Counter Caching for MongoMapper::Document

Examples:

  class Post
    belongs_to :user
    counter_cache :user
  end

  or:

  class Post
    belongs_to :user
    counter_cache :user, :custom_posts_count
  end

Field names follow rails conventions, so counter_cache :user will increment the Integer field `posts_count’ on User

Alternatively, you can also use the more common ActiveRecord syntax:

  class Post
    belongs_to :user, :counter_cache => true
  end

Or with an alternative field name:

  class Post
    belongs_to :user, :counter_cache => :custom_posts_count
  end