Question

I’m struggling to figure out how to achieve this count.
Models are User, Test, Grade

User has_many Tests, Tests has_many Grades.

each grade has a calculated score (strong_pass, pass, fail, strong_fail).

how can I get a count of each grade category?

For clarity, a User might take a Math test 4 times until they pass it. they might receive grades in the spectrum (pass, fail, etc..)

but I want to know, of all tests taken for user X, how many passes, how many fails?

user.tests.grades.passed.count is what I hoped would work. but doesn’t
(I do have named scopes for ‘passed’, ‘failed’, etc.. in Grade model)

Class Grade

  def self.passed
    where(:grade => "passed")
  end

  def self.failed
    where(:grade => "failed")
  end

end

Answer 1

You should be able to do this:

class User < ActiveRecord::Base
  has_many :tests
  has_many :grades, through: :tests
end

user = User.first

user.grades.passed.count
user.grades.failed.count