Attaching a file to a message

Attached files must be locally stored.

To attach a file to a message, you can upload a local image.

D++ has this helper function to read a file: dpp::utility::read_file.

An example program:

#include <dpp/dpp.h>
 
int main() {
    dpp::cluster bot("token");
 
    /* Message handler to look for a command called !file */
    bot.on_message_create([&bot](const dpp::message_create_t &event) {
        if (event.msg.content == "!file") {
            // create a message
            dpp::message msg(event.msg.channel_id, "Hey there, i've got a new file!");
 
            // attach the file
            msg.set_file_content(dpp::utility::read_file("path_to_your_file.txt"));
            
            /*
             * alternatively, you can put any other name in here.
             * This name doesn't have to be the same as the uploaded filename.
             * But it should have the same file extension.
             */
            msg.set_filename("file.txt");
 
            // send the message
            bot.message_create(msg);
        }
    });
 
    bot.start(false);
    return 0;
}

Attachments via an url aren't possible. But there's a workaround for. You can download the file and then attach it to the message.

To make requests, D++ also has a helper function: dpp::cluster::request.

The following example program shows how to request a file and attach it to a message.

#include <dpp/dpp.h>
 
int main() {
    dpp::cluster bot("token");
 
    /* Message handler to look for a command called !file */
    bot.on_message_create([&bot](const dpp::message_create_t &event) {
        if (event.msg.content == "!file") {
            // request an image
            bot.request("https://dpp.dev/DPP-Logo.png", dpp::m_get, [&bot, channel_id = event.msg.channel_id](const dpp::http_request_completion_t & httpRequestCompletion) {
 
                // create a message
                dpp::message msg(channel_id, "This is my new attachment:");
 
                // attach the image on success
                if (httpRequestCompletion.status == 200) {
                    msg.set_file_content(httpRequestCompletion.body);
                    msg.set_filename("example-image.png"); // give the file a name
                }
 
                // send the message
                bot.message_create(msg);
            });
        }
    });
 
    bot.start(false);
    return 0;
}

Here's another example of how to add a local image to an embed.

Upload the image in the same message as the embed and then reference it in the embed.

#include <dpp/dpp.h>
 
int main() {
    dpp::cluster bot("token");
 
    /* Message handler to look for a command called !file */
    bot.on_message_create([&bot](const dpp::message_create_t &event) {
        if (event.msg.content == "!file") {
            // create a message
            dpp::message msg(event.msg.channel_id, "");
 
            // attach the file to the message
            msg.set_file_content(dpp::utility::read_file("path_to_your_image.jpg"));
            msg.set_filename("image.jpg");
 
            dpp::embed embed;
            embed.set_image("attachment://image.jpg"); // reference to the attached file
            msg.add_embed(embed);
 
            // send the message
            bot.message_create(msg);
        }
    });
 
    bot.start(false);
    return 0;
}