Rails ガイド

$ rails new my_app
     create
     create  README.md
     create  Rakefile
     create  config.ru
     create  .gitignore
     create  Gemfile
     create  app
     ...
     create  tmp/cache
     ...
        run  bundle install

$ rails new petstore --database=postgresql
      create
      create  app/controllers
      create  app/helpers
...

# PostgreSQL. Versions 9.3 and up are supported.
#
# Install the pg driver:
#   gem install pg
# On macOS with Homebrew:
#   gem install pg -- --with-pg-config=/usr/local/bin/pg_config
# On Windows:
#   gem install pg
#       Choose the win32 build.
#       Install PostgreSQL and put its /bin directory on your path.
#
# Configure Using Gemfile
# gem "pg"
#
default: &default
  adapter: postgresql
  encoding: unicode

  # For details on connection pooling, see Rails configuration guide
  # https://guides.rubyonrails.org/configuring.html#database-pooling
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>

development:
  <<: *default
  database: petstore_development
...

$ rails --help
Usage:
  bin/rails COMMAND [options]

You must specify a command. The most common commands are:

  generate     Generate new code (short-cut alias: "g")
  console      Start the Rails console (short-cut alias: "c")
  server       Start the Rails server (short-cut alias: "s")
  ...

All commands can be run with -h (or --help) for more information.

In addition to those commands, there are:
about                               List versions of all Rails ...
assets:clean[keep]                  Remove old compiled assets
assets:clobber                      Remove compiled assets
assets:environment                  Load asset compile environment
assets:precompile                   Compile all the assets ...
...
db:fixtures:load                    Load fixtures into the ...
db:migrate                          Migrate the database ...
db:migrate:status                   Display status of migrations
db:rollback                         Roll the schema back to ...
db:schema:cache:clear               Clears a db/schema_cache.yml file
db:schema:cache:dump                Create a db/schema_cache.yml file
db:schema:dump                      Create a database schema file (either db/schema.rb or db/structure.sql ...
db:schema:load                      Load a database schema file (either db/schema.rb or db/structure.sql ...
db:seed                             Load the seed data ...
db:version                          Retrieve the current schema ...
...
restart                             Restart app by touching ...
tmp:create                          Create tmp directories ...

$ cd my_app
$ bin/rails server
=> Booting Puma
=> Rails 7.1.0 application starting in development
=> Run `bin/rails server --help` for more startup options
Puma starting in single mode...
* Version 3.12.1 (ruby 2.5.7-p206), codename: Llamas in Pajamas
* Min threads: 5, max threads: 5
* Environment: development
* Listening on tcp://localhost:3000
Use Ctrl-C to stop

$ bin/rails server -e production -p 4000

$ bin/rails generate
Usage:
  bin/rails generate GENERATOR [args] [options]

...
...

Please choose a generator below.

Rails:
  assets
  channel
  controller
  generator
  ...
  ...

$ bin/rails generate controller
Usage:
  bin/rails generate controller NAME [action action] [options]

...
...

Description:
    ...

    To create a controller within a module, specify the controller name as a path like 'parent_module/controller_name'.

    ...

Example:
    `bin/rails generate controller CreditCards open debit credit close`

    Credit card controller with URLs like /credit_cards/debit.
        Controller: app/controllers/credit_cards_controller.rb
        Test:       test/controllers/credit_cards_controller_test.rb
        Views:      app/views/credit_cards/debit.html.erb [...]
        Helper:     app/helpers/credit_cards_helper.rb

$ bin/rails generate controller Greetings hello
     create  app/controllers/greetings_controller.rb
      route  get 'greetings/hello'
     invoke  erb
     create    app/views/greetings
     create    app/views/greetings/hello.html.erb
     invoke  test_unit
     create    test/controllers/greetings_controller_test.rb
     invoke  helper
     create    app/helpers/greetings_helper.rb
     invoke    test_unit

class GreetingsController < ApplicationController
  def hello
    @message = "こんにちは、ご機嫌いかがですか？"
  end
end

<h1>ごあいさつ</h1>
<p><%= @message %></p>

$ bin/rails server
=> Booting Puma...

$ bin/rails generate model
Usage:
  bin/rails generate model NAME [field[:type][:index] field[:type][:index]] [options]

...

ActiveRecord options:
      [--migration], [--no-migration]        # Indicates when to generate migration
                                             # Default: true

...

Description:
    Generates a new model. Pass the model name, either CamelCased or
    under_scored, and an optional list of attribute pairs as arguments.

...

$ bin/rails generate scaffold HighScore game:string score:integer
    invoke  active_record
    create    db/migrate/20190416145729_create_high_scores.rb
    create    app/models/high_score.rb
    invoke    test_unit
    create      test/models/high_score_test.rb
    create      test/fixtures/high_scores.yml
    invoke  resource_route
     route    resources :high_scores
    invoke  scaffold_controller
    create    app/controllers/high_scores_controller.rb
    invoke    erb
    create      app/views/high_scores
    create      app/views/high_scores/index.html.erb
    create      app/views/high_scores/edit.html.erb
    create      app/views/high_scores/show.html.erb
    create      app/views/high_scores/new.html.erb
    create      app/views/high_scores/_form.html.erb
    invoke    test_unit
    create      test/controllers/high_scores_controller_test.rb
    create      test/system/high_scores_test.rb
    invoke    helper
    create      app/helpers/high_scores_helper.rb
    invoke      test_unit
    invoke    jbuilder
    create      app/views/high_scores/index.json.jbuilder
    create      app/views/high_scores/show.json.jbuilder
    create      app/views/high_scores/_high_score.json.jbuilder

