On Nov 2, 2018, at 12:28 PM, Calvin Spealman <cspea...@redhat.com> wrote:
> Second, JSON is a specific serialization format that explicitly rejects
> datetime objects in *all* the languages with JSON libraries. You can only
> use date objects in JSON if you control or understand both serialization
> and deserialization ends and have an agreed representation.
I would hardly say that "rejects datetime objects in *all* languages..."
Most Javascript implementations do handle dates correctly which is a bit
telling for me. For example, the Mozilla reference calls out Date as
explicitly supported [1]. I also ran it through the Javascript console and
repl.it to make sure that it wasn't a doc glitch [2].
Go also supports serialization of date/times as shown in this repl.it
session [3]. As does rust, though rust doesn't use ISO-8601 [4].
That being said, I'm +1 on adding support for serializing datetime.date and
datetime.datetime *but* I'm -1 on automatically deserializing anything that
looks like a ISO-8601 in json.load*. The asymmetry is the only thing that
kept me from bringing this up previously.
What about implementing this as a protocol?
The Javascript implementation of JSON.stringify looks for a method named
toJSON() when it encounters a non-primitive type and uses the result for
serialization. This would be a pretty easy lift in json.JSONEncoder.default:
class JSONEncoder(object):
def default(self, o):
if hasattr(o, 'to_json'):
return o.to_json(self)
raise TypeError(f'Object of type {o.__class__.__name__} '
f'is not JSON serializable')
I would recommend passing the JSONEncoder instance in to ``to_json()`` as I
did in the snippet. This makes serialization much easier for classes since
they do not have to assume a particular set of JSON serialization options.
Is this something that is PEP-worthy or is a PR with a simple flag to enable
the functionality in JSON encoder enough?
- cheers, dave.
[1]:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify
[2]: https://repl.it/@dave_shawley/OffensiveParallelResource
[3]: https://repl.it/@dave_shawley/EvenSunnyForce
[4]:
https://play.rust-lang.org/?version=stable&mode=debug&edition=2015&gist=73de1454da4ac56900cde37edb0d6c8f
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