Need help with these counter_cache associations

Ruby on Rails
1

I have a long association between Family and Lesson but I want to add a counter_cache so I can easily display family.lessons_count on my Family index page.

Calling family.lessons.count works fine but of course on the index page I’m calling it many times from the view causing far too many queries just for a count column in a table.

Where do I put the counter_cache column and how do I reference it in (which?) model?

(Setting up a separate counter_cache for family.students_count was easy because a student directly belongs_to a family)

# family.rb
class Family < ActiveRecord::Base
  has_many :students
  has_many :school_classes, through: :students
  has_many :lessons, through: :school_classes
  ...
end

# student.rb
class Student < ActiveRecord::Base
  belongs_to :family, counter_cache: true # this one works fine
  has_many :class_memberships
  has_many :school_classes, through: :class_memberships
  has_many :lessons, through: :school_classes
  ...
end

# school_class.rb
class SchoolClass < ActiveRecord::Base
  has_many :class_memberships
  has_many :students, through: :class_memberships
  has_many :lessons
  ...
end

# lesson.rb
class Lesson < ActiveRecord::Base
  belongs_to :school_class
  has_many :students, through: :school_class
  ..
end

My app is still on Rails 3.2.14 so none of the new hotness here please :slight_smile: