Better Counters

==============

Counter cache is a great feature in Rails ActiveRecord to improve counting performance of a model's child associations by caching the number in a column.

Unfortunately it is tied to belongs_to, Many times i had to create similar custom methods from scratch just to work with delegate or simply shortcut methods or models that aren't associated through belongs_to

Here comes Better Counters with an independent syntax.

In your Gemfile add this line:

gem 'better_counters'

Run bundle install

In the following examples, we assume that we have a model User that has many Projects and many Tasks through projects, and we'd like to cache the tasks count on the User model.

First you need to create a migration and add a counter column, like tasks_count.

rails g migration AddTasksCountToUsers

Open up the generated migration file located at /db/migrate/XXXXX.rb and replace the content with something like:

def self.up
  add_column :users, :tasks_count, :integer, :default => 0

  # Fill in the new cache column with each user's tasks count
  User.reset_column_information
  User.find(:all).each do |p|
    User.update_counters p.id, :tasks_count => p.tasks.count
  end
end

def self.down
  remove_column :user, :tasks_count
end

Run rake db:migrate

Then simply on your model add the method counter_cache with a hash of models to keep the count column in.

class Task < ActiveRecord::Base
  belongs_to :project
  counter_cache :user => true

  def user
    project.user
  end
end

Based on the example above, to fetch a user's total tasks count, run: @user.tasks_count. You will no longer have to use the slow @user.tasks.count

You can use the counter cache in multiple models as long as they all have a counter column.

counter_cache :user => true, :project => true

You can override the default column name with your own:

counter_cache :user => :total_tasks

• Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet.
• Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it.
• Fork the project.
• Start a feature/bugfix branch.
• Commit and push until you are happy with your contribution.
• Make sure to add tests for it. This is important so I don't break it in a future version unintentionally.
• Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.

Copyright

Copyright (c) 2012 Ryan Sacha. See LICENSE.txt for further details.

If you happen to be bored, You can check out my Portfolio.