Exercise using the NationBuilder Events API

nation_builder_events.rb

#
# This is very rudimentary web app that allows you to create and update
# an Event record using the NationBuilder API. This covers just the
# basics - many details have been left out.
#
# The app was built in Ruby 2.2.0, using the Sinatra web framework, and the
# NationBuilder API Ruby gem.
#
# To run the app:
#   * gem install sinatra
#   * gem install nationbuilder-rb
#   * set environment variables NB_SLUG and NB_API_KEY to your NationBuilder slug and
#     API key respectively
#   * ruby nation_builder_events.rb
#   * point your browser to http://localhost:4567/people
#
require "sinatra"
require "nationbuilder"

# This class wraps the NationBuilder API gem, exposing an Event-centric interface
class NBClient

  class << self

    def create_event(event_params)
      format_datetimes!(event_params)
      execute_call do
        client.call(:events, :create, site_slug: ENV["NB_SLUG"], event: event_params)["event"]
      end
    end

    def fetch_event(id)
      event = {}
      execute_call do
        event = client.call(:events, :show, site_slug: ENV["NB_SLUG"], id: id)["event"]
      end
      event.tap { format_datetimes!(event) }
    end

    def update_event(event_params)
      format_datetimes!(event_params)
      execute_call do
        client.call(:events, :update, site_slug: ENV["NB_SLUG"], id: event_params["id"],
          event: event_params)["event"]
      end
    end

    private

    def client
      @client ||= NationBuilder::Client.new(ENV["NB_SLUG"], ENV["NB_API_KEY"], retries: 8)
    end

    def execute_call
      result = {}
      error = nil
      begin
        result = yield
      rescue Exception => e
        error = e.to_s
      end
      [result, error]
    end

    # convert date/time strings to and from form inputs; using UTC for the sake of brevity
    def format_datetimes!(event)
      if event.has_key?("start")
        event["start_time"] = format_datetime(event["date"], event["start"])
        event["end_time"] = format_datetime(event["date"], event["end"])
      elsif event.has_key?("start_time")
        start_time = DateTime.parse(event["start_time"]).to_time.utc()
        end_time = DateTime.parse(event["end_time"]).to_time.utc()
        event["date"] = start_time.strftime("%m/%d/%Y")
        event["start"] = start_time.strftime("%H:%M")
        event["end"] = end_time.strftime("%H:%M")
      end
    end

    # again, for the sake of brevity, we're just assuming the input is clean; normally,
    # you'd want to do a lot more sanity checking here
    def format_datetime(date_str, time_str)
      (month,date,year) = date_str.split("/")
      (hour, minute) = time_str.split(":")
      Time.new(year, month, date, hour, minute, 0, 0).strftime("%FT%T%:z")
    end
  end

end

###################################
# Web app pages

# displays an empty form for creating an Event
get "/events" do
  html = <<-END_HTML
    #{show_form(event: {})}
  END_HTML
end

# uses the form data to create an Event in NationBuilder and display the results
post "/events/create" do
  (result, error) = NBClient.create_event(params)
  if error
    show_form(event: result, error: error)
  else
    redirect to("/events/edit/#{result["id"]}?message=Created")
  end
end

# displays the current Event record in an editable form
get "/events/edit/:id" do
  (result, error) = NBClient.fetch_event(params[:id])
  html = <<-END_HTML
    #{show_form(event: result, error: error)}
  END_HTML
end

# handles updating the Event record in NationBuilder
post "/events/update/:id" do
  (result, error) = NBClient.update_event(request.params)
  if error
    show_form(event: result, error: error)
  else
    redirect to("/events/edit/#{result["id"]}?message=Updated")
  end
end

private

# the main UI
def show_form(event: {}, error: "")
  new_record = event["id"].nil?
  method = new_record ? "/events/create" : "/events/update/#{event["id"]}"
  form = <<-END_HTML
    <form action="#{method}" method="post">
      <p>#{params[:message]}</p>
      <p>#{error}</p>
      <table>
        <tr>
          <td>Event name:</td>
          <td><input type="text" name="name" value="#{event["name"]}"></td>
        </tr>
        <tr>
          <td>Headline:</td>
          <td><input type="text" name="headline" value="#{event["headline"]}"></td>
        </tr>
        <tr>
          <td>Date (mm/dd/yyyy):</td>
          <td><input type="text" name="date" value="#{event["date"]}"></td>
        </tr>
        <tr>
          <td>Start time (hh:mm):</td>
          <td><input type="text" name="start" value="#{event["start"]}"></td>
        </tr>
        <tr>
          <td>End time (hh:mm):</td>
          <td><input type="text" name="end" value="#{event["end"]}"></td>
        </tr>
        <tr>
          <td>Status:</td>
          <td>
            <select name="status">
              #{status_options(event)}
            </select>
          </td>
        </tr>
      </table>
      <input type="hidden" name="id" value="#{event["id"]}">
      <input type="submit" value="#{new_record ? "Create" : "Update"}">
    </form>
  END_HTML
end

def status_options(event)
  ["published", "unlisted", "hidden"].map do |status|
    "<option #{event["status"] == status ? "selected" : ""}>#{status}</option>"
  end.join("\n")
end