Updating models in rails / migrations

Question

Let's say I used the following command to create a "User" model:

script/generate model User username:string

This creates the user.rb file along with the migration rb file to create the Users table. Now, I want to add an email column to my User model. What's the best way to do that? Do I do it manually and write the migration file by hand or is there a shortcut for doing it? If I write the migration by hand, do I have to name it the same way as the previous migration script (with a timestamp in front) to guarantee that it runs after the previous migration?

Answer 1

Don't worry about the timestamp. It will be generated automatically. You can do a

rails generate migration add_email_to_user email:string

This would automatically create a migration file which would look like this:

class AddEmailToUser < ActiveRecord::Migration
  def self.up
    add_column :email, :string
  end

  def self.down
    remove_column :email
  end
end

the file would have the timestamp in the format YYYYMMDDHHMMSS (For Rails 2.1 and above) appended in front of the filename.

Answer 2

The Guide has information about generating migrations. If you use the rails generator, it will create correctly named files:

ruby script/generate migration AddEmailToUser email:string