Right way to Active Record DB modeling

Question

If I use STI, I'll have several nil columns on my DB and I don't know if I can use Polymorphic Associations in cases like that. Any tip or some references?

[!How the right way to modeling somethink like that?] [1][1]

Answer 1

Though I don't understand the language completely from the image. If I understand I think one Coordinator has many Junior employee and senior employee. And seems like both employee table has the same type of column. What I would do in this case is, I would just create one employee table and keep a enum column of role. The model would look something like below-

class Coordinator
 has_many: :employees
end

class Employee
 belongs_to: :coordinator

 enum role: { junior: 0, senior: 1 }
end

If you haven't used enum in Rails yet, it's really handy. Take a look