Cannot convert json

Question

I'm trying to convert flask request to json

from flask import request
import json

req_data = request.get_json(force=True)
json_data = json.dumps(req_data)
json.loads(json_data)

But when I try this I have :

TypeError: Object of type set is not JSON serializable

Can you explain me ?

Answer 1

By default the json.dumps serialize obj to a JSON formatted str using conversion table

To extend this to recognize other objects, subclass json.JSONEncoder class and implement a default() method with another method that returns a serializable object for o if possible.

>>> import json
>>>
>>> class SetEncoder(json.JSONEncoder):
...     def default(self, o):
...             if isinstance(o, set):
...                     # Do your serailzation here...
...             return json.JSONEncoder.default(self, o)

Then you could do json.dumps(obj, cls=SetEncoder).

For example,

>>> import json
>>> my_obj = {1: {1,2, 3}}
>>>
>>> class SetEncoder(json.JSONEncoder):
...     def default(self, o):
...         if isinstance(o, set):
...             return list(o)
...         return json.JSONEncoder.default(self, o)
...
>>> print(json.dumps(my_obj, cls=SetEncoder))
{"1": [1, 2, 3]}