slack.cr

Crystal client for building Slack apps and tools using the Slack API.

Installation

  1. Add the dependency to your shard.yml:

    dependencies:
  slack:
    github: the-business-factory/slack.cr

  2. Run shards install

Usage

Demo App

A demo app is published at https://github.com/the-business-factory/hirobot.app.

Configuration

Slack.configure do |config|
  config.bot_scopes = ["incoming-webhook"] # Array(String)
  config.client_id = ENV["SLACK_CLIENT_ID"] # String
  config.client_secret = ENV["SLACK_CLIENT_SECRET"] # String
  config.signing_secret = ENV["SLACK_SIGNING_SECRET"] # String
  config.signing_secret_version = "v0" # String
  config.webhook_delivery_time_limit = 5.minutes # Time::Span
end

# Most apps will want to have OAuth enabled for installation.
Slack::AuthHandler.configure do |config|
  config.oauth_redirect_url = ENV["OAUTH_REDIRECT_URL"]
end

Processing Webhook Events

require "slack"

def process_webhook(request : HTTP::Request)
  event_payload = Slack.process_webhook(event)
  case event_payload
  when .is_a?(Slack::UrlVerification)
    json(event_payload.response.to_json)
  else
    handle_event(event_payload.event)
  end
end

# You can easily handle only the events you expect back, with type safety.
def handle_event(event : Slack::Event::Message::MessageChanged)
  pp event.message.text
end

# And of course sometimes, you just want to ignore things you don't expect.
def handle_event(unhandled_event)
end

Web API calls

class SlackWebhookEvent < WebhookAction
  post "/slack/webhook_events" do
    event_payload = Slack.process_webhook(request)
    case event_payload
    when Slack::UrlVerification
      json(event_payload.response)
    else
      handle_event(event_payload.event)
      json({ok: true})
    end
  end

  def handle_event(message : Slack::Events::Message)
    return unless message.public_channel?

    auth_token = SlackAccessTokenQuery
      .new
      .slack_team_id(message.team)
      .created_at
      .desc_order
      .first

    # channel : Slack::Models::PublicChannel
    channel = Slack::Api::ConversationsInfo.new(token, message.channel_id).call

    # Deal with Slack's polymorphic API in uniform ways.
    case channel
    when Slack::Models::PublicChannel
      Log.info { "Public Team Channel Name: #{channel.name}" }
    end
  end
end

Slack UI Tools

# Users can easily define custom UI components to help build out "app specific"
# "UI Kits" fairly easily, focusing on the UX and business logic rather than
# the stupid internals of Slack's API.
class ButtonSection < Slack::UI::CustomComponent
  include Slack::UI::BaseComponents

  def self.render(action_id : String)
    buttons = %w(Submit Cancel).map do |text|
      style = text == "Submit" ? ButtonStyles::Primary : ButtonStyles::Danger
      ButtonElement.render(
        action_id: "#{action_id}_#{text.downcase}",
        button_text: text,
        style: style
      )
    end

    Slack::UI::Blocks::Actions.new elements: buttons
  end
end

class SlackLinkPage < WebhookAction
  include Slack::UI::BaseComponents

  post "/slack/links" do
    command = Slack.process_command(request)
    text = command.text.presence || "nothing"

    text_section = TextSection.render(
      text: "processed #{command.command} with #{text} as text."
    )

    input_element = InputElement.render(
      action_id: "compensation",
      placeholder_text: "e.g. $120,000-$190,000",
      label_text: "Compensation",
      initial_value: ""
    )

    button_section = ButtonSection.render(
      action_id: "button_group_#{Random::Secure.hex}"
    )

    json({blocks: [text_section, input_element, button_section]})
  end
end

Contributing

  1. Fork it (https://github.com/the-business-factory/slack.cr/fork)
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request

Contributors