是否可以检查频道是否存在？

Question

I'm making a Discord bot and there's a channel in my server allocated to our rules and I want this bot to automatically send a message in that channel. Is it possible to check if the channel exists? Thanks.

Answer 1

Yes you definitely can.

if (message.Content.StartsWith("!check"))
{
    SocketGuildChannel currentChannel = message.Channel as SocketGuildChannel;
    SocketGuild guild = currentChannel.Guild;

    foreach (SocketGuildChannel ch in guild.Channels)
    {
        if (ch.GetType() == typeof(SocketTextChannel)) //Checking text channels
        {
            if (ch.Name.Equals("rules"))
            {
                ISocketMessageChannel channel = (ISocketMessageChannel)ch; //Casting so we can send a message
                await channel.SendMessageAsync("This is the rules channel.");
                return;
            }
        }
    }
    await message.Channel.SendMessageAsync("Could not find the rules channel.");
    return;
}

Answer 2

Assuming you are using Discord.Net 1.0.2

If you want to have it as a command:

    [Command("check")]
    public async Task CheckChannel(string channel)
    {
        foreach (SocketGuildChannel chan in Context.Guild.Channels)
        {
            if (channel == chan.Name)
            {
                // It exists!
                ITextChannel ch = chan as ITextChannel;
                await ch.SendMessageAsync("This is the rules channel!");
            }
            else
            {
                // It doesn't exist!
                await ReplyAsync($"No channel named {channel} was found.");
            }
        }
    }

Answer 3

You could also use Linq!

[Command("check")]
public async Task CheckChannel(string channelName)
{
    //Makes the channel name NOT case sensitive
    var channel = Context.Guild?.Channels.FirstOrDefault(c => string.Equals(c.Name, channelName, StringComparison.OrdinalIgnoreCase));
    if (channel != null)
    {
        ITextChannel ch = channel as ITextChannel;
        await ch.SendMessageAsync("This is the rules channel!");
    }
    else
    {
        // It doesn't exist!
        await ReplyAsync($"No channel named {channel} was found.");
    }
}

Also a warning, This will fail in a DM because Context.Guild == null in a direct message. If you so desired, you can add this snippet inside your command!

if (Context.IsPrivate)
{
    await ReplyAsync("Cant call command from a direct message");
    return;
}