Example of search methods in Postgresql

application_helper.rb

# app/helpers/application_helper.rb
module ApplicationHelper
  # Search form tag, render html form for bootstrap 3
  # params
  #   - path, url of controller action: clients_path
  #   - placeholder text:  'Search by Name or Nickname'
  # Return 
  # HTML safe string
	def search_form(path, placeholder)
		form_tag path, class: "well", :method => 'get' do
			content_tag :div, class: 'row' do
				content_tag :div, class: 'col-md-6' do
					content_tag :div, class: 'input-group' do
						text_field_tag(:finder, params[:finder], :class => "form-control input-sm", :placeholder => placeholder)+
						content_tag(:span, class: 'input-group-btn') do
							submit_tag("Search", :class => 'btn btn-success btn-sm spin')
						end
					end
				end
			end
		end
	end
end

client.rb

# app/models/client.rb
class Client < ActiveRecord::Base
  # Include Searchable concern
  include Searchable
end  
  

clients_controller.rb

# app/controllers/clients_controller.rb
@clients = Client.search(params[:finder], params[:page], ['name', "nickname", "email", "date"])

index.html.erb

<!--app/views/clients/index.html.erb -->
<%= search_form(cients_path, "Search by Name or Nickname" ) %>

searchable.rb

# app/models/concerns/searchable.rb
module Searchable
	extend ActiveSupport::Concern

	module ClassMethods
	
	  # Search method basen in will_paginate gem
	  # params
	  #   - string pattern: "Jhon"
	  #   - integer page: 10
	  #   - array of attribute names as string: ['name', 'email', 'nickname']
	  # Return
	  # Wil paginate records
		def search(pattern, page, attr)
			paginate :per_page 		=> 20, :page => page,
			         :conditions 	=> string_builder(attr, pattern)
		end

		private
		
		# Build string search and params for conditions based in attributes
		# params 
		#   - array of attribute names as strings: ['name', 'email', 'nickname']
		#   - string pattern: "Jhon"
		# Return
		#    ["UPPER(cast(name)), UPPER(cast(email)), UPPER(cast(nickname)) LIKE ? or ? or ?", "%Jhon%", "%Jhon%", "%Jhon%"]
		def string_builder(attr, pattern)
			finder ||= ""
			arr = []
			arr << attr.map{|att| " UPPER(cast(#{att} as text)) LIKE ?"}.join(' or')
			arr << attr.map{|att| '%'+pattern.upcase+'%'}
			arr.flatten
		end
	end
end