Dynamically modify command prefix in Discord.NET bot - C# CommandService

Other Questions Discord bot
1

I’m working on a Discord bot using C# and need help with updating the command prefix dynamically. Currently I have this setup:

UsingCommands(config =>
{
     config.PrefixChar = _database.CurrentPrefix;
     config.AllowMentionPrefix = true;
});

The prefix gets loaded from my database initially. I also created a command to change the prefix:

_commandService.CreateCommand("setprefix").Parameter("newPrefix").Do(async response =>
{
    char newPrefix;
    if (!char.TryParse(response.Args[0], out newPrefix))
    {
        await response.User.SendMessage($"Invalid format. Use: {_database.CurrentPrefix}setprefix <char>");
    }
    else
    { 
        _database.UpdatePrefix(newPrefix);
        await response.User.SendMessage($"Command prefix changed to {_database.CurrentPrefix}");
    }
});

The issue is that while the database gets updated successfully, the CommandService still uses the old prefix. I tried using CustomPrefixHandler but couldn’t get it working properly. How can I make the CommandService recognize the new prefix without restarting the bot?

2

yep, totally get what ur dealing with. I faced the same issue, ended up writing a custom solution instead of using the build-in prefix. just check the prefix from the db for each msg and handle it manually, it’s way more flexible that way.

3

The CommandService config is essentially immutable after initialization, which explains why changes to the prefix aren’t reflecting. I tackled this by implementing a custom prefix resolver within the message handling process. Rather than relying on the default PrefixChar, I validate messages against the prefix stored in my database before processing them with ExecuteAsync. By intercepting the MessageReceived event, you can dynamically retrieve the current prefix and manually adjust the message content to remove it, allowing for immediate prefix updates without the need to restart the bot.

4

You’re hitting a limitation with the older Discord.NET CommandService. Once you set the PrefixChar during startup, you can’t change it dynamically. Your best bet is creating a custom message handler. Override the MessageReceived event and check prefixes against your database directly. Pull the prefix from each message and manually call the command with ExecuteAsync. This lets you swap prefixes without restarting the bot - I’ve used this approach in my own projects and it works great.