Rails User Engine - Adding permissions

A while back, there was discussion on the engines mailing list on how to add permissions for different roles in the database for the user engine.

My preferred way of doing this is using migrations. I will illustrate it here using an example, say we have a controller about with actions ["terms", "privacy", "faq", "about"] and we want to give permissions to both Guest and User roles to have access to this.

So, to write a migration for this, fire up a shell and type:

ruby script\generate migration AddPermissionsData

This will create a new migration file in the `db\migrate' folder:

class AddPermissionsData < ActiveRecord::Migration
  def self.up
  end

  def self.down
  end
end

Now, to add permissions modify the above file, and add the following code:

class AddPermissionsData < ActiveRecord::Migration
  def self.up
    guest_role = Role.find_by_name("Guest")
    user_role = Role.find_by_name("User")
    controller_actions = {:about => ["terms", "privacy", 
                                          "faq", "about"] }
    controller_actions.each do |controller,actions|
      for action in actions
        permission = Permission.find_by_controller_and_action(
                                           controller.to_s,action)
        if permission
          permission.roles << guest_role
          permission.roles << user_role
        end
      end
    end
  end

  def self.down
    guest_role = Role.find_by_name("Guest")
    user_role = Role.find_by_name("User")
    controller_actions = {:about => ["terms", "privacy",
                                            "faq", "about"]}
    controller_actions.each do |controller,actions|
      for action in actions
        permission = Permission.find_by_controller_and_action(
                                             controller.to_s,action)
        if permission
          permission.roles.delete guest_role
          permission.roles.delete user_role
        end
      end
    end
  end
end

The code in self.down should remove whatever was added in self.up.

Important: Before running the above migration, don't forget to run rake sync_permissions.

If you know of a better approach of doing the above then please post it as a comment.