the world's only json encoder that handles buffer message (or grpc message, I don't know)

json_utils.py

import json
from datetime import datetime
from decimal import Decimal
from flask import Response
from functools import wraps
from google.protobuf.internal import api_implementation


if api_implementation.Type() == 'cpp':
    from google.protobuf.pyext.cpp_message import GeneratedProtocolMessageType
    from google.protobuf.pyext._message import ScalarMapContainer as ScalarMap
    from google.protobuf.pyext._message import RepeatedScalarContainer as RepeatedScalarFieldContainer
    from google.protobuf.pyext._message import RepeatedCompositeContainer as RepeatedCompositeFieldContainer
else:
    from google.protobuf.internal.python_message import GeneratedProtocolMessageType
    from google.protobuf.internal.containers import ScalarMap, RepeatedScalarFieldContainer, RepeatedCompositeFieldContainer


class VersatileEncoder(json.JSONEncoder):

    def convert_grpc_types(self, obj):
        if isinstance(obj, ScalarMap):
            return dict(obj)
        if isinstance(obj, RepeatedScalarFieldContainer):
            return list(obj)
        if isinstance(type(obj), GeneratedProtocolMessageType):
            return self.default(obj)
        if isinstance(obj, RepeatedCompositeFieldContainer):
            return [self.default(o) for o in obj]
        return obj

    def default(self, obj):
        if hasattr(obj, 'to_dict'):
            return obj.to_dict()
        if isinstance(obj, datetime):
            return obj.strftime('%Y-%m-%d %H:%M:%S')
        if isinstance(obj, Decimal):
            return float(obj)
        if isinstance(obj, bytes):
            return obj.decode('utf-8')
        if isinstance(type(obj), GeneratedProtocolMessageType):
            field_names = [field.name for field in obj.DESCRIPTOR.fields]
            dic = {n: self.convert_grpc_types(getattr(obj, n)) for n in field_names}
            # need this to identify what kind of message is this
            dic['__class__'] = obj.__class__.__name__
            return dic
        return super(VersatileEncoder, self).default(obj)