Migration: Adding/Removing columns are now much easier

Published on Author Akhil Bansal12 Comments

You may have noticed by now, that in Rails 2.0 changeset 7422, you can specify columns you want to add/remove in your migration by passing attribute:type pairs to the migration generator.

For example, lets assume that we need to add a column ‘role’ in users table(User model). In this case generate a migration like:

script/generate migration AddRoleToUser role:string

Output:

class AddRoleToUser < ActiveRecord::Migration
  def self.up
    add_column :users, :role, :string
  end

  def self.down
    remove_column :users, :role
  end
end

Here AddRoleToUser plays the main role. ‘Add’ specifies the we want to add column(s) and ‘User’ separated by ‘To’ specifies the table.

Similarly, if we need to remove a column ‘role’ :

 script/generate migration RemoveRoleFromUser role:string

Output:

class RemoveRoleFromUser < ActiveRecord::Migration
  def self.up
    remove_column :users, :role
  end

  def self.down
    add_column :users, :role, :string
  end
end

Here RemoveRoleFromUser plays the main role. ‘Remove’ specifies the we want to remove column(s) and ‘User’ separated by ‘From’ specifies the table.

Isn’t it cool?

12 Responses to Migration: Adding/Removing columns are now much easier

  1. Подскажите шооблончег под WordPress 2.6.2, чтобы был похож на ваш webonrails.com.

    Заранее благодарю)

  2. Hello,

    I am a beginner in rails, and I have a small question: where do I need to add “script/generate migration AddFnameToUser fname:string” in terminal or where.I work on NetBeans on ActveAdmin and I need to add some extra columns.

    Thx

    • you have to give it in terminal as script/generate migration AddFnameToUser fname:string

      you will get like this
      create db/migrate/20120702084246_addFname_to_user.rb

Leave a Reply

Your email address will not be published. Required fields are marked *