trans normal dict to MongoDB dot natation format dict

dict2dot.py

#!/usr/bin/env python
# coding: utf-8

def dict2dot(foo, bar):
    for k, v in foo.items():
        if not isinstance(v, dict):
            bar[k] = v
            continue
        for kk, vv in v.items():
            dict2dot({'{}.{}'.format(k, kk): vv}, bar)

foo = {
    'a0': 1,
    'a1': {
        'b0': 2,
        'b1': 3,
        'b2': {
            'c0':4
        },
        'b3': 6,
        'b4': {
            'c0':7
        }
    },
    'a2': 5
}

bar = {}
print foo
dict2dot(foo, bar)
print bar

"""
Output:

{'a1': {'b4': {'c0': 7}, 'b0': 2, 'b1': 3, 'b2': {'c0': 4}, 'b3': 6}, 'a0': 1, 'a2': 5}
{'a1.b4.c0': 7, 'a1.b3': 6, 'a1.b1': 3, 'a1.b0': 2, 'a1.b2.c0': 4, 'a0': 1, 'a2': 5}
"""