Working with the ConvertKit API

convertkit_features.rb

class ConvertkitFeatures
  TAG_ID = 0000000 # redacted
  
  FORM_ID = 0000000 # redacted
  
  def api_secret = ENV.fetch("CONVERTKIT_API")

  def conn
    @conn ||= Faraday.new("https://api.convertkit.com/v3") do |f|
      f.request :json
      f.response :json
      f.params = { api_secret: }
    end
  end

  def find_subscriber(email_address)
    conn.get("subscribers", { email_address: })
  end

  def tag_subscriber(email)
    conn.post("tags/#{TAG_ID}/subscribe", { email: })
  end

  def new_subscriber(email, first_name)
    # NOTE: this will trigger an opt-in confirmation email!
    conn.post("forms/#{FORM_ID}/subscribe", {
      email:,
      first_name:,
      tags: [TAG_ID]
    })
  end

  def tag_or_subscribe_user(user)
    user.attributes.with_indifferent_access => { email:, first_name: }

    if find_subscriber(email).body["total_subscribers"] > 0
      # already subscribed! go ahead and tag:
      tag_subscriber email
    else
      # it's a new subscriber:
      new_subscriber email, first_name
    end
  end
end

Documentation: https://developers.convertkit.com