Emoji & Reactions

ChatSDK provides a unified API for adding and removing emoji reactions, and for handling reaction events from users.

Adding Reactions

Use thread.react to add an emoji reaction to a message:

bot.on_new_mention do |thread, message|
  # Add an "eyes" reaction to acknowledge receipt
  thread.react(message.id, "eyes")

  # Do work...
  result = process_request(message.text)

  # Replace with a checkmark when done
  thread.unreact(message.id, "eyes")
  thread.react(message.id, "white_check_mark")
  thread.post(result)
end

Emoji names are platform-specific shortcodes (e.g., "thumbsup", "rocket", "white_check_mark"). On Google Chat, unicode emoji characters are used.

Removing Reactions

thread.unreact(message.id, "eyes")

Handling Reaction Events

bot.on_reaction do |event|
  if event.added?
    puts "#{event.user_id} added :#{event.emoji}: to #{event.message_id}"
  else
    puts "#{event.user_id} removed :#{event.emoji}: from #{event.message_id}"
  end
end

Filtering by Emoji

Pass an array of emoji names to filter:

bot.on_reaction(%w[thumbsup thumbsdown]) do |event|
  if event.emoji == "thumbsup"
    event.thread.post("Thanks for the upvote!")
  else
    event.thread.post("Sorry to hear that.")
  end
end

Only events with matching emoji will trigger the handler. Unmatched reactions are ignored.

The Reaction Event

Attribute	Type	Description
`emoji`	`String`	Emoji name (e.g., `"thumbsup"`)
`user_id`	`String`	Who reacted
`message_id`	`String`	The message that was reacted to
`thread_id`	`String`	Thread identifier
`channel_id`	`String`	Channel identifier
`added?`	`Boolean`	`true` if the reaction was added
`removed?`	`Boolean`	`true` if the reaction was removed
`thread`	`Thread`	For posting replies
`platform`	`Symbol`	Which platform

Platform Support

Platform	Add Reaction	Remove Reaction	Inbound Events
Slack	Yes	Yes	Yes
Teams	No (declared but raises PlatformError)	No	Yes
Google Chat	Yes (unicode)	Yes	Yes

Teams declares the :reactions capability because it parses inbound reaction events, but the Bot Framework API does not support programmatically adding or removing reactions.

Common Patterns

Reaction-Based Voting

bot.on_reaction(%w[thumbsup thumbsdown]) do |event|
  return unless event.added?

  # Track votes in thread state
  votes = event.thread.state || { "up" => 0, "down" => 0 }
  key = event.emoji == "thumbsup" ? "up" : "down"
  votes[key] += 1
  event.thread.set_state(votes)

  event.thread.post("Votes: #{votes["up"]} up / #{votes["down"]} down")
end

Reaction as Trigger

bot.on_reaction(%w[rocket]) do |event|
  return unless event.added?
  event.thread.post("Launching deployment...")
end

Testing Reactions

bot = ChatSDK::Testing.build_bot
adapter = bot.config.adapters[:test]

bot.on_reaction do |event|
  event.thread.react(event.message_id, "thumbsup") if event.added?
end

adapter.simulate_reaction(bot, emoji: "wave", added: true)

assert_equal 1, adapter.reactions_added.size
assert_equal "thumbsup", adapter.reactions_added.first.emoji

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