active_sample by JuanitoFatas

Microscope adds useful scopes targeting ActiveRecord boolean, date and datetime fields. Maintained by mirego on GitHub, where it has earned 61 stars from the community.

A gem to define virtual associations on Rails models. Maintained by onyxblade on GitHub, where it has earned 67 stars from the community.

Some ActiveModel/ActiveRecord validators. Maintained by fnando on GitHub, where it has earned 97 stars from the community.