Clean, Organized, Mirror

schema.rb

  create_table "students", id: :serial, force: :cascade do |t|
    t.string "birth_year", limit: 255, null: false
    t.string "country", limit: 255, null: false
    t.string "first_name", limit: 255, null: false
    t.string "last_name", limit: 255, null: false
    t.string "student_status", limit: 255
    t.text "story", null: false
    t.integer "organization_id"
    t.index ["organization_id"], name: "index_students_on_organization_id"
  end

student.rb

class Student < ApplicationRecord
  belongs_to :organization

  has_many :payments
  has_many :student_timelines
  has_many :subscriptions

  has_many :users, through: :subscriptions

  validates :birth_year, :first_name, :last_name, :country, length: {maximum: 255}, presence: true

  validates :story, presence: true
end

student_spec.rb

require "rails_helper"

describe Student do
  context "associations" do
    it { should belong_to(:organization) }

    it { should have_many(:payments) }
    it { should have_many(:student_timelines) }
    it { should have_many(:subscriptions) }

    it { should have_many(:users).through(:subscriptions) }
  end

  context "validations" do
    it { should validate_presence_of(:birth_year) }
    it { should validate_presence_of(:country) }
    it { should validate_presence_of(:first_name) }
    it { should validate_presence_of(:last_name) }
    it { should validate_presence_of(:story) }

    it { should validate_length_of(:birth_year).is_at_most(255) }
    it { should validate_length_of(:country).is_at_most(255) }
    it { should validate_length_of(:first_name).is_at_most(255) }
    it { should validate_length_of(:last_name).is_at_most(255) }
  end
end

1. Clean spaces to distinguish different aspects of code
2. Alphabetically ordered
3. Model validation reflects database constraints.