deep update for python dicts

dict_utils.py

import copy
import itertools


def update_list_by_dict(target: list, value: dict):
    """
    Updates a list using keys from dictionary
    May be helpful if you want a fuzzy update of a list
    If key greater than list size, list will be extended
    If list value is dict, it's deep updated
    """
    for k, v in value.items():
        idx = int(k)
        if idx >= len(target):
            target.extend(itertools.repeat(None, idx - len(target) + 1))
        if isinstance(target[idx], dict) and isinstance(v, dict):
            deepupdate(target[idx], v)
        else:
            target[idx] = v


def deepupdate(target: dict, update: dict):
    """Deep update target dict with update
    For each k,v in update: if k doesn't exist in target, it is deep copied from
    update to target.
    Nested lists are extend if you update by the list and updated if you update by dictionary
    """
    for k, v in update.items():
        curr_val = None
        if isinstance(target, dict):
            if k not in target:
                target[k] = copy.deepcopy(v)

            curr_val = target[k]

        if isinstance(curr_val, list):
            if isinstance(v, list):
                curr_val.extend(copy.deepcopy(v))
            elif isinstance(v, dict):
                update_list_by_dict(curr_val, v)
            else:
                curr_val.extend(v)
        elif isinstance(curr_val, dict):
            deepupdate(target[k], v)
        elif isinstance(curr_val, set):
            if not k in target:
                target[k] = v.copy()
            else:
                target[k].update(v.copy())
        else:
            target[k] = copy.copy(v)

test_dict_utils.py

from .dict_utils import deepupdate, update_list_by_dict


def test_update_list_by_dict():
    l = []
    update_list_by_dict(l, {0: 1, 3: 4})
    assert l == [1, None, None, 4]
    update_list_by_dict(l, {2: 3})
    assert l == [1, None, 3, 4]
    update_list_by_dict(l, {0: 0})
    assert l == [0, None, 3, 4]
    update_list_by_dict(l, {0: {'k1': {'k1.1': 'v1.1', 'k1.2': 'v1.2'}}})
    assert l == [{'k1': {'k1.1': 'v1.1', 'k1.2': 'v1.2'}}, None, 3, 4]
    update_list_by_dict(l, {0: {'k1': {'k1.1': 'v1.1*'}}})
    assert l == [{'k1': {'k1.1': 'v1.1*', 'k1.2': 'v1.2'}}, None, 3, 4]


def test_deepupdate():
    d = {}
    deepupdate(d, {'k': 'v'})
    assert d == {'k': 'v'}
    deepupdate(d, {'k': {'k1': 1, 'k2': 2}})
    assert d == {'k': {'k1': 1, 'k2': 2}}
    deepupdate(d, {'k': {'k1': 0, }})
    assert d == {'k': {'k1': 0, 'k2': 2}}
    deepupdate(d, {'l': []})
    assert d == {'k': {'k1': 0, 'k2': 2}, 'l': []}
    deepupdate(d, {'l': [1]})
    assert d == {'k': {'k1': 0, 'k2': 2}, 'l': [1]}
    deepupdate(d, {'l': {0: 2}})
    assert d == {'k': {'k1': 0, 'k2': 2}, 'l': [2]}
    deepupdate(d, {'l': {3: 3}})
    assert d == {'k': {'k1': 0, 'k2': 2}, 'l': [2, None, None, 3]}
    deepupdate(d, {'l': {0: {'k1': {'k1.1': 'v1.1', 'k1.2': 'v1.2'}}}})
    assert d == {'k': {'k1': 0, 'k2': 2}, 'l': [{'k1': {'k1.1': 'v1.1', 'k1.2': 'v1.2'}}, None, None, 3]}
    deepupdate(d, {'l': {0: {'k1': {'k1.1': 'v1.1*'}}}})
    assert d == {'k': {'k1': 0, 'k2': 2}, 'l': [{'k1': {'k1.1': 'v1.1*', 'k1.2': 'v1.2'}}, None, None, 3]}