Heroku发布前准备

group :development, :test do
  gem 'byebug', platform: :mri
  gem 'sqlite3', '~> 1.3.13'
end

group :production do
  gem 'pg'
end

修改 Gemfile

• bundle install

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

修改routes.rb　注意：修改首页的代码是不固定的　

• git add .
• git commit -m "add root path"