How do I query with '.includes' across more than two tables?

Question

I have the following associations:

class Captain
  has_many :boats
end

class Boat
  belongs_to :captain
  has_many :classifications
end

class Classification
  has_many :boats
end

I want to find out which captains have boats that have classifications with :name attributes of "catamaran."

This has been my best guess so far: Captain.includes(:boats, :classifications).where(:boats => {:classifications => {:name => "catamaran"}})

Answer 1

Try this

Captain.joins(boats: :classifications).where(classifications: { name: "catamaran" })

This query results in following SQL query

SELECT * FROM `captains` 
   INNER JOIN `boats` ON `boats`.`captain_id` = `captains`.`id` 
   INNER JOIN `join_table` ON `join_table`.`boat_id` = `boat`.`id`     
   INNER JOIN `classifications` ON `join_table`.`classification_id` = `classifications`.id