Rails创建表迁移是否应该具有created_at和updated_at？

Question

In my experience, Rails g migration create table migrations always added timestamps to the table. But that is not happening:

rails g migration CreateFoo bar:references

class Foo < ActiveRecord::Migration
  def change
    create_table :foos do |t|
      t.references :bar, index: true
    end
  end
end

Is this expected behavior? Did this change in Rails 4?

ActiveRecord 4.1.6

Answer 1

timestamps are only created with generating models.

here's an example from the guide.

http://guides.rubyonrails.org/migrations.html

$ bin/rails generate migration CreateProducts name:string part_number:string

generates

class CreateProducts < ActiveRecord::Migration
  def change
    create_table :products do |t|
      t.string :name
      t.string :part_number
    end
  end
end

up

You can make a suggestion by looking at provided code examples there.

Also look at:

rails g migration --help
rails g model --help

and you will see that timestamps are only provided automatically with "g model" (and you can actually disable it for models)

Answer 2

Use Rails generate model function to create model, migration and test/spec:

rails g model CreateFoo bar:references

This will add the t.timestamps in your migration.