Utility to return the specified fields of an object as a dict with fields mapped to values. Handles nested attribues specified by '__' delimiter. For JSON and stuff.

obj_to_dict.py

from typing import List, Union, Tuple, Dict, Any


def nestedattr(obj: object, field: str):
    if "__" in field:
        primary_field, remainder_field = field.split("__", 1)
        primary_field_value = getattr(obj, primary_field)
        if not primary_field_value:
            return primary_field_value
        return nestedattr(primary_field_value, remainder_field)
    else:
        return getattr(obj, field)


def obj_to_dict(
    obj: object, fields: List[Union[Tuple[str, str], str]]
) -> Dict[str, Any]:
    """Return the specified fields of an object as a dict with fields mapped to values.
    Handles nested attribues specified by '__' delimiter.
    For JSON and stuff.
    """
    return {
        (field if type(field) == str else field[1]): nestedattr(
            obj, (field if type(field) == str else field[0])
        )
        for field in fields
    }