ManaPotion

Do you need to limit some resource's creation rate? It's simple to do it with ManaPotion!

The ManaPotion gem helps you validate any ActiveRecord::Base model so that no user will be able to create it faster than some given limit. Really useful when you're using an expensive API and don't want some user to bankrupt you.

Add this line to your application's Gemfile:

gem 'mana-potion'

And then execute:

$ bundle

Or install it yourself as:

$ gem install mana-potion

You just need to include the ManaPotion::Pool module in your model's class and call the mana_pool_for macro. It defaults to limiting the creation by 1 per day.

class Post < ActiveRecord::Base
  include ManaPotion::Pool
  belongs_to :user

  mana_pool_for :user
end

user = User.create!
user.posts.create! # No problem here
user.posts.create! # Raises an ActiveRecord::RecordInvalid exception

require 'timecop'
Timecop.travel 1.day.from_now
user.posts.create! # No problem here

If you want to configure the limit and/or period, just pass them as parameters to the macro:

class Post < ActiveRecord::Base
  include ManaPotion::Pool
  belongs_to :user

  mana_pool_for :user, limit: 10, period: 1.hour
end

The limit and period options also accept procs, so you can dynamically define their values:

class Post < ActiveRecord::Base
  include ManaPotion::Pool
  belongs_to :user

  mana_pool_for :user, limit: -> { limit }, period: -> { period }

  def limit
    user.premium? ? 20 : 10
  end

  def period
    user.premium? ? 1.hour : 1.day
  end
end

Trying to create a Post without an User will raise an error:

Post.create! # Raises a MissingOwnerError

To allow nil value for User, include the allow_nil: true option:

class Post < ActiveRecord::Base
  include ManaPotion::Pool
  belongs_to :user

  mana_pool_for :user, allow_nil: true
end

Post.create! # Doesn't raise any errors

If you want to check the user's remaining usages, you may use the ManaPotion::CheckUsage#remaining method:

user = User.create!
ManaPotion::CheckUsage.new(Post.new, user, 5, 1.day).remaining # => 5

user.posts.create!
ManaPotion::CheckUsage.new(Post.new, user, 5, 1.day).remaining # => 4

After checking out the repo, run bin/setup to install dependencies. Then, run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release to create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

1. Fork it ( https://github.com/[my-github-username]/mana-potion/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request