Slack is a genserver-ish interface for working with the Slack real time messaging API through a Websocket connection.

To use this module you'll need a need a Slack API token which can be retrieved by following the Token Generation Instructions or by creating a new bot integration.

Example

defmodule Bot do
  use Slack

  def handle_event(message = %{type: "message"}, slack, state) do
    if message.text == "Hi" do
      send_message("Hello to you too!", message.channel, slack)
    end

    {:ok, state}
  end
  def handle_event(_, _, state), do: {:ok, state}
end

Slack.Bot.start_link(Bot, [], "API_TOKEN")

handle_* methods are always passed slack and state arguments. The slack argument holds the state of Slack and is kept up to date automatically.

In this example we're just matching against the message type and checking if the text content is "Hi" and if so, we reply with our own greeting.

The message type is pattern matched against because the Slack RTM API defines many different types of messages that we can receive. Because of this it's wise to write a catch-all handle_event/3 in your bots to prevent crashing.

Callbacks

• handle_connect(slack, state) - called when connected to Slack.
• handle_event(message, slack, state) - called when a message is received.
• handle_close(reason, slack, state) - called when websocket is closed before process is terminated.
• handle_info(message, slack, state) - called when any other message is received in the process mailbox.

Slack argument

The Slack argument that's passed to each callback is what contains all of the state related to Slack including a list of channels, users, groups, bots, and even the socket.

Here's a list of what's stored:

• me - The current bot/users information stored as a map of properties.
• team - The current team's information stored as a map of properties.
• bots - Stored as a map with id's as keys.
• channels - Stored as a map with id's as keys.
• groups - Stored as a map with id's as keys.
• users - Stored as a map with id's as keys.
• ims (direct message channels) - Stored as a map with id's as keys.
• socket - The connection to Slack.
• client - The client that makes calls to Slack.

For all but socket and client, you can see what types of data to expect each of the types to contain from the Slack API types page.