Slack real time messaging and web API client in Elixir
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Latest commit 4812cf8 Oct 14, 2018

README.md

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Elixir-Slack

This is a Slack Real Time Messaging API client for Elixir. You'll need a Slack API token which can be retrieved from the Web API page or by creating a new bot integration.

Installing

Add Slack to your mix.exs dependencies function.

def application do
  [extra_applications: [:logger]]
end

def deps do
  [{:slack, "~> 0.14.0"}]
end

RTM (Bot) Usage

Define a module that uses the Slack behaviour and defines the appropriate callback methods.

defmodule SlackRtm do
  use Slack

  def handle_connect(slack, state) do
    IO.puts "Connected as #{slack.me.name}"
    {:ok, state}
  end

  def handle_event(message = %{type: "message"}, slack, state) do
    send_message("I got a message!", message.channel, slack)
    {:ok, state}
  end
  def handle_event(_, _, state), do: {:ok, state}

  def handle_info({:message, text, channel}, slack, state) do
    IO.puts "Sending your message, captain!"

    send_message(text, channel, slack)

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

To run this example, you'll want to call Slack.Bot.start_link(SlackRtm, [], "TOKEN_HERE") and run the project with mix run --no-halt.

You can send messages to channels using send_message/3 which takes the message as the first argument, channel/user as the second, and the passed in slack state as the third.

The passed in slack state holds the current user properties as me, team properties as team, the current websocket connection as socket, and a list of bots, channels, groups, users, and ims (direct message channels).

If you want to do things like trigger the sending of messages outside of your Slack handlers, you can leverage the handle_info/3 callback to implement an external API.

This allows you to both respond to Slack RTM events and programmatically control your bot from external events.

{:ok, rtm} = Slack.Bot.start_link(SlackRtm, [], "token")
send rtm, {:message, "External message", "#general"}
#=> {:message, "External message", "#general"}
#==> Sending your message, captain!

Slack has a lot of message types so it's a good idea to define a callback like above where unhandled message types don't crash your application. You can find a list of message types and examples on the RTM API page.

You can find more detailed documentation on the Slack hexdocs page.

Web API Usage

The complete Slack Web API is implemented by generating modules/functions from the JSON documentation. You can view this project's documentation for more details.

There are two ways to authenticate your API calls. You can configure api_token on slack that will authenticate all calls to the API automatically.

config :slack, api_token: "VALUE"

Alternatively you can pass in %{token: "VALUE"} to any API call in optional_params. This also allows you to override the configured api_token value if desired.

Quick example, getting the names of everyone on your team:

names = Slack.Web.Users.list(%{token: "TOKEN_HERE"})
|> Map.get("members")
|> Enum.map(fn(member) ->
  member["real_name"]
end)

Web Client Configuration

A custom client callback module can be configured for cases in which you need extra control over how calls to the web API are performed. This can be used to control timeouts, or to add additional custom error handling as needed.

config :slack, :web_http_client, YourApp.CustomClient

All Web API calls from documentation-generated modules/functions will call post!/2 with the generated url and body passed as arguments.

In the case where you only need to control the options passed to HTTPoison/hackney, the default client accepts a keyword list as an additional configuration parameter. Note that this is ignored if configuring a custom client.

See HTTPoison docs for a list of avilable options.

config :slack, :web_http_client_opts, [timeout: 10_000, recv_timeout: 10_000]

Testing

For integration tests, you can change the default Slack URL to your fake Slack server:

config :slack, url: "http://localhost:8000"