Slack SDK for Java

Shortcuts

Shortcuts are an evolution of slash commands, surfaced in both the composer menu and the quick switcher. Shortcuts allow users to trigger your app’s workflows from intuitive surface areas within Slack.

Your app has 3 seconds to call ack(), which acknowledges a shortcut request is received from Slack.

Global / Message Shortcuts

Slack App Configuration

To enable shortcuts, visit the Slack App configuration page, choose the app you’re working on, and go to Features > Interactivity & Shortcuts on the left pane. There are four things to do on the page.

  • Turn on the feature
  • Set the Request URL to https://{your app's public URL domain}/slack/events
  • Add/edit shortcuts in the Shortcuts section
    • Name, Short Description, Callback ID
  • Click the Save Changes button at the bottom for sure

The specified Callback ID will be sent as callback_id in payloads from Slack.

What Your Bolt App Does

All your app needs to do to handle message shortcuts requests are:

  1. Verify requests from Slack
  2. Parse the request body and check if the callback_id is the one you’d like to handle
  3. Build a reply message or do whatever you want to do
  4. Respond to the Slack API server with 200 OK as an acknowledgment

Examples

NOTE: If you’re a beginner to using Bolt for Slack App development, consult Getting Started with Bolt, first.

Bolt does many of the commonly required tasks for you. The steps you need to handle would be:

  • Specify the callback_id to handle (by either of the exact name or regular expression)
  • Build a reply message or do whatever you want to do
  • Call ack() as an acknowledgment

Message shortcut request payloads have response_url, so that your app can reply to the shortcut (even asynchronously after the acknowledgment). The URL is usable up to 5 times within 30 minutes of the shortcut invocation. If you post a message using response_url, call ctx.ack() without arguments and use ctx.respond() to post a message.

Global shortcut request payloads don’t have response_url by default. If you have an input block asking users a channel to post a message, global shortcut request payloads may provide response_urls. To enable this, set the block element type as either channels_select or conversations_select and add "response_url_enabled": true.

Here is a tiny example demonstrating how to handle shortcut requests in a Bolt app.

import com.slack.api.model.Message;
import com.slack.api.model.view.View;
import com.slack.api.methods.response.views.ViewsOpenResponse;

// Handles global shortcut requests
app.globalShortcut("create-task-shortcut-callback-id", (req, ctx) -> {
  // do something with the payload
  ViewsOpenResponse viewsOpenResp = ctx.client().viewsOpen(r -> r
    .triggerId(ctx.getTriggerId())
    .view(buildView()));

  return ctx.ack(); // respond with 200 OK to the request
});

// Handles message shortcut requests (formerly message actions)
app.messageShortcut("create-task-shortcut-callback-id", (req, ctx) -> {
  String userId = req.getPayload().getUser().getId();
  Message message = req.getPayload().getMessage();
  // do something with the message

  ViewsOpenResponse viewsOpenResp = ctx.client().viewsOpen(r -> r
    .triggerId(ctx.getTriggerId())
    .view(buildView(message)));
  if (!viewsOpenResp.isOk()) {
    String errorCode = viewsOpenResp.getError();
    ctx.logger.error("Failed to open a modal view for user: {} - error: {}", userId, errorCode);
    ctx.respond(":x: Failed to open a modal view because of " + errorCode);
  }

  return ctx.ack(); // respond with 200 OK to the request
});

View buildView(Message message) { return null; }
View buildView() { return null; }

The followings are the ones written in Kotlin. (New to Kotlin? Getting Started in Kotlin may be helpful)

// Handles global shortcut requests
app.globalShortcut("create-task-shortcut-callback-id") { req, ctx -> 
  // do something with the payload
  val viewsOpenResp = ctx.client().viewsOpen {
    it.triggerId(ctx.triggerId)
      .view(buildView()))
  }

  ctx.ack() // respond with 200 OK to the request
}

// Handles message shortcut requests (formerly message actions)
app.messageShortcut("create-task-shortcut-callback-id") { req, ctx ->
  val userId = req.payload.user.id
  val message = req.payload.message
  // do something with the message

  val viewsOpenResp = ctx.client().viewsOpen {
    it.triggerId(ctx.triggerId)
      .view(buildView(message))
  }
  if (!viewsOpenResp.isOk) {
    val errorCode = viewsOpenResp.error
    ctx.logger.error("Failed to open a modal view for user: ${userId} - error: ${errorCode}")
    ctx.respond(":x: Failed to open a modal view because of ${errorCode}")
  }

  ctx.ack() // respond with 200 OK to the request
}

Under the Hood

If you hope to understand what is actually happening with the above code, reading the following (a bit pseudo) code may be helpful.

import java.util.Map;
import com.google.gson.Gson;
import com.slack.api.Slack;
import com.slack.api.app_backend.interactive_components.payload.MessageShortcutPayload;
import com.slack.api.util.json.GsonFactory;

PseudoHttpResponse handle(PseudoHttpRequest request) {

  // 1. Verify requests from Slack
  // https://api.slack.com/docs/verifying-requests-from-slack
  // This needs "X-Slack-Signature" header, "X-Slack-Request-Timestamp" header, and raw request body
  if (!PseudoSlackRequestVerifier.isValid(request)) {
    return PseudoHttpResponse.builder().status(401).build();
  }

  // 2. Parse the request body and check if the `callback_id` is the one you'd like to handle

  // payload={URL-encoded JSON} in the request body
  String payloadString = PseudoPayloadExtractor.extract(request.getBodyAsString());
  // The value looks like: { "type": "shortcut", "team": { "id": "T1234567", ... 
  String payloadType = PseudoActionTypeExtractor.extract(payloadString);

  Gson gson = GsonFactory.createSnakeCase();
  if (payloadType.equals("shortcut")) {
    GlobalShortcutPayload payload = gson.fromJson(payloadString, GlobalShortcutPayload.class);
    if (payload.getCallbackId().equals("create-task-shortcut-callback-id")) {
      // 3. Build a reply message or do whatever you want to do
    }
  } else if (payloadType.equals("message_action")) {
    MessageShortcutPayload payload = gson.fromJson(payloadString, MessageShortcutPayload.class);
    if (payload.getCallbackId().equals("create-task-shortcut-callback-id")) {
      // 3. Build a reply message or do whatever you want to do
    }
  } else {
    // other patterns
    return PseudoHttpResponse.builder().status(404).build();
  }

  // 4. Respond to the Slack API server with 200 OK as an acknowledgment
  return PseudoHttpResponse.builder().status(200).build();
}