Rails in one lesson

Models views controllers

Rails splits every feature into three roles with fixed homes. Models hold data and rules, views render pages, and controllers connect the two.

The sketch below shows where one todo feature lives inside a fresh application.

# app models todo file holds the model # app views todos folder holds the pages # app controllers todos file holds the actions

Routes

Routes map URLs to controller actions in one central file. One resources line creates the full set of list, show, create, update, and delete paths.

Read the routes file as the table of contents for the whole application.

Rails.application.routes.draw do resources :todos root "todos#index" end

ActiveRecord sketch

ActiveRecord models look like plain Ruby classes with database powers mixed in. The sketch below runs without any database at all.

Learn the shape first with plain attributes, then let Rails add persistence, validations, and relations later.

class Todo attr_accessor :title, :done def initialize(title) @title = title @done = false end end

How a Rails app starts

A new Rails application starts from two typed commands. Install the rails gem once, then generate a fresh project folder.

Nothing below boots an application. Treat this lesson as a map, then build the two capstones with plain Ruby first.

Install the gem

gem install rails

39 gems installed

Check the version

rails -v

Rails 8.1.4.1

Generate the application

rails new blog

create config/recurring.yml create db/queue_schema.rb create bin/jobs gsub config/environments/production.rb create db/cable_schema.rb force config/cable.yml

Look at what was generated

ls blog

Dockerfile Gemfile Gemfile.lock README.md Rakefile app bin config config.ru db lib log public script storage test tmp vendor

The output above comes from the official ruby:3 image, which has the build tools Rails needs. On a bare machine the same commands work after a compiler and the usual headers are installed.

Next: Net::HTTP in depth

Article author: Arthur Isaev