Add Elasticsearch with elasticsearch-rails

Gemfile

@@ -7,6 +7,8 @@ gem "rails", github: "rails/rails", branch: "main"
 
 gem "bootsnap", require: false
 gem "dotenv-rails"
+gem "elasticsearch-model"
+gem "elasticsearch-rails"
 gem "importmap-rails"
 gem "opengraph_parser"
 gem "pg"

Gemfile.lock

@@ -111,9 +111,46 @@ GEM
     dotenv-rails (2.8.1)
       dotenv (= 2.8.1)
       railties (>= 3.2)
+    elasticsearch (7.17.7)
+      elasticsearch-api (= 7.17.7)
+      elasticsearch-transport (= 7.17.7)
+    elasticsearch-api (7.17.7)
+      multi_json
+    elasticsearch-model (7.2.1)
+      activesupport (> 3)
+      elasticsearch (~> 7)
+      hashie
+    elasticsearch-rails (7.2.1)
+    elasticsearch-transport (7.17.7)
+      faraday (~> 1)
+      multi_json
     erubi (1.12.0)
+    faraday (1.10.3)
+      faraday-em_http (~> 1.0)
+      faraday-em_synchrony (~> 1.0)
+      faraday-excon (~> 1.1)
+      faraday-httpclient (~> 1.0)
+      faraday-multipart (~> 1.0)
+      faraday-net_http (~> 1.0)
+      faraday-net_http_persistent (~> 1.0)
+      faraday-patron (~> 1.0)
+      faraday-rack (~> 1.0)
+      faraday-retry (~> 1.0)
+      ruby2_keywords (>= 0.0.4)
+    faraday-em_http (1.0.0)
+    faraday-em_synchrony (1.0.0)
+    faraday-excon (1.1.0)
+    faraday-httpclient (1.0.1)
+    faraday-multipart (1.0.4)
+      multipart-post (~> 2)
+    faraday-net_http (1.0.1)
+    faraday-net_http_persistent (1.2.0)
+    faraday-patron (1.0.0)
+    faraday-rack (1.0.0)
+    faraday-retry (1.0.3)
     globalid (1.1.0)
       activesupport (>= 5.0)
+    hashie (5.0.0)
     i18n (1.12.0)
       concurrent-ruby (~> 1.0)
     importmap-rails (1.1.5)
@@ -134,6 +171,8 @@ GEM
     mini_mime (1.1.2)
     minitest (5.18.0)
     msgpack (1.7.0)
+    multi_json (1.15.0)
+    multipart-post (2.3.0)
     net-imap (0.3.4)
       date
       net-protocol
@@ -183,6 +222,7 @@ GEM
       connection_pool
     reline (0.3.3)
       io-console (~> 0.5)
+    ruby2_keywords (0.0.5)
     sidekiq (7.0.7)
       concurrent-ruby (< 2)
       connection_pool (>= 2.3.0)
@@ -217,6 +257,8 @@ PLATFORMS
 DEPENDENCIES
   bootsnap
   dotenv-rails
+  elasticsearch-model
+  elasticsearch-rails
   importmap-rails
   opengraph_parser
   pg

app/controllers/search_controller.rb

@@ -0,0 +1,5 @@
+class SearchController < ApplicationController
+  def index
+    @results = Searchable.search(params[:query])
+  end
+end

app/jobs/indexer_job.rb

@@ -0,0 +1,25 @@
+class IndexerJob < ApplicationJob
+  def perform(operation, klass, id)
+    klass = klass.constantize
+
+    case operation
+    when "create"
+      model = klass.find_by_id(id)
+      return unless model
+
+      model.__elasticsearch__.index_document
+    when /update/
+      model = klass.find_by_id(id)
+      return unless model
+
+      model.__elasticsearch__.update_document
+    when /delete/
+      begin
+        klass.__elasticsearch__.client.delete(index: klass.index_name, id: id)
+      rescue Elasticsearch::Transport::Transport::Errors::NotFound # rubocop:disable Lint/SuppressedException
+      end
+    else
+      raise ArgumentError, "Unknown operation '#{operation}'"
+    end
+  end
+end

