How to set up associations in Ruby on Rails?

Question

I'm building a sample app for practice and am having trouble determining the best way to organize my models and associations. So let's just say I have 3 models:

1. Schools
2. Classes
3. Students

I want:

• schools to have many classes
• classes to have many students
• classes to belong to a school
• students to be enrolled in many classes in many different schools

The associations are making me dizzy, I'm not sure which ones to use. Help would be greatly appreciated.

Answer 1

Renamed class to course, as the class name Class is already taken. A join class such as enrollments would handle your many to many course <=> student relationship.

class School
  has_many :courses
end

class Course
  belongs_to :school
  has_many :enrollments
  has_many :students, :through => :enrollments
end

class Student
  has_many :enrollments
  has_many :courses, :through => :enrollments
end

class Enrollment
  belongs_to :course
  belongs_to :student
end