$ bin/rails db:migrate
==  CreateHighScores: migrating ===============================================
-- create_table(:high_scores)
   -> 0.0017s
==  CreateHighScores: migrated (0.0019s) ======================================

$ bin/rails server

$ bin/rails console -e staging

$ bin/rails console --sandbox
Loading development environment in sandbox (Rails 7.1.0)
Any modifications you make will be rolled back on exit
irb(main):001:0>

irb> app.root_path
=> "/"

irb> app.get _
Started GET "/" for 127.0.0.1 at 2014-06-19 10:41:57 -0300
...

irb> helper.time_ago_in_words 30.days.ago
=> "about 1 month"

irb> helper.my_custom_helper
=> "my custom helper"

$ bin/rails dbconsole --database=animals

$ bin/rails runner "Model.long_running_method"

$ bin/rails runner -e staging "Model.long_running_method"

$ bin/rails runner lib/code_to_be_run.rb

$ bin/rails generate model Oops
      invoke  active_record
      create    db/migrate/20120528062523_create_oops.rb
      create    app/models/oops.rb
      invoke    test_unit
      create      test/models/oops_test.rb
      create      test/fixtures/oops.yml

$ bin/rails destroy model Oops
      invoke  active_record
      remove    db/migrate/20120528062523_create_oops.rb
      remove    app/models/oops.rb
      invoke    test_unit
      remove      test/models/oops_test.rb
      remove      test/fixtures/oops.yml

$ bin/rails about
About your application's environment
Rails version             7.1.0
Ruby version              2.7.0 (x86_64-linux)
RubyGems version          2.7.3
Rack version              2.0.4
JavaScript Runtime        Node.js (V8)
Middleware:               Rack::Sendfile, ActionDispatch::Static, ActionDispatch::Executor, ActiveSupport::Cache::Strategy::LocalCache::Middleware, Rack::Runtime, Rack::MethodOverride, ActionDispatch::RequestId, ActionDispatch::RemoteIp, Sprockets::Rails::QuietAssets, Rails::Rack::Logger, ActionDispatch::ShowExceptions, WebConsole::Middleware, ActionDispatch::DebugExceptions, ActionDispatch::Reloader, ActionDispatch::Callbacks, ActiveRecord::Migration::CheckPending, ActionDispatch::Cookies, ActionDispatch::Session::CookieStore, ActionDispatch::Flash, Rack::Head, Rack::ConditionalGet, Rack::ETag
Application root          /home/foobar/my_app
Environment               development
Database adapter          sqlite3
Database schema version   20180205173523

$ bin/rails notes
app/controllers/admin/users_controller.rb:
  * [ 20] [TODO] any other way to do this?
  * [132] [FIXME] high priority for next deploy

lib/school.rb:
  * [ 13] [OPTIMIZE] refactor this code to make it faster
  * [ 17] [FIXME]

$ bin/rails notes --annotations FIXME RELEASE
app/controllers/admin/users_controller.rb:
  * [101] [RELEASE] We need to look at this before next release
  * [132] [FIXME] high priority for next deploy

lib/school.rb:
  * [ 17] [FIXME]

config.annotations.register_tags("DEPRECATEME", "TESTME")

$ bin/rails notes
app/controllers/admin/users_controller.rb:
  * [ 20] [TODO] do A/B testing on this
  * [ 42] [TESTME] this needs more functional tests
  * [132] [DEPRECATEME] ensure this method is deprecated in next release

config.annotations.register_directories("spec", "vendor")

$ bin/rails notes
app/controllers/admin/users_controller.rb:
  * [ 20] [TODO] any other way to do this?
  * [132] [FIXME] high priority for next deploy

lib/school.rb:
  * [ 13] [OPTIMIZE] Refactor this code to make it faster
  * [ 17] [FIXME]

spec/models/user_spec.rb:
  * [122] [TODO] Verify the user that has a subscription works

vendor/tools.rb:
  * [ 56] [TODO] Get rid of this dependency

config.annotations.register_extensions("scss", "sass") { |annotation| /\/\/\s*(#{annotation}):?\s*(.*)$/ }

$ bin/rails notes
app/controllers/admin/users_controller.rb:
  * [ 20] [TODO] any other way to do this?
  * [132] [FIXME] high priority for next deploy

app/assets/stylesheets/application.css.sass:
  * [ 34] [TODO] Use pseudo element for this class

app/assets/stylesheets/application.css.scss:
  * [  1] [TODO] Split into multiple components

lib/school.rb:
  * [ 13] [OPTIMIZE] Refactor this code to make it faster
  * [ 17] [FIXME]

spec/models/user_spec.rb:
  * [122] [TODO] Verify the user that has a subscription works

vendor/tools.rb:
  * [ 56] [TODO] Get rid of this dependency

desc "手短でクールなタスクの概要"
task task_name: [:prerequisite_task, :another_task_we_depend_on] do
  # マジックをここに書く
  # 有効なRubyコードなら何でも書ける
end

task :task_name, [:arg_1] => [:prerequisite_1, :prerequisite_2] do |task, args|
  argument_1 = args.arg_1
end

namespace :db do
  desc "何もしないタスク"
  task :nothing do
    # 本当に何もしない
  end
end

$ bin/rails task_name
$ bin/rails "task_name[value 1]"                 # 引数の文字列全体を引用符で囲むこと
$ bin/rails "task_name[value 1, value2, value3]" # 複数の引数はカンマで区切る
$ bin/rails db:nothing

task task_that_requires_app_code: [:environment] do
  User.create!
end