INCLUDES - EAGER LOAD
multiple relationships
users = User.includes(:address, :friends)
Nested relationships is possible using a Hash:
users = User.includes(:address, friends: [:address, :followers])
Conditions with references:
User.includes(:posts).where('posts.name = ?', 'example').references(:posts)
SHK:
Coupon.includes(:booking, booking:[:space]).all.each{|c| puts c.booking.space.title if c.booking}