Model structure in many to many relationship - ruby-on-rails

Question

I have two models Students and Colleges for which I want to be able to list the college's a student has applied for and also the list of students applying for a college.
I have this form that creates a Student and also selects colleges through the checkbox
<div class="row">
<div class="col-md-6 col-md-offset-3">
<h3>Add Students</h3>
<%= simple_form_for #student do |f| %>
<%= f.input :name %>
<%= f.input :sex, collection: ["Male", "Female"] %>
<%= f.input :age, collection: 15..100 %>
<%= f.input :dob %>
<%= f.input :current_school %>
<%= f.input :current_level %>
<%= f.input :country, priority: [ "Singapore" ] %>
<%= f.input :sat_score %>
<%= f.input :applied_colleges, collection: College.all,group_method: :id, as: :check_boxes %> <%= f.input :current_mentor, collection: Mentor.all, group_method: :name, as: :select %>
<%= f.button :submit %>
<% end %>
</div>
This is the schema for the app:
ActiveRecord::Schema.define(version: 20150131123428) do
create_table "colleges", force: true do |t|
t.string "name"
t.string "country"
t.integer "sat_min_score"
t.integer "sat_max_score"
t.integer "tution_fees"
t.datetime "created_at"
t.datetime "updated_at"
t.integer "student_list"
end
create_table "mentors", force: true do |t|
t.string "name"
t.string "sex"
t.integer "age"
t.date "dob"
t.text "bio"
t.datetime "created_at"
t.datetime "updated_at"
end
create_table "students", force: true do |t|
t.string "name"
t.string "sex"
t.integer "age"
t.date "dob"
t.string "current_school"
t.string "current_level"
t.string "country"
t.integer "sat_score"
t.datetime "created_at"
t.datetime "updated_at"
t.integer "current_mentor_id"
t.string "applied_colleges"
t.string "current_mentor"
end
add_index "students", ["current_mentor_id"], name: "index_students_on_current_mentor_id"
end
This is the student model
class Student < ActiveRecord::Base
serialize :applied_colleges, Array
has_one :mentor
validates :name, presence: true, length: { maximum:50 }
validates :age, presence: true, numericality: { lesser_than_or_equal_to: 120, only_integer: true}
validates :sat_score, presence: true, numericality: {lesser_than_or_equal_to: 1600, only_integer: true}
def self.college_id_to_college_name(applied_colleges)
colleges = []
applied_colleges.each do |var|
colleges << var.to_i
end
#college_list = []
colleges.each do |var|
#college_list << College.find_by(id:var)
end
#college_list.delete_at(#college_list.length-1)
#college_list
end
def self.save_applied_student_id_to_student_joined_column_for_college(student_id,college_list)
college_list.each do |college|
college.student_list << student_id
end
end
end
This is the College model
class College < ActiveRecord::Base
validates :name, presence:true, length: { maximum:50 }
validates :sat_min_score, presence:true, numericality: {lesser_than: 2400, only_integer: true}
validates :sat_max_score, presence:true, numericality: {lesser_than_or_equal_to: 2400, only_integer: true}
end
I am very confused with the modelling between student and college The model needs to be such that each student object has the list of colleges he has applied to and each college has the list of students who has applied.
Currently what I am doing for saving the list of colleges a student has applied to by saving the id of the colleges from the colleges chosen through the checkbox in the form and saving it in a column.
I am thinking to insert the student id of every student in the column called student_list. But this seems like a bad way.
I want to model Students and Colleges in such a way that each student object has the list of colleges he has applied to and each college object has the list of students who has applied.
How do I model this? What would be the necessary migration required?

Answer 1

If you want to have a good way to join students and colleges, I'd make a Model called Application [beware, this might be a reserved word, so you may need a different name for the model -- don't recall off the top of my head] (needs a student_id, and a college_id). Student has_many Applications, has_many Colleges through Applications. Reverse for Colleges, has_many applications, has_many students through applications. Application belongs_to student, and belongs_to college.
Though at this point, you're mixing the traditional definitions of students and applicants. Generally, people might be applicants, and applicants might be enrolled students.