Validation on has_many :through relations

Ruby on Rails
2

Just so I’m clear we have:

class Parent
  has_many :children
  has_many :grandchildren, through: :children
end

class Child
  belongs_to :parent
  has_many :grandchildren
end

class Grandchild
  belongs_to :child
  has_one :parent, through: :child
end

So when you save a grandchild are you checking the parent is valid? or is present?

I only ask because I wouldn’t expect to find a grandchild_id or parent_id on either end of a has_many :through.