Parse json via python NamedTuple

json_namedtuple.py

import hashlib
import json
from decimal import Decimal
from typing import Any, Dict, Type

from typing_inspect import get_args, get_generic_bases, is_generic_type, is_union_type  # type: ignore

Json = Dict[str, Any]


def json_decoder(nt: Type, data: Json) -> Dict:
    """
Takes a NamedTuple class object and Json, and converts the json into a dict ready to be constructed into the
NamedTuple, or excepts if there is not sufficient data. You can then do `MyNamedTuple(**result)`
    """

    decoded = {}
    field_types = nt._field_types
    for key in field_types:
        value = data.get(key)
        if value is None:
            possible_types = get_args(field_types[key])
            if len(possible_types) < 2 or type(None) not in possible_types:  # confirm the field is optional
                raise ValueError(
                    "Error decoding Json for {nt}. key '{key}' was 'None' but not listed as optional field.".format(
                        nt=nt, key=key))
        else:
            field_type = field_types[key]
            if is_generic_type(field_type):
                field_type = get_generic_bases(field_type)[0]
            elif is_union_type(field_type):
                field_type = get_args(field_types[key])[0]
            value = field_type(value)
        decoded[key] = value
    return decoded


def dict_md5(obj: Json) -> str:
    # sort_keys=True so that ordering of keys doesn't change the md5 value.
    json_obj = json.dumps(obj, sort_keys=True, cls=SmartEncoder).encode('utf-8')
    return hashlib.md5(json_obj).hexdigest()


class SmartEncoder(json.JSONEncoder):
    def default(self, o: Any) -> Any:
        if isinstance(o, set):
            return sorted(list(o))
        if isinstance(o, Decimal):
            return str(o)
        return super(SmartEncoder, self).default(o)