Python dataclass from dict

dataclass_from_dict.py

from dataclasses import dataclass, is_dataclass, asdict as dataclass_as_dict, fields as dataclass_fields

def dataclass_from_dict(cls, src):
    kwargs = {}
    fields_lookup = {field.name: field for field in dataclass_fields(cls)}
    for field_name, value in src.items():
        field = fields_lookup.get(field_name)
        if not field:
            #logger.warning('config field %s not found for class %s', field_name, cls.__name__)
            continue
        if field.init:
            if is_dataclass(field.type):
                kwargs[field_name] = dataclass_from_dict(field.type, value)
            elif isinstance(value, list):
                data_type = field.type
                list_cls = data_type.__args__[0]
                if is_dataclass(list_cls):
                    kwargs[field_name] = [dataclass_from_dict(list_cls, v) for v in value]
                else:
                    kwargs[field_name] = value
            elif isinstance(value, dict):
                data_type = field.type
                #key_cls = data_type.__args__[0]
                val_cls = data_type.__args__[1]

                if is_dataclass(val_cls):
                    kwargs[field_name] = {k: dataclass_from_dict(val_cls, v) for k, v in value.items()}
                else:
                    kwargs[field_name] = value
            else:
                kwargs[field_name] = value
    return cls(**kwargs)


if __name__ == '__main__':
  @dataclass
  class Bar:
      x: int

  @dataclass
  class Foo:
      a: int
      b: str
      c: list[Bar]
      d: dict[str, Bar]

  foo = Foo(10, 'bbbb', [Bar(12), Bar(13)], {'a': Bar(14), 'b': Bar(15)})
  foo_dict = dataclass_as_dict(foo)
  print(foo)
  print(foo_dict)
  print(dataclass_from_dict(Foo, foo_dict))