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?