A generic function to expand flat dicts

expand_flatdict_to_tree.py

def expand_flatdict_to_tree(dict, sep = '_', to_lower = True):
    tree = {}
    
    for src, val in dict.items():
        ref = tree

        if to_lower:
            src = src.lower()
    
        for i, part in enumerate(src.split(sep)):
            if part not in ref:
                ref[part] = {}
            if i == len(src.split(sep)) -1:
                ref[part] = val # we cannot do ref = val after loop, as assignment to the ref itself will be passed by assignment
                break
            ref = ref[part] # update nest reference
    
    return tree


flat_dict = {
    'LOGLEVEL': 'INFO',
    'DB_ENABLED': True,
    'DB_CONNECTOR_HOST': 'localhost',
    'DB_CONNECTOR_USER': 'root',
}

print (expand_flatdict_to_tree(flat_dict))

# {
#     'loglevel': 'INFO',
#     'db': {
#         'enabled': True,
#         'connector': {
#             'host': 'localhost',
#             'user': 'root'
#         }
#     }
# }