How to create tons of Rails applications

Article originally published here : https://www.bootrails.com/blog/how-to-create-tons-rails-applications/

1. Motivation

At BootrAils, we are using this script every (working !) day. It allows you to :

grab any concept,
isolate a bug quickly,
play with new Rails features,

... without any side effect.

Side note for beginners : It's also an excellent way to improve your Ruby-on-Rails skills. The more you create new apps from scratch, the more you understand the directory structure, the philosophy, and the internals of Rails.

2. The trick

Open ~.bash_profile on your linux-based computer.

We will create a bash function, named cnra (an acronym that means "create new rails application"). Acronyms are very handy to avoid remembering every shortcut.

# inside ~.bash_profile

#
# Usage :
# $> cnra myapp 7.0.0 --minimal --database=postgresql
#
cnra ()
{  
  # create dir, dive into dir, require desired Rails version
  mkdir -p -- "$1" && cd -P -- "$1"
  echo "source 'https://rubygems.org'" > Gemfile
  echo "gem 'rails', '$2'" >> Gemfile

  # install rails, create new rails app
  bundle install
  bundle exec rails new . --force ${@:3:99}
  bundle update

  # Create a default controller
  echo "class HomeController < ApplicationController" > app/controllers/home_controller.rb
  echo "end" >> app/controllers/home_controller.rb

  # Create a default route
  echo "Rails.application.routes.draw do" > config/routes.rb
  echo '  get "home/index"' >> config/routes.rb
  echo '  root to: "home#index"' >> config/routes.rb
  echo 'end' >> config/routes.rb

  # Create a default view
  mkdir app/views/home
  echo '<h1>This is h1 title</h1>' > app/views/home/index.html.erb

  # Create database and schema.rb
  bin/rails db:create
  bin/rails db:migrate
}

Note the trick ${@:3:99} that means "all remaining CLI args, from the 3rd one to the last one."

Otherwise, comments should be self-explanatory. If not, just contact us :)

Now type

$> source ~/.bash_profile

So that your terminal will be aware of what changed inside your .bash_profile.

Usage

Open your terminal

$> cnra myapp 7.0.0 --minimal -d=postgresql

1st CLI arg is "myapp" : the name of the new app
2nd CLI arg is 7.0.0 : the version of Rails you want to try
3rd CLI arg is --minimal -d=postgresql : PostGre is a production-ready database you can easily use locally.

Note that --minimal and -d=postgresql are optionals.

Going further

We personally like the minimal flag (to avoid all the default gems we probably won't need), and the "postgresql" database - a production-ready, widely used database in the Ruby-on-Rails world. So we use another shortcut, based on the previous one.

cnra7mp() {
  cnra myapp 7.0.0 --minimal -d=postgresql
}

All we have to do now each time we want to try something with Rails is the following :

$/workspace> cnra7mp
$/workspace/myapp> bin/rails server

And voilà ! A new Rails application up and running, no need to create the database, or build a default welcome page : our app is ready for experimentations.