json file I/O for python3

json_io.py

# -*-coding: utf-8 -*-
import os
import json


def read_json(filename):
    if not os.path.isfile(filename):
        raise FileExistsError("[error] {0} not found.".format(filename))
    with open(filename) as f:
        return json.load(f)


def write_json(obj, filename):
    if obj is None:
        raise ValueError("[error] obj parameter cannot null.")
    if not isinstance(obj, dict):
        raise TypeError("[error] obj type must be dictionary.")
    with open(filename, mode='w') as f:
        json.dump(obj, f, ensure_ascii=False)


if __name__ == '__main__':
    jsonStr = read_json("./test.json")
    print(jsonStr)
    
    try:
        write_json(jsonStr, "./write_test.json")
        print("success")
    except Exception as e:
        print("failed.")

test.json

{
    "name": "Taro",
    "age": 24,
    "japanese": "たろう"
}