Rails - no expected foreign keys after migration

Question

my app has 3 models, defined as follow:

class User < ActiveRecord::Base
  has_many :vehicles, dependent: :destroy
  has_one :insurance, through: :vehicle
end

class Vehicle < ActiveRecord::Base
  belongs_to :user
  has_one :insurance, dependent: :destroy
end

class Insurance < ActiveRecord::Base
  belongs_to :vehicle
end

The resulting migration does not set any foreign keys for my insurances table. I expected to have two foreign keys, something like user_id and vehicle_id.

The resulting schema.rb file looks like this:

ActiveRecord::Schema.define(version: 20160314141604) do

  create_table "insurances", force: :cascade do |t|
    t.string   "name"
    t.date     "issue_date"
    t.date     "expiry_date"
    t.datetime "created_at",  null: false
    t.datetime "updated_at",  null: false
  end

  create_table "users", force: :cascade do |t|
    t.string   "email",                  default: "", null: false
    t.string   "encrypted_password",     default: "", null: false
    t.string   "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.integer  "sign_in_count",          default: 0,  null: false
    t.datetime "current_sign_in_at"
    t.datetime "last_sign_in_at"
    t.string   "current_sign_in_ip"
    t.string   "last_sign_in_ip"
    t.string   "confirmation_token"
    t.datetime "confirmed_at"
    t.datetime "confirmation_sent_at"
    t.string   "unconfirmed_email"
    t.datetime "created_at",                          null: false
    t.datetime "updated_at",                          null: false
  end

  add_index "users", ["email"], name: "index_users_on_email", unique: true
  add_index "users", ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true

  create_table "vehicles", force: :cascade do |t|
    t.text     "name"
    t.date     "matriculation_date"
    t.integer  "user_id"
    t.datetime "created_at",         null: false
    t.datetime "updated_at",         null: false
  end

  add_index "vehicles", ["user_id"], name: "index_vehicles_on_user_id"

end

Why insurances table has no foreign keys? Thank you

Answer 1

Run the following migrations:

rails g migration AddUserIDToInsurances user:references

rails g migration AddVehicleIDToInsurances vehicle:references

Then run rake db:migrate. This should add the two foreign keys you mentioned to your insurances table.