Introduction

.NET Generic Host
Bare Bones

Adding application commands with the .NET Generic Host is very easy. Use AddApplicationCommands<TInteraction, TContext>(IServiceCollection) to add the application command service to your host builder. Then, use AddSlashCommand, AddUserCommand or AddMessageCommand to add an application command using the minimal APIs way and/or use AddModules(IHost, Assembly) to add application command modules from an assembly. You also need to use UseGatewayEventHandlers(IHost) to bind the service event handlers.

using Microsoft.Extensions.Hosting;

using NetCord;
using NetCord.Hosting.Gateway;
using NetCord.Hosting.Services;
using NetCord.Hosting.Services.ApplicationCommands;
using NetCord.Rest;
using NetCord.Services.ApplicationCommands;

var builder = Host.CreateApplicationBuilder(args);

builder.Services
    .AddDiscordGateway()
    .AddApplicationCommands<ApplicationCommandInteraction, ApplicationCommandContext>();

var host = builder.Build();

// Add commands using minimal APIs
host.AddSlashCommand("ping", "Ping!", () => "Pong!")
    .AddUserCommand("Username", (User user) => user.Username)
    .AddMessageCommand("Length", (RestMessage message) => message.Content.Length.ToString());

// Add commands from modules
host.AddModules(typeof(Program).Assembly);

// Add handlers to handle the commands
host.UseGatewayEventHandlers();

await host.RunAsync();

First, add the following lines to the using section.

using NetCord.Rest;
using NetCord.Services;
using NetCord.Services.ApplicationCommands;

Now, it's time to create ApplicationCommandService<TContext> instance and add application commands to it. You can do it by using AddSlashCommand, AddUserCommand or AddMessageCommand to add an application command using the minimal APIs way and/or by using AddModules(Assembly) to add application command modules from an assembly.

// Create the application command service
ApplicationCommandService<ApplicationCommandContext> applicationCommandService = new();

// Add commands using minimal APIs
applicationCommandService.AddSlashCommand("ping", "Ping!", () => "Pong!");
applicationCommandService.AddUserCommand("Username", (User user) => user.Username);
applicationCommandService.AddMessageCommand("Length", (RestMessage message) => message.Content.Length.ToString());

// Add commands from modules
applicationCommandService.AddModules(typeof(Program).Assembly);

We can add a command handler now. If you used other context than SlashCommandContext, you should change the interaction type of the handler to the appropriate one.

// Add the handler to handle interactions
client.InteractionCreate += async interaction =>
{
    // Check if the interaction is an application command interaction
    if (interaction is not ApplicationCommandInteraction applicationCommandInteraction)
        return;

    // Execute the command
    var result = await applicationCommandService.ExecuteAsync(new ApplicationCommandContext(applicationCommandInteraction, client));

    // Check if the execution failed
    if (result is not IFailResult failResult)
        return;

    // Return the error message to the user if the execution failed
    try
    {
        await interaction.SendResponseAsync(InteractionCallback.Message(failResult.Message));
    }
    catch
    {
    }
};

Now, we should send the commands to Discord, to make them usable. Add the following line under the handler:

// Create the commands so that you can use them in the Discord client
await applicationCommandService.CreateCommandsAsync(client.Rest, client.Id);

The Final Product

Program.cs

using NetCord;
using NetCord.Gateway;
using NetCord.Rest;
using NetCord.Services;
using NetCord.Services.ApplicationCommands;

GatewayClient client = new(new BotToken("Token from Discord Developer Portal"), new GatewayClientConfiguration()
{
    Intents = default,
});

// Create the application command service
ApplicationCommandService<ApplicationCommandContext> applicationCommandService = new();

// Add commands using minimal APIs
applicationCommandService.AddSlashCommand("ping", "Ping!", () => "Pong!");
applicationCommandService.AddUserCommand("Username", (User user) => user.Username);
applicationCommandService.AddMessageCommand("Length", (RestMessage message) => message.Content.Length.ToString());

// Add commands from modules
applicationCommandService.AddModules(typeof(Program).Assembly);

// Add the handler to handle interactions
client.InteractionCreate += async interaction =>
{
    // Check if the interaction is an application command interaction
    if (interaction is not ApplicationCommandInteraction applicationCommandInteraction)
        return;

    // Execute the command
    var result = await applicationCommandService.ExecuteAsync(new ApplicationCommandContext(applicationCommandInteraction, client));

    // Check if the execution failed
    if (result is not IFailResult failResult)
        return;

    // Return the error message to the user if the execution failed
    try
    {
        await interaction.SendResponseAsync(InteractionCallback.Message(failResult.Message));
    }
    catch
    {
    }
};

// Create the commands so that you can use them in the Discord client
await applicationCommandService.CreateCommandsAsync(client.Rest, client.Id);

client.Log += message =>
{
    Console.WriteLine(message);
    return default;
};

await client.StartAsync();
await Task.Delay(-1);

Note

If you don't see the commands in Discord, try refreshing the Discord client using Ctrl + R on PC or ⌘ + R on Mac.

Important

Please note that names of slash commands must be lowercase.

Example Module

Here you can see an example module showing how to use modules with application commands.

using NetCord;
using NetCord.Rest;
using NetCord.Services.ApplicationCommands;

namespace MyBot;

public class ExampleModule : ApplicationCommandModule<ApplicationCommandContext>
{
    [SlashCommand("pong", "Pong!")]
    public static string Pong() => "Ping!";

    [UserCommand("ID")]
    public static string Id(User user) => user.Id.ToString();

    [MessageCommand("Timestamp")]
    public static string Timestamp(RestMessage message) => message.CreatedAt.ToString();
}

Table of Contents

Introduction

Note

Important

Example Module