Rails 5.0 Beta1 版本主要改进：全新处理 WebSockets 框架 Action Cable；新 API 模式 --api；Rails 命令都提供在 bin/rails 。
The test runner now reports failures inline, so you don't have to complete the suite to see what went wrong.
ApplicationRecord has been born as a default parent class of all models created by the generators.
ActiveRecord::Relation#in_batches makes it much easier to deal with record work in batches at a time to lessen memory overloads.
Post.where('id = 1').or(Post.where('id = 2')) gives you exactly what you'd think!
No more accidentally halting Active Record callbacks because the last statement is false. Now you throw(:abort) explicitly!