as list but it would be more logical and convenient to have them encoded as dict

[ericvsmith]

Can you post a code snippet that used to work, but now does not?

[Zack]

From memory, something along the lines of

from json import JSONEncoder

class ExtendedJSONEncoder(JSONEncoder):

    def _iterencode(self, o, markers=None):
        if isinstance(o, tuple) and hasattr(obj, '_fields'):
            gen = self._iterencode_dict(o.__dict__, markers)
        else:
            gen = JSONEncoder._iterencode(self, o, markers)
        for chunk in gen:
            yield chunk

[serhiy-storchaka]

This is a duplicate of bpo-12657.