Rails migrations are the way to move between one state of a database and another. add column drop column, Rails 4 Rails 5 active record migrations rollback
Debug is a state of mind, and you should always be in it.
Antipattern fat model skinny controllers using composition to create a composite object Rails models as persistence-layer only and separated from business objects
Rails Autoloading is what happens in the background that most developers don’t even think about. Rails Autoload is something that is important for you to know about. Rails will automatically load certain files your Rails app application when it boots up.
If you are inside of a Rake task, you might be confused if your Rails environment is not available.
N+1 queries need to be solved in Ruby on Rails by identifying where the Active Relation object is created and adding a joins or includes to prefetch eagerload to optimize ActiveRecord just-in-time loading.