[New-bugs-announce] [issue42791] There is no way to json encode object to str.

Artyom Kaltovich report at bugs.python.org
Wed Dec 30 15:22:51 EST 2020

New submission from Artyom Kaltovich <kaltovichartyom at gmail.com>:


At first I want to say thank you for all your efforts in python development. I really appreciate it. :)

I am trying to convert custom object to json. 

But, I've found a problem. JSONEncoder has ``default`` method for converting custom objects to some primitives and ``encode`` for converting structures.

But what if I want to return completed json string? I can't do it in ``default``, because JSONEncoder will think it is string and encode it accordingly later in ``iterencode`` method.

Then I tried redefine encode, but it is called with the dict(array_name=default(o)) so I should convert the dict as a whole and basically reimplement all conversions (for int, float, and lists of course).

Did I missed something or there is no way to do it?

I suggest to introduce another method, e.g. encode_obj and call it there:

   o = _default(o)
   yield from _iterencode(o, _current_indent_level)
   o = _encode_obj(_default(o))
   yield from _iterencode(o, _current_indent_level)

If you are agree I would be happy to implement it.

Best Regards,

components: Library (Lib)
messages: 384085
nosy: kaltovichartyom
priority: normal
severity: normal
status: open
title: There is no way to json encode object to str.

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