I'm creating a web app which consists of schools, courses, students, and teachers.
A school can have many courses and a course has one teacher and many students.
The problem I am running into is that a single user could be a teacher of one course, but a student in another course (or even a student or teacher in a course in a different school). I don't want to create a model for teachers and a separate model for students because I would like to track all my users in one place. There is an enrollment table which lists which users are enrolled as students in a course.
I would like to do something like the following:
class School < ActiveRecord::Base
has_many :courses
has_many :students :through enrollments
has_many :teachers :through courses
end
class Course < ActiveRecord::Base
has_one :teacher
belongs_to :school
has_many :students :through enrollments
end
class User < ActiveRecord::Base
has_many :courses
has_many :schools
end
But if I have only a users table and not two separate students and teachers tables, this won't work.
Instead, I would have to do something like
class School < ActiveRecord::Base
has_many :users [that are teachers]
has_many :users :through enrollments [that are students]
end
How can I set up my model and associations to make this work?
Thanks.
Use inheritance.
Teachers and students are inherited from the users model. You can consult http://api.rubyonrails.org/classes/ActiveRecord/Base.html for further information. Be sure to create a "type" column or equivalent in your User table.
class User < ActiveRecord::Base
end
class Student < User
end
class Teacher < User
end
Rails will treat them individually, but they will still exist in the User table.Let me know if you need further assistance
I may have missed something, but it should work if you add the class_name to your relation with "User":
class School < ActiveRecord::Base
has_many :courses
has_many :students :through enrollments, :class_name => "User"
has_many :teachers :through courses, :class_name => "User"
end
class Course < ActiveRecord::Base
has_one :teacher, :class_name => "User"
belongs_to :school
has_many :students :through enrollments, , :class_name => "User"
end
class User < ActiveRecord::Base
has_many :courses
has_many :schools
end
Add a teachers_id column to courses and use belongs_to instead of has_one. Then add a class_name option.
class School < ActiveRecord::Base
has_many :courses
has_many :students :through enrollments
has_many :teachers :through courses
end
class Course < ActiveRecord::Base
belongs_to :teacher, :class_name => 'User'
belongs_to :school
has_many :students :through enrollments
end
class User < ActiveRecord::Base
has_many :courses
has_many :schools, :through enrollments
has_many :teachers, :through :courses
end
