flask_restful - TypeError: Object of type Record is not JSON serializable - python-3.x

Question

I try to provide a custom object inside a rest api, created with flask_restful.
Object: Record
import json
class Record():
#CLASS RECORD
def __init__(self, DateTime, DateTimeText, Status, Icon, Temp):
#INITIALIZE
self.DateTime = DateTime
self.DateTimeText = DateTimeText
self.Status = Status
self.Icon = Icon
self.Temp = Temp
def __repr__(self):
return json.dumps(self, default=lambda o: o.__dict__, sort_keys=False, indent=4)
Result: print(record)
{
"DateTime": 1583949600,
"DateTimeText": "2020-03-11 18:00:00",
"Status": "Clouds",
"Icon": "04n",
"Temp": 280.57
}
Rest API:
from flask_restful import Resource, Api, reqparse
class _Weather(Resource):
#WEATHER
def get(self):
#GET WEATHER
return {'value': Weather.Record}
self.Api.add_resource(_Weather, '/api/weather')
Error:
all other calls works fine, only me custom object (http://localhost:80/api/weather) returns the following error stack:
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask\app.py", line 2463, in __call__
return self.wsgi_app(environ, start_response)
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask\app.py", line 2449, in wsgi_app
response = self.handle_exception(e)
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask_restful\__init__.py", line 272, in error_router
return original_handler(e)
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask_cors\extension.py", line 161, in wrapped_function
return cors_after_request(app.make_response(f(*args, **kwargs)))
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask\app.py", line 1866, in handle_exception
reraise(exc_type, exc_value, tb)
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask\_compat.py", line 38, in reraise
raise value.with_traceback(tb)
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask\app.py", line 2446, in wsgi_app
response = self.full_dispatch_request()
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask\app.py", line 1951, in full_dispatch_request
rv = self.handle_user_exception(e)
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask_restful\__init__.py", line 272, in error_router
return original_handler(e)
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask_cors\extension.py", line 161, in wrapped_function
return cors_after_request(app.make_response(f(*args, **kwargs)))
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask\app.py", line 1820, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask\_compat.py", line 38, in reraise
raise value.with_traceback(tb)
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask\app.py", line 1949, in full_dispatch_request
rv = self.dispatch_request()
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask\app.py", line 1935, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask_restful\__init__.py", line 472, in wrapper
return self.make_response(data, code, headers=headers)
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask_restful\__init__.py", line 501, in make_response
resp = self.representations[mediatype](data, *args, **kwargs)
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\flask_restful\representations\json.py", line 21, in output_json
dumped = dumps(data, **settings) + "\n"
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\json\__init__.py", line 234, in dumps
return cls(
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\json\encoder.py", line 201, in encode
chunks = list(chunks)
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\json\encoder.py", line 431, in _iterencode
yield from _iterencode_dict(o, _current_indent_level)
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\json\encoder.py", line 405, in _iterencode_dict
yield from chunks
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\json\encoder.py", line 438, in _iterencode
o = _default(o)
File "C:\Users\Martin\AppData\Local\Programs\Python\Python38-32\Lib\json\encoder.py", line 179, in default
raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type Record is not JSON serializable
I try a lot of different approaches, found here on stack. Non of these works for my.
Python 3.8.2

Answer 1

You have a couple of options here.
Make a tojson() method for your Record class and call that for your return value. It will basically just return the underlying __dict__ for your object.
def tojson(self):
return self.__dict__
Pass Weather.Record.__dict__ directly as your return value
So your return statement will look like one of these:
return {'value': Weather.Record.__dict__}
Or, using jsonify from Flask:
return jsonify({'value': 'Weather.Record.__dict__})
Or replace Weather.Record.__dict__ with Weather.Record.tojson() if you add that method to the class.