CODEWITHSUNDEEP
ruby-on-railsmodel-associationsrails-activerecord
Maximus S
Maximus S

Reputation: 11095

Self-referential association

It's a follow-up question from this.

This is my current setting to make a teacher-student relationship.

User Model

  has_many :teacher_links, :foreign_key => :student_id, :dependent => :destroy, :class_name => "TeacherStudentLink"
  has_many :student_links, :foreign_key => :teacher_id, :dependent => :destroy, :class_name => "TeacherStudentLink"
  has_many :students, :through => :student_links
  has_many :teachers, :through => :teacher_links

TeacherStudentLink Model

class TeacherStudentLink < ActiveRecord::Base
  attr_accessible :user_id, :student_id, :teacher_id

  belongs_to :user
  belongs_to :student, :class_name => "User"
  belongs_to :teacher, :class_name => "User"
end

It seems awkward to me because the teacher_student_links table has three columns: user, student, teacher. User can have many teachers, and he can also have many students. If I don't have the teacher column, and just pretend "user" is a "teacher", everything works out perfectly. Is there a way to fix this issue?

Upvotes: 0

Views: 309

Answers (1)

house9
house9

Reputation: 20614

what cheeseweasel said in the comments, your link should not have a user_id

class TeacherStudentLink < ActiveRecord::Base
  attr_accessible :student_id, :teacher_id

  belongs_to :student, :class_name => "User", :foreign_key => :student_id
  belongs_to :teacher, :class_name => "User", :foreign_key => :teacher_id
end
  • belongs_to foreign_key specifies the foreign key on the current table (link)
  • has_many foreign_key specifies the foreign key on the other table (link)

Upvotes: 1

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