How can I send a message to a user out of a JSON file?

Probably a very easy question to answer, but I want to send a message to a user after a certain time. For this I read his ID from a JSON. Problem with this? You cannot append a send to a str or this error is then spit out.

I have already tried to convert the whole thing, but without success. Can someone give me a hint here?

The code:

    @commands.Cog.listener()
    async def on_ready(self):
        period = 10 # 86400.0
        while 3:
            with open('work_data/statues.json') as j:
                u_data = json.load(j)
                for user in list(u_data.keys()): # read user, ID comes out if you do print(user)
                    if dt.datetime.now().timestamp() - u_data[user][0]['last_seen'] >= period:
                        await user.send(f"{user}, you haven't shown up at work for 24 hours and have been fired.") # part that doesn't work
                        await asyncio.sleep(2)
                        u_data.pop(user)
                        write_json(u_data)
                await asyncio.sleep(0.1)

The JSON:

{
    "30288509151923XXXX": [ # Last 4 numbers removed because privacy.
        {
# rest not relevant
        }
    ]
}

The error message:

Ignoring exception in on_ready
Traceback (most recent call last):
  File "C:UsersMikePycharmProjectsMikeBotvenvlibsite-packagesdisnakeclient.py", line 505, in _run_event
    await coro(*args, **kwargs)
  File "C:UsersMikePycharmProjectsMikeBotcogswork.py", line 308, in on_ready
    await user.send(f"{user}, you haven't shown up at work for 24 hours and have been fired.")
AttributeError: 'str' object has no attribute 'send'

Answer

It looks like you are using disnake instead of discord.py.

You can have a look at their docs. Here we learn something about fetch_user, get_user or getch_user which will first check the cache and then fetch the user if needed.

In your example, you can use the following:

await self.bot.getch_user(user) # asynchronous, needs to be awaited