Question

If I have this relationship how would I add to my view so that when I create a student I am given a textbox where I can add multiple courses for the new student?

class Student < ActiveRecord::Base
  has_and_belongs_to_many :courses
end

class Course < ActiveRecord::Base
  has_and_belongs_to_many :students
end


<%= form_for(@student) do |f| %>

    <%= f.label :name %><br />
    <%= f.text_field :name%><br />

    <%= f.label :description %><br />
    <%= f.text_field :description %><br />

    <%= f.submit %><br />
<% end %>

Answer 1

I recommend refactoring your models as follows:

class Student < ActiveRecord::Base
  has_many :enrollments
  has_many :courses, :through => :enrollments
end

class Course < ActiveRecord::Base
  has_many :enrollments
  has_many :students, :through => :enrollments
end

class Enrollment < ActiveRecord::Base
  belongs_to :student
  belongs_to :course
end

and using RyanB’s nested_form gem: https://github.com/ryanb/nested_form