Python JSON encoder to support datetime?

Question

is there any elegant way to make Python JSON encoder support datetime? some 3rd party module or easy hack?

I am using tornado's database wrapper to fetch some rows from db to generate a json. The query result includes a regular MySQL timestamp column.

It's quite annoying that Python's default json encoder doesn't support its own datetime type, which is so common in all kinds of database queries.

I don't want to modify Python's own json encoder. any good practice? Thanks a lot!

ps: I found a dirty hack by modifying the Python JSON encoder default method:

Change:

def default(self, o):     raise TypeError(repr(o) + " is not JSON serializable") 

To:

def default(self, o):     from datetime import date     from datetime import datetime     if isinstance(o, datetime):         return o.isoformat()     elif isinstance(o, date):         return o.isoformat()     else:         raise TypeError(repr(o) + " is not JSON serializable") 

well, it will be a temporary solution just for dev environment.

But for long term solution or production environment, this is quite ugly, and I have to do the modification every time I deploy to a new server.

Is there a better way? I do not want to modify Python code itself, neither Tornado source code. Is there something I can do with my own project code to make this happen? preferably in one pace.

Thanks a lot!

Answer 1

json.dumps(thing, default=str)

Answer 2

The docs suggest subclassing JSONEncoder and implementing your own default method. Seems like you're basically there, and it's not a "dirty hack".

The reason dates aren't handled by the default encoder is there is no standard representation of a date in JSON. Some people are using the format /Date(1198908717056)/, but I prefer ISO format personally.

import json import datetime   class DateTimeEncoder(json.JSONEncoder):      def default(self, obj):         if isinstance(obj, (datetime.datetime, datetime.date, datetime.time)):             return obj.isoformat()         elif isinstance(obj, datetime.timedelta):             return (datetime.datetime.min + obj).time().isoformat()          return super(DateTimeEncoder, self).default(obj)  now = datetime.datetime.now() encoder = DateTimeEncoder() encoder.encode({"datetime": now, "date": now.date(), "time": now.time()}) > {"datetime": "2019-07-02T16:17:09.990126", "date": "2019-07-02", "time": "16:17:09.990126"}