Question

I’ve got my models setup for a many-to-many relationship:

class Workshop < ActiveRecord::Base
  has_many :workshop_students
  has_many :students, :through => :student_workshops

  accepts_nested_attributes_for :students
end

class Student < ActiveRecord::Base
  has_many :student_workshops
  has_many :workshops, :through => :student_workshops

  accepts_nested_attributes_for :products
end

class StudentWorkshop < ActiveRecord::Base
  belongs_to :student
  belongs_to :workshop
end

As you can see above, a student can have many workshops and workshop can have many students.

I’ve looked at the following Rails casts: here and here. And most of the online sources I stumble across only show how to do nested forms for creating new objects within the parent form.

I don’t want to create a new object. I only want to add an existing object to the parent form. So for example. If I decide to create a new workshop, I’d like to assign existing students to the workshop.

One thing I don’t understand is, how do I link students into the workshop form? Second, when the params are passed, what should be in the controller method for update/create?

If anyone can point me to the right direction, I would appreciate it.

Answer 1

Ok, for anyone coming across the same issue in the future. The solution I came up with was in def create. I am able to access a POST attribute called student_ids, which comes in the form of an array