walrus_and_data_classes.py

import re
from dataclasses import dataclass, fields
from typing import Dict

CAMEL_CASE_RE = re.compile(r'([a-z])([A-Z])')


@dataclass(frozen=True)
class ApiGatewayRequest:
    headers: Dict[str, str]
    body: str
    path_parameters: Dict[str, str]

    @classmethod
    def from_dict(cls, dict_) -> "ApiGatewayRequest":
        valid_fields = {field.name for field in fields(ApiGatewayRequest)}
        converted_dict = {
            normalized_key: value
            for (key, value) in dict_.items()
            if (normalized_key := camel_case_to_snake_case(key)) in valid_fields
        }
        return ApiGatewayRequest(**converted_dict)


def camel_case_to_snake_case(name: str) -> str:
    return CAMEL_CASE_RE.sub(r"\1_\2", name).lower()