from collections import abc
from collections.abc import Hashable, Mapping, MutableMapping
from copy import deepcopy
from typing import Any, TypeVar, Union, cast
K = TypeVar("K", bound=Hashable)
L = TypeVar("L", bound=Hashable)
[docs]
def deep_update(
dest: MutableMapping[K, Any], update: Mapping[L, Any]
) -> MutableMapping[Union[K, L], Any]:
"""
Recursively update one JSON structure with another.
Only dives into nested dicts; lists get replaced completely.
If the original value is a dictionary and the new value is not, or vice versa,
we also replace the value completely.
"""
dest_int = cast(MutableMapping[Union[K, L], Any], dest)
for k, v_update in update.items():
v_dest = dest_int.get(k)
if isinstance(v_update, abc.Mapping) and isinstance(v_dest, abc.MutableMapping):
deep_update(v_dest, v_update)
else:
dest_int[k] = deepcopy(v_update)
return dest_int