在Python中以json格式保存数据时，日期格式会自动更改

import json
from datetime import datetime

# 自定义日期对象的序列化方式
def serialize_date(obj):
    if isinstance(obj, datetime):
        return obj.strftime("%Y-%m-%d %H:%M:%S")
    raise TypeError("Object of type 'datetime' is not JSON serializable")

data = {
    "name": "John Doe",
    "birthdate": datetime(1990, 1, 1)
}

# 保存数据到json文件
with open("data.json", "w") as file:
    json.dump(data, file, default=serialize_date)

# 从json文件加载数据
with open("data.json", "r") as file:
    loaded_data = json.load(file)

print(loaded_data["birthdate"])  # 输出：1990-01-01 00:00:00