dgorodnichy

class FilmRating < ApplicationRecord
  self.primary_key = :id

  def self.refresh
    Scenic.database.refresh_materialized_view(table_name, concurrently: false, cascade: false)
  end
end

dgorodnichy

class CreateFilmRatings < ActiveRecord::Migration[6.0]
  def change
    create_view :film_ratings, materialized: true
  end
end

dgorodnichy

SELECT row_number() OVER () AS id,
AVG(rate) AS rate,
Films.id AS film_id,
Films.title AS title,
Films.genre AS genre
FROM Films
LEFT OUTER JOIN Reviews ON Reviews.film_id=Films.id
GROUP BY Films.id;

dgorodnichy

class FilmsController < ApplicationController
  def index
    @films = serialized_films
    render json: @films
  end

  private

  def films_scope
    Film.all

dgorodnichy

class FilmCarrier
  delegate_missing_to :@film

  def initialize(film, cached_stats: nil)
    @film = film
    @cached_ratings_stats = cached_stats || calculate_stats(film)
  end

  def avg_rating
    @cached_ratings_stats[:avg_ratings][@film.id]

dgorodnichy

class FilmsController < ApplicationController
  def index
    @films = serialized_films
    render json: @films
  end

  private

  def films_scope
    Film.all

dgorodnichy

class FilmsController < ApplicationController
  def index
    @films = serialized_films
    render json: @films
  end

  def serialized_films
    Film.all.map do |film|
      {
        title: film.title,

dgorodnichy

class Medium
  cattr_accessor :source
  self.source = PostsSource::Remote
  …
end

dgorodnichy

posts = Medium.new
posts.source = PostsSource::Fake
posts.user_posts

dgorodnichy

posts = Medium.new('dhh')
posts.source = PostsSource::Remote
posts.user_posts