active_hash_fields

An ActiveRecord extension to add serialized hash fields that act like objects

A User should be able to set various notification options for various events. For example, he may want to receive an email notification when someone leaves a comment for his blog post, but not when someone replies with a comment to his comment.

This can usually be solved by either creating an additional associated model like NotificationSettings or by creating numerous fields in the User model itself. Not quite efficient either way.

Here's the solution. First add a field to store all nested fields as a serialized hash:

class AddNotificationsToUsers < ActiveRecord::Migration
  def change
    add_column :users, :notifications, :text
  end
end

Then define nested fields in your model:

class User < ActiveRecord::Base

  active_hash_fields :notitications,
    comments_to_my_posts:    true,
    comments_to_my_comments: false,
    someone_friended_me:     true,
    new_private_message:     true    

end

Now you can do things like:

# Default values are the ones set in the model,
# here we just redefine one
user = User.new(notifications: { comments_to_my_posts: false })

user.notifications.comments_to_my_posts # => false
user.notifications.new_private_message  # => true

IMPORTANT NOTE! If you don't set a default value for the field, it will be ignored, that is:

user.notifications.some_non_existent_field = true
user.notifications.some_non_existent_field # => nil

  gem install active_hash_fields