If we are using PostgreSQL RDBMS in rails application and there are need to search functionality, pg_search gem is perfect for that. It has easy implementation and having rich methods for the search functionality.

Note: pg_search gem supports only PostgreSQL RDBMS

The pg_search provides two different searching criteria in the application

Search Scopes: It is basically used in developing functionality like autocompleters and searching records from lists.

Multi Search: In multi search, an application uses the one global search index approach.

Here we will search results from the articles list against the article title & article content.

Step1: Add pg_search gem in Gemfile

Step2: Run bundler

Step3: Add search field in article index page

Step4: Include pg_search module in model

Step5: Create Scope for search

Step6: Invoke in article_controller

Step1: Add pg_search gem in Gemfile

Path: my_app/Gemfile

gem 'pg_search'

Step2: Run bundler

Now run bundler using command

bundle install

Step3: Add search field in article index page

In index.html.erb we add the search form bu which user can search articles.

Path: my_app/app/views/articles/index.html.erb

<%= form_tag(artiles_index_path, method: "get") do %>
  <%= label_tag(:query, "Search for:") %>
  <%= text_field_tag(:query) %>
  <%= submit_tag("Search") %>
<% end %>

<table>
  <tr>
    <th>Title</th>
    <th>Content</th>
  </tr>
  <% @articles.each do |article| %>
    <tr>
      <td><%= article.title %></td>
      <td><%= article.content %></td>
    </tr>
  <% end %>
</table>

Step4: Include pg_search module in model

Then modify article.rb model like below:

Path: my_app/app/models/article.rb

class Article < ActiveRecord::Base
	include PgSearch
 	pg_search_scope :search_title, :against => [:title, :content]
end

'include PgSearch ' this line include the pgSerach module into article model

' pg_search_scope' this is defined scope name i.e 'search_title' and  ' against' used to set the table columns for the search

Step6: Invoke scope in article_controller

Here we will call the scope for searching in controller

Path: my_app/app/controllers/articles_controller.rb

class ArticlesController < ApplicationController

  def index
      if params[:query].present?
          @articles = Article.search_title(params[:query])
      else
          @articles = Article.all
      end
   end
end

In the above code, first we checked the search query string, if present, then called the search scope to get records otherwise it will go into else condition. We will discuss other searching features of pg_search gem in next blog.