Mongoid 4:
Post.create(title: 'First title', body: 'First body', status: :published) # <Post _id: 522d0fe0d43dcdc08d000003, title: "First title", body: "First body", status: :published> Post.create(title: 'Second title', body: 'Second body', status: :unpublished) # <Post _id: 522d0fead43dcdc08d000004, title: "Second title", body: "Second body", status: :unpublished> Post.in(status: [:published, :unpublished]).count # 2 Post.where(:status.in => [:published, :unpublished]).count # 2 Post.where(:status => [:published, :unpublished]).count # 0
ActiveRecord:
http://edgeapi.rubyonrails.org/classes/ActiveRecord/QueryMethods.html#method-i-where
User.where({ name: ["Alice", "Bob"]})
# SELECT * FROM users WHERE name IN ('Alice', 'Bob')