Conventions used

There are a number of text conventions used throughout this book.

Code in text: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: “All we need to make this code work as we want is to add a couple of has_many declarations to our models.”

A block of code is set as follows:

class User < ApplicationRecord
  has_many :posts, -> { order(id: :desc) }
end
class Post < ApplicationRecord
  has_many :comments, -> { order(id: :desc) }
end

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

Rails.application.routes.draw do
  # The same as: resources :posts, only: %i[index]
  get "/posts", to: PostsController.action(:index)
end

Any command-line input or output is written as follows:

$ git log --format=oneline -- app/models/user.rb | wc -l

Tips or important notes

Appear like this.