The `get_prefix` went wrong when use in DMChannel

[fiery holly]

async def get_prefix(bot, message):
        
    if isinstance(message.channel, discord.DMChannel):
        return commands.when_mentioned_or(DEFAULT_PREFIX)
      
    prefix = await bot.db.fetch('SELECT prefix FROM guilds WHERE "guild_id" = $1', message.guild.id)
        
    if len(prefix) == 0:
        await bot.db.execute('INSERT INTO guilds ("guild_id", prefix) VALUES ($1, $2)', message.guild.id, DEFAULT_PREFIX)
        prefix = DEFAULT_PREFIX
        
    else:
        prefix = prefix[0].get("prefix")
        
    return commands.when_mentioned_or(prefix)(bot, message)

class DiseaseBot(commands.AutoShardedBot):
    def __init__(self):
        super().__init__(
            command_prefix = get_prefix,
            case_insensitive = True,
            intents=discord.Intents.all(),
            help_command= None
        )
            
    async def create_db_pool(self):
        self.db = await asyncpg.create_pool(database= "DiseasesProject", user="postgres", password= DATABASE_PASSWORD)
        print("Database connection successful!")

The error says

Traceback (most recent call last):
  File "C:\Users\ACER\Documents\covidbot\venv\lib\site-packages\discord\ext\commands\bot.py", line 231, in get_prefix
    ret = list(ret)
TypeError: 'function' object is not iterable

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\ACER\Documents\covidbot\venv\lib\site-packages\discord\client.py", line 382, in _run_event
    await coro(*args, **kwargs)
  File "C:\Users\ACER\Documents\covidbot\venv\lib\site-packages\discord\ext\commands\bot.py", line 382, in on_message
    await self.process_commands(message)
  File "C:\Users\ACER\Documents\covidbot\venv\lib\site-packages\discord\ext\commands\bot.py", line 378, in process_commands
    ctx = await self.get_context(message)
  File "C:\Users\ACER\Documents\covidbot\bot.py", line 26, in get_context
    return await super().get_context(message, cls=cls)
  File "C:\Users\ACER\Documents\covidbot\venv\lib\site-packages\discord\ext\commands\bot.py", line 284, in get_context
    prefix = await self.get_prefix(message)
  File "C:\Users\ACER\Documents\covidbot\venv\lib\site-packages\discord\ext\commands\bot.py", line 238, in get_prefix
    raise TypeError(
TypeError: command_prefix must be plain string, iterable of strings, or callable returning either of these, not function

It works fine when I use in guild but in DM not.

[latent obsidian]

https://docs.pycord.dev/en/master/ext/commands/api.html#discord.ext.commands.when_mentioned_or

[fiery holly]

Can you explain more? because i think that my function return a callable function...

[latent obsidian]

the note already shows an example

This callable returns another callable, so if this is done inside a custom callable, you must call the returned callable, for example:

async def get_prefix(bot, message):
    extras = await prefixes_for(message.guild) # returns a list
    return commands.when_mentioned_or(*extras)(bot, message)```

[fiery holly]

oh okay

So from this one, it supposes to be

return commands.when_mentioned_or(DEFAULT_PREFIX)(bot, message)``` right?

[latent obsidian]

yes, you need to do another call with (bot, message)