Block / Class / Factory / Function processing

block.rb

require 'nokogiri'
require 'uri'
require 'net/http'
require 'byebug'
require 'json'

# Block example
def requester(url, &block)
  uri = URI(url)
  res = Net::HTTP.get_response(uri)

  return unless res.is_a?(Net::HTTPSuccess)

  puts "\n\nProduct title: #{block.call(res)}"
end

requester("https://www.lipsum.com/feed/html") do |result|
  result
    .then { |http| Nokogiri::HTML(http.body) }
    .then { |doc| doc.at("#lipsum").content }
    .then { |text| text.split(".").first }
end

requester("https://dummyjson.com/products/1") do |result|
  result
    .then { |http| JSON.parse(http.body) }
    .then { |json| json.dig("title") }
end

requester("https://cdn.searchspring.net/help/feeds/searchspring.xml") do |result|
  result
    .then { |http| Nokogiri::XML(http.body) }
    .then { |doc| doc.xpath("//Name").children.first.text }
end

# Simple Class
class Requester
  attr_reader :url, :type

  def initialize(url, type)
    @url = url
    @type = type
  end

  def perform
    return unless understood_type?

    puts "\n\nProduct title: #{send(type.to_sym)}"
  end

  protected

  def json
    request
      .then { |http| JSON.parse(http.body) }
      .then { |json| json.dig("title") }
  end

  def html
    request
      .then { |http| Nokogiri::HTML(http.body) }
      .then { |doc| doc.at("#lipsum").content }
      .then { |text| text.split(".").first }
  end

  def xml
    request
      .then { |http| Nokogiri::XML(http.body) }
      .then { |doc| doc.xpath("//Name").children.first.text }
  end

  private

  def understood_type?
    [:xml, :json, :html].include?(type.to_sym)
  end

  def request
    uri = URI(url)
    res = Net::HTTP.get_response(uri)

    return unless res.is_a?(Net::HTTPSuccess)

    res
  end
end

puts Requester.new("https://cdn.searchspring.net/help/feeds/searchspring.xml", :xml).perform
puts Requester.new("https://www.lipsum.com/feed/html", :html).perform
puts Requester.new("https://dummyjson.com/products/1", :json).perform

Class Factory example
class RequesterFactory
  attr_reader :type

  def initialize(type)
    @type = type
  end

  def perform
    requester = case type.to_sym
                when :xml
                  XmlRequester
                when :json
                  JsonRequester
                when :html
                  HtmlRequester
                end

    puts "\n\nProduct title: #{requester.new.perform}"
  end
end

class BaseRequester
  def perform
    raise NotImplementedError
  end

  protected

  def make_request(url)
    uri = URI(url)
    res = Net::HTTP.get_response(uri)

    return unless res.is_a?(Net::HTTPSuccess)

    res
  end
end

class XmlRequester < BaseRequester
  URL = "https://cdn.searchspring.net/help/feeds/searchspring.xml"

  def perform
    make_request(URL)
      .then { |http| Nokogiri::XML(http.body) }
      .then { |doc| doc.xpath("//Name").children.first.text }
  end
end


class JsonRequester < BaseRequester
  URL = "https://dummyjson.com/products/1"

  def perform
    make_request(URL)
      .then { |http| JSON.parse(http.body) }
      .then { |json| json.dig("title") }
  end
end

class HtmlRequester < BaseRequester
  URL = "https://www.lipsum.com/feed/html"

  def perform
    make_request(URL)
      .then { |http| Nokogiri::HTML(http.body) }
      .then { |doc| doc.at("#lipsum").content }
      .then { |text| text.split(".").first }
  end
end

puts RequesterFactory.new(:xml).perform
puts RequesterFactory.new(:html).perform
puts RequesterFactory.new(:json).perform

Bad example
def request_html
  uri = URI("https://www.lipsum.com/feed/html")
  res = Net::HTTP.get_response(uri)

  return unless res.is_a?(Net::HTTPSuccess)

  product_title = res
    .then { |http| Nokogiri::HTML(http.body) }
    .then { |doc| doc.at("#lipsum").content }
    .then { |text| text.split(".").first }

  puts "\n\nProduct title: #{product_title}"
end

def request_xml
  uri = URI("https://cdn.searchspring.net/help/feeds/searchspring.xml")
  res = Net::HTTP.get_response(uri)

  return unless res.is_a?(Net::HTTPSuccess)

  product_title = res
    .then { |http| Nokogiri::XML(http.body) }
    .then { |doc| doc.xpath("//Name") }
    .then { |nodes| nodes.first.text }

  puts "\n\nProduct title: #{product_title}"
end

request_xml
request_html