warmup.rb

require 'json'
require 'open-uri'
require 'active_model'
require 'active_support'
require 'active_support/core_ext'

class Market 
  include ActiveModel::Model
  ATTRIBUTES = [:id, :schedule, :address, :google_link]
  
  attr_accessor :id, :schedule, :address, :google_link
end

class MarketGateway
  REMOTE_URL = "http://search.ams.usda.gov/farmersmarkets/v1/data.svc/"
  DEFAULT_LIST_SIZE = 5
  attr_accessor :zip_code, :markets

  def initialize(opts = {})
    self.zip_code = opts[:zip_code]
  end

  def fetch!(opts = {})
    opts[:size] ||= DEFAULT_LIST_SIZE
    market_list = JSON.load open("#{REMOTE_URL}zipSearch?zip=#{zip_code}")
    market_ids = market_list["results"].take(opts[:size]).map { |m| m['id'] }
    self.markets = market_ids.map { |id| fetch_market(id) }
  end

  private

  def fetch_market(id)
    response = JSON.load open("#{REMOTE_URL}mktDetail?id=#{id}")
    market_from_json(response["marketdetails"])
  end

  def market_from_json(json)
    json = json.dup
    json.deep_transform_keys!(&:underscore)
    json.select! { |k, _v| Market::ATTRIBUTES.include? k }
    Market.new(json)
  end
end

markets = MarketGateway.new(zip_code: 11237).fetch!
# TODO: this code executes 6 network requests in serial order, which is guaranteed
# to slow a controller response to a standstill. MarketGateway.fetch! should at least
# fetch the individual markets in parallel with something like Typhoeus.