Messaging a user a bot does not know - node.js

Question

I am using the Slack RTM node client and having a bit of an issue with DM's. Say a user joins the channel who has never DM'ed the bot before, the user types a command in the channel that the bot usually will respond to and by default the bot responds in a private message to the user. However, the bot cannot do this because the dataStore does not contain any DM data for this user. Code sample below...
rtm.on(RTM_EVENTS.MESSAGE, function (message) {
user = rtm.getUserById(message.user);
console.log(user); // It gets the user object fine
dm = rtm.getDMByName(user.name);
console.log(dm); // This is always undefined unless the user has DM'ed the bot previously
});
Is there a way around this? I can't seem to find anything in the docs or code to suggest there might be.

Answer 1

You can use the im.open method of the web API. Here's roughly how you'd do it with #slack/client (untested, apologies in advance!):
var webClient = new WebClient(token);
...
rtm.on(RTM_EVENTS.MESSAGE, function (message) {
var dm = rtm.getDMById(message.user);
if (dm) {
console.log(`Already open IM: ${dm}`);
// send a message or whatever you want to do here
} else {
webClient.im.open(message.user, function (err, result) {
var dm = result.channel.id;
console.log(`Newly opened IM: ${dm}`);
// send a message or whatever you want to do here
});
}
});