index.html.erb

<div class="container">
  <%= form_tag movies_path, method: :get do %>
    <%= text_field_tag :query,
      params[:query],
      class: "form-control",
      placeholder: "Find a movie"
    %>
    <%= submit_tag "Search", class: "btn btn-primary" %>
  <% end %>

  <div class="row">
    <div class="col-sm-8 offset-sm-2">
      <div id="movies" class="mt-4">
        <% @movies.each do |movie| %>
          <h4><%= movie.title %></h4>
          <p><%= movie.syllabus %></p>
        <% end %>
      </div>
    </div>
  </div>
</div>

movie.rb

class Movie < ApplicationRecord
  belongs_to :director
  include PgSearch::Model
  multisearchable against: [:title, :syllabus]

  scope :with_directors, ->(query){
    sql_query = " \
        movies.title @@ :query \
        OR movies.syllabus @@ :query \
        OR directors.first_name @@ :query \
        OR directors.last_name @@ :query \
      "
    joins(:director).where(sql_query, query: "%#{query}%")
  }

  pg_search_scope :search_by_title_and_syllabus,
    against: [ :title, :syllabus ],
    using: {
      tsearch: { prefix: true } # <-- now `superman batm` will return something!
    }

  pg_search_scope :global_search,
    against: [ :title, :syllabus ],
    associated_against: {
      director: [ :first_name, :last_name ]
    },
    using: {
      tsearch: { prefix: true }
    }
end

movies_controller.rb

class MoviesController < ApplicationController

  def index
    if params[:query].present?
      @movies = Movie.with_directors(params[:query])
    else
      @movies = Movie.all
    end
  end

  # def index
  #   if params[:query].present?
  #     sql_query = " \
  #       movies.title @@ :query \
  #       OR movies.syllabus @@ :query \
  #       OR directors.first_name @@ :query \
  #       OR directors.last_name @@ :query \
  #     "
  #     @movies = Movie.joins(:director).where(sql_query, query: "%#{params[:query]}%")
  #   else
  #     @movies = Movie.all
  #   end
  # end

  # def index
  #   if params[:query].present?
  #     sql_query = " \
  #       movies.title ILIKE :query \
  #       OR movies.syllabus ILIKE :query \
  #       OR directors.first_name ILIKE :query \
  #       OR directors.last_name ILIKE :query \
  #     "
  #     @movies = Movie.joins(:director).where(sql_query, query: "%#{params[:query]}%")
  #   else
  #     @movies = Movie.all
  #   end
  # end

  # def index
  #   if params[:query].present?
  #     sql_query = "title ILIKE :query OR syllabus ILIKE :query"
  #     @movies = Movie.where(sql_query, query: "%#{params[:query]}%")
  #   else
  #     @movies = Movie.all
  #   end
  # end

  # def index
  #   if params[:query].present?
  #     @movies = Movie.where("title ILIKE ?", "%#{params[:query]}%")
  #   else
  #     @movies = Movie.all
  #   end
  # end


  # def index
  #   if params[:query].present? # In a form, user typed "Batman"
  #     @movies = Movie.where(title: params[:query]) # params[:query] => "Batman"
  #   else
  #     @movies = Movie.all
  #   end
  # end
end

tv_show.rb

class TvShow < ApplicationRecord
  include PgSearch::Model
  multisearchable against: [:title, :syllabus]
end