As web applications grow and accumulate data, providing efficient and fast search functionality becomes increasingly important. Elasticsearch, an open-source search and analytics engine, offers robust full-text search capabilities, scalability, and near real-time search performance. Integrating Elasticsearch with a Ruby on Rails application can significantly enhance your app's search capabilities, making it more responsive and user-friendly. This blog will walk you through the process of integrating Elasticsearch with Rails, implementing search functionality, and optimizing performance for a professional-grade application.

Why Choose Elasticsearch?
Elasticsearch is built on top of Apache Lucene and offers several key advantages:

      i) Speed: Delivers fast search responses even with large datasets.

      ii) Scalability: Easily scales horizontally to handle increased data and load.

      iii) Flexibility: Supports complex queries and full-text search.

      iv) Real-Time Search: Provides near real-time search capabilities

Prerequisites
Before we dive into the integration process, ensure you have the following:

        i) A Rails application (version 6 or higher recommended)

       ii) Basic knowledge of Rails and Ruby

       iii) Elasticsearch installed and running on your local machine or server

​Step 1: Installing Elasticsearch
First, install Elasticsearch on your system. You can find detailed installation instructions for different operating systems on the Elasticsearch official documentation.
For ubantu users, you can install Elasticsearch using the following commands:

 

 wget -qO - https://artifacts.elastic.co/GPG-KEY-elasticsearch | sudo apt-key add - && \
sudo sh -c 'echo "deb https://artifacts.elastic.co/packages/7.x/apt stable main" > /etc/apt/sources.list.d/elastic-7.x.list' && \
sudo apt-get update && \
sudo apt-get install -y elasticsearch && \
sudo systemctl enable elasticsearch && \
sudo systemctl start elasticsearch && \
curl -X GET "localhost:9200/"

Step 2: Adding Elasticsearch Gems to Your Rails Application

To integrate Elasticsearch with Rails, we'll use the elasticsearch-model and elasticsearch-rails gems, which provide easy-to-use integration with Rails.

Add the following gems to your Gemfile:

 

gem 'elasticsearch-model', '~> 8.0'
gem 'elasticsearch-rails', '~> 8.0'

 Run bundle install to install the gems.
Step 3: Setting Up Elasticsearch in Your Rails Application
Let's configure Elasticsearch in a Rails model. For this example, we'll use a Post model.
Generate the Post Model:

Generate the Post Model:
 

rails generate model Post title:string body:text
rails db:migrate

Include Elasticsearch in the Model: 
Open app/models/post.rb and include the Elasticsearch modules:

 

class Post < ApplicationRecord
  include Elasticsearch::Model
  include Elasticsearch::Model::Callbacks
end
# Create the Elasticsearch index for the Post model
Post.__elasticsearch__.create_index!
Post.import

 Step 4: Indexing Data
With Elasticsearch integrated, we need to index our existing data:

rails console
Post.import # This will index all existing Post records

Step 5: Implementing Search Functionality
Now, let's implement a basic search functionality.

1. Add a Search Method to the Model:

 

class Post < ApplicationRecord
  include Elasticsearch::Model
  include Elasticsearch::Model::Callbacks
def self.search(query)
    __elasticsearch__.search(
      {
        query: {
          multi_match: {
            query: query,
            fields: ['title^5', 'body']
          }
        }
      }
    )
  end
end

 2. Create a Search Controller:

 

 rails generate controller Search index

In app/controllers/search_controller.rb:

 class SearchController < ApplicationController
  def index
    if params[:query].present?
      @posts = Post.search(params[:query]).records
    else
      @posts = Post.all
    end
  end
end

 3.Set Up Routes:
In config/routes.rb:

 

 Rails.application.routes.draw do
  get 'search', to: 'search#index'
  resources :posts
end

4.Create the Search View:
In app/views/search/index.html.erb:

 

<h1>Search Results</h1>
<%= form_tag search_path, method: :get do %>
  <%= text_field_tag :query, params[:query] %>
  <%= submit_tag 'Search' %>
<% end %>
<% if @posts.present? %>
  <ul>
    <% @posts.each do |post| %>
      <li><%= link_to post.title, post %></li>
    <% end %>
  </ul>
<% else %>
  <p>No results found</p>
<% end %>

Step 6: Advanced Search Features
Elasticsearch offers powerful querying capabilities. You can refine your search method to include more advanced features like filtering, sorting, and pagination.

Example of Adding Filters and Sorting:

 def self.search(query, options = {})
  search_definition = {
    query: {
      bool: {
        must: [
          {
            multi_match: {
              query: query,
              fields: ['title^5', 'body']
            }
          }
        ],
        filter: options[:filter] || []
      }
    },
    sort: options[:sort] || { _score: { order: 'desc' } }
  }
 __elasticsearch__.search(search_definition)
end

 Step 7: Optimizing Performance
To ensure optimal performance:

      i) Use Aliases: Use index aliases to minimize downtime during reindexing.

      ii) Batch Processing: Index records in batches to avoid memory overload.

     iii) Monitor and Tune: Regularly monitor Elasticsearch performance and tune settings as necessary.

Conclusion
Integrating Elasticsearch with Rails can greatly enhance your application's search capabilities. By following this guide, you can set up and configure Elasticsearch, index your data, and implement robust search functionality in your Rails app. With its powerful features and scalability, Elasticsearch is a valuable tool for any Rails developer looking to provide efficient and effective search capabilities.