Using Slash Commands and Interactions

Slash commands and interactions are a newer feature of Discord which allow bot's commands to be registered centrally within the system and for users to easily explore and get help with avaialble commands through the client itself.

To add a slash command you should use the dpp::cluster::global_command_create method for global commands (available to all guilds) or dpp::cluster::guild_command_create to create a local command (available only to one guild).

When a user issues these commands the reply will arrive via the on_interaction_create event which you can hook, and take action when you see your commands. It is possible to reply to an interaction by using either the dpp::interaction_create_t::reply method, or by manually instantiating an object of type dpp::interaction_response and attaching a dpp::message object to it.

dpp::interaction_create_t::reply has two overloaded versions of the method, one of which accepts simple std::string replies, for basic text-only messages (if your message is 'ephemeral' you must use this) and one which accepts a dpp::message for more advanced replies. Please note that at present, Discord only supports a small subset of message and embed features within an interaction response object.

Note

A later version of the library will include a built in command handler system which will be able to integrate with slash commands and interactions, making this process even more seamless.

#include <dpp/dpp.h>
#include <fmt/format.h>
#include <iomanip>
 
int main(int argc, char const *argv[])
{
    dpp::cluster bot("token");
 
    /* The interaction create event is fired when someone issues your commands */
    bot.on_interaction_create([&bot](const dpp::interaction_create_t & cmd) {
        /* Check which command they ran */
        if (cmd.command.data.name == "blep") {
            /* Fetch a parameter value from the command parameters */
            std::string animal = std::get<std::string>(cmd.get_parameter("animal"));
            /* Reply to the command. There is an overloaded version of this
             * call that accepts a dpp::message so you can send embeds.
             */
            cmd.reply(dpp::ir_channel_message_with_source, fmt::format("Blep! You chose {}", animal));
        }
    });
 
    bot.on_ready([&bot](const dpp::ready_t & event) {
        dpp::slashcommand newcommand;
 
        /* Create a new global command on ready event */
        newcommand
            .set_name("blep")
            .set_description("Send a random adorable animal photo")
            .set_application_id(bot.me.id);
            .add_option(
                dpp::command_option(dpp::co_string, "animal", "The type of animal", true).
                    add_choice(dpp::command_option_choice("Dog", std::string("animal_dog"))).
                    add_choice(dpp::command_option_choice("Cat", std::string("animal_cat"))).
                    add_choice(dpp::command_option_choice("Penguin", std::string("animal_penguin")
                )
            )
        );
 
        /* Register the command */
        bot.global_command_create(newcommand);
 
    bot.start(false);
    return 0;
}