active_record_associations.rb

# An example of elasticsearch & Tire setup for ActiveRecord associations.
#
# A `Book has_many :chapters` scenario, with mapping and JSON serialization
# for indexing associated models.
#
# Demonstrates three important caveats as of now:
#
# 1. You you have to use `touch: true` in the `belongs_to` declaration,
#    to automatically notify the parent model about the update.
#
# 2. You have to explicitely hook up updating elasticsearch index via
#    the `after_touch` callback in the parent model.
#
# 3. You have to disable `include_root_in_json` for proper JSON serialization.
#
#
# Run me with:
#
#     $ ruby active_record_associations.rb 
#

require 'logger'
require 'ansi/core'
require 'active_record'
require 'oj'
require 'tire'

def _(message=nil); puts '-'*80, ANSI.bold(message.to_s), '-'*80; end

ActiveRecord::Base.logger = Logger.new(STDERR)
ActiveRecord::Base.establish_connection( adapter: 'sqlite3', database: ":memory:" )

Tire.configure { logger STDERR }

_ "Creating ActiveRecord schema..."

ActiveRecord::Schema.define(version: 1) do
  create_table :books do |t|
    t.string   :title
    t.timestamps
  end
  create_table :chapters do |t|
    t.string   :text
    t.integer  :number, :book_id
    t.timestamps
  end
  add_index(:chapters, :book_id)
end

_ "Deleting elasticsearch index..."

Tire.index('books').delete

# The Book class
#
class Book < ActiveRecord::Base
  has_many :chapters

  # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
  # Enable automatic saving in elasticsearch when associated objects change
  #
  after_touch() { tire.update_index }
  #
  # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

  # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
  # Properly serialize JSON for elasticsearch
  #
  self.include_root_in_json = false
  # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

  include Tire::Model::Search
  include Tire::Model::Callbacks

  # Define the mapping
  #
  mapping do
    indexes :title,      type: 'string', boost: 10, analyzer: 'snowball'
    indexes :created_at, type: 'date'

    indexes :chapters do
      indexes :text, analyzer: 'snowball'
    end
  end

  # Define the JSON serialization
  #
  def to_indexed_json
    to_json( include: { chapters: { only: [:text] } } )
  end

end

# The book Chapter class
#
class Chapter < ActiveRecord::Base
  # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
  # Do not forget to automatically `touch` parent object from associations
  belongs_to :book, touch: true
  # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
end

_ "Create book instance..."

book = Book.create   title: "How to impress your Rails friends with elasticsearch"
book.chapters.create number: 1, text: "The world generates more and more information ..."
book.chapters.create number: 2, text: "After the elasticsearch installation ..."

p Book.first
p Book.first.chapters

_ "Refresh the index for immediate search (there's a 1 second delay by default)..."

Book.tire.index.refresh

_ "Search 'elasticsearch' in book titles..."

results = Book.search('title:elasticsearch')

puts ANSI.green( "Found: '%s'" % results.first.title )

_ "Search 'install' in chapter text..."

results = Book.search('chapters.text:install')

puts ANSI.green( "Found: '%s'" % results.first.title )

_ "Search 'elasticsearch' anywhere with highlighting..."

results = Book.search do
  query { string "elasticsearch" }
  highlight 'title', 'chapters.text'
end

puts ANSI.green( "Found: '%s'" % results.first.title ),
     '-'*80,
     "Highlights: ",
     results.first.highlight.to_hash              \
      .map { |k,v| '  - ' + k.to_s + ": " + v.first.to_s } \
      .map { |s|   s.gsub(/<em>([^<]+)<\/em>/, ANSI.yellow + ANSI.bold + '\1' + ANSI.reset) } \
      .join("\n")