app/models/concerns/searchable.rb

@@ -0,0 +1,70 @@
+# Description:
+# Include this module in models that should be searchable.
+#
+# Models including the concern are expected to implement 'title' and 'searchable_content'
+# for indexing. Title will be given higher priority compared to content.
+#
+# After adding and indexing your models. Search across all models can be performed via
+# the Searchable.search method.
+
+module Searchable
+  extend ActiveSupport::Concern
+
+  mattr_accessor :models
+  self.models = []
+
+  def self.search(query)
+    return [] if query.blank?
+
+    search_definition = {
+      query: {
+        multi_match: {
+          query: query,
+          fields: ["title^2", "content"],
+        },
+      },
+    }
+
+    Elasticsearch::Model.search(search_definition, models).records
+  end
+
+  def as_indexed_json(_options = {})
+    {
+      title: title,
+      content: searchable_content,
+    }
+  end
+
+  def should_index?
+    true
+  end
+
+  def searchable_content
+    raise NotImplementedError
+  end
+
+  included do
+    include Elasticsearch::Model
+
+    Searchable.models << self
+
+    after_commit on: :create, if: :should_index? do
+      IndexerJob.perform_later("create", self.class.name, id)
+    end
+
+    after_commit on: :update, if: :should_index? do
+      IndexerJob.perform_later("update", self.class.name, id)
+    end
+
+    after_commit on: :destroy do
+      IndexerJob.perform_later("delete", self.class.name, id)
+    end
+
+    settings index: { number_of_shards: 1 } do
+      mappings dynamic: "false" do
+        indexes :title, analyzer: "english", boost: 2
+        indexes :content, analyzer: "english"
+      end
+    end
+  end
+end

app/models/link.rb

@@ -1,4 +1,6 @@
 class Link < ApplicationRecord
+  include Searchable
+
   validates_presence_of :url
   validate :validate_format_of_url
   validates_inclusion_of :state, in: %w[pending success error]
@@ -8,6 +10,14 @@ class Link < ApplicationRecord
 
   private
 
+  def should_index?
+    status == "success"
+  end
+
+  def searchable_content
+    description
+  end
+
   def enqueue_crawl_job
     CrawlLinkJob.perform_later(id)
   end

app/models/post.rb

@@ -1,4 +1,12 @@
 class Post < ApplicationRecord
+  include Searchable
+
   validates_presence_of :title
   validates_presence_of :body
+
+  private
+
+  def searchable_content
+    body
+  end
 end

app/views/layouts/application.html.erb

@@ -14,6 +14,7 @@
     <nav style="font-size: 1.5rem;">
       <%= link_to "Posts", posts_path %>
       <%= link_to "Links", links_path %>
+      <%= link_to "Search", search_path %>
     </nav>
     <%= yield %>
   </body>

app/views/search/index.html.erb

@@ -0,0 +1,16 @@
+<h1>Search</h1>
+
+<%= form_with url: search_path, method: :get do |form| %>
+  <%= form.label :query %>
+  <%= form.text_field :query, value: params[:query], autofocus: true %>
+  <%= form.submit "Search" %>
+<% end %>
+
+<% if @results.present? %>
+  <h2>Results</h2>
+  <ul>
+    <% @results.each do |result| %>
+      <li><%= link_to result.title, result %></li>
+    <% end %>
+  </ul>
+<% end %>

config/environments/development.rb

@@ -9,7 +9,7 @@
   config.enable_reloading = true
 
   # Do not eager load code on boot.
-  config.eager_load = false
+  config.eager_load = true # necessary for inclusion tracking of Searchable concern
 
   # Show full error reports.
   config.consider_all_requests_local = true

config/environments/test.rb

@@ -15,7 +15,7 @@
   # this is usually not necessary, and can slow down your test suite. However, it's
   # recommended that you enable it in continuous integration systems to ensure eager
   # loading is working properly before deploying your code.
-  config.eager_load = ENV["CI"].present?
+  config.eager_load = true # necessary for inclusion tracking of Searchable concern
 
   # Configure public file server for tests with Cache-Control for performance.
   config.public_file_server.enabled = true

config/initializers/elasticsearch.rb

@@ -0,0 +1,8 @@
+# https://github.com/elastic/elasticsearch-ruby/issues/1429#issuecomment-958162468
+module Elasticsearch
+  class Client
+    def verify_with_version_or_header(*_args)
+      @verified = true
+    end
+  end
+end

config/routes.rb

@@ -1,7 +1,8 @@
 Rails.application.routes.draw do
   resources :links
   resources :posts
-  # Define your application routes per the DSL in https://guides.rubyonrails.org/routing.html
+
+  get "search" => "search#index", as: :search
 
   # Reveal health status on /up that returns 200 if the app boots with no exceptions, otherwise 500.
   # Can be used by load balancers and uptime monitors to verify that the app is live.