Listening to events

You can listen to any Events API event using the event() method after subscribing to it in your app configuration. This allows your app to take action when something happens in a workspace where it's installed, like a user reacting to a message or joining a channel.

The event() method requires an eventType of type str.

Refer to the module document to learn the available listener arguments.

# When a user joins the workspace, send a message in a predefined channel asking them to introduce themselves
@app.event("team_join")
def ask_for_introduction(event, say):
    welcome_channel_id = "C12345"
    user_id = event["user"]
    text = f"Welcome to the team, <@{user_id}>! 🎉 You can introduce yourself in this channel."
    say(text=text, channel=welcome_channel_id)

Filtering on message subtypes

The message() listener is equivalent to event("message").

You can filter on subtypes of events by passing in the additional key subtype. Common message subtypes like bot_message and message_replied can be found on the message event page. You can explicitly filter for events without a subtype by explicitly setting None.

# Matches all modified messages
@app.event({
    "type": "message",
    "subtype": "message_changed"
})
def log_message_change(logger, event):
    user, text = event["user"], event["text"]
    logger.info(f"The user {user} changed the message to {text}")