How do I run a Ruby file in a Rails environment?

Question

The simplest way is with rails runner because you don't need to modify your script.

http://guides.rubyonrails.org/command_line.html#rails-runner

Just say rails runner script.rb

Simply require environment.rb in your script. If your script is located in the script directory of your Rails app do

require File.expand_path('../../config/environment', __FILE__)

You can control the environment used (development/test/production) by setting the RAILS_ENV environment variable when running the script.

RAILS_ENV=production ruby script/test.rb

Runner runs Ruby code in the context of Rails non-interactively.

From rails runner command:

Usage: runner [options] ('Some.ruby(code)' or a filename)

    -e, --environment=name           Specifies the environment for the runner to operate under (test/development/production).
                                     Default: development

    -h, --help                       Show this help message.

You can also use runner as a shebang line for your scripts like this:

-------------------------------------------------------------
#!/usr/bin/env /Users/me/rails_project/script/rails runner

Product.all.each { |p| p.price *= 2 ; p.save! }
-------------------------------------------------------------

This is an old question, but in my opinion I often find it helpful to create a rake task... and it's actually very easy.

In lib/tasks/example.rake:

namespace :example do

desc "Sample description you'd see if you ran: 'rake --tasks' in the terminal"
task create_user: :environment do
  User.create! first_name: "Foo", last_name: "Bar"
end

And then in the terminal run:

rake example:create_user

Locally this will be run in the context of your development database, and if run on Heroku it will be run while connected to your production database. I find this especially useful to assist with migrations, or modified tables.