Ytukyg

I have following models in my app

class Building < ApplicationRecord



  has_many :rooms, dependent: :destroy

  ...



class Room < ApplicationRecord



  belongs_to :building

  has_many :lessons, dependent: :destroy

  ...



class Lesson < ApplicationRecord



  belongs_to :room

  belongs_to :teacher

  belongs_to :course

  ...

Everything worked fine between Bulding and its rooms with this code:

if Building.find_by_code("PAR").nil?

   building = Building.create!({title: "Areál Parukářka", code: "PAR"})



   par_rooms.each do |room|

      building.rooms << Room.create({title: room[0], code: room[1]})

   end 

end 

Now I want to add lessons to each Room. With the following code, no error is raised, and when I add some "puts" it says that the lessons has been created, but they are not available inside the controller/view. Here's the seed I use:

if Building.find_by_code("PAR").nil?

  building = Building.create!({title: "Areál Parukářka", code: "PAR"})



  par_rooms.each do |room|

    new_room = Room.create({title: room[0], code: room[1]})

    building.rooms << new_room

    lesson = Lesson.create({start_at: DateTime.new(2018, 11, 20, 8), end_at: DateTime.new(2018, 11, 20, 9, 30), durration: 45, room_id: new_room.id, teacher_id: nil, course_id: nil})

    new_room.lessons << lesson

  end

rooms and lessons tables has the following schema:

create_table "rooms", force: :cascade do |t|

    t.string "title"

    t.string "code"

    t.datetime "created_at", null: false

    t.datetime "updated_at", null: false

    t.integer "building_id"

    t.index ["building_id"], name: "index_rooms_on_building_id"

  end





create_table "lessons", force: :cascade do |t|

    t.datetime "start_at"

    t.datetime "end_at"

    t.integer "durration"

    t.datetime "created_at", null: false

    t.datetime "updated_at", null: false

    t.integer "room_id"

    t.integer "teacher_id"

    t.integer "course_id"

    t.index ["course_id"], name: "index_lessons_on_course_id"

    t.index ["room_id"], name: "index_lessons_on_room_id"

    t.index ["teacher_id"], name: "index_lessons_on_teacher_id"

  end

lesson = Lesson.create({

  start_at: DateTime.new(2018, 11, 20, 8), 

  end_at: DateTime.new(2018, 11, 20, 9, 30), 

  durration: 45, room_id: new_room.id, 

  teacher_id: nil,     # is problematic with your model

  course_id: nil})     # is problematic with your model

your model suggests that all relations are needed.
you should, if there are empty relations given, mark

belongs_to :teacher, optional: true

as optional.

not that this solves your problem, but it should be the right direction.
for more ideas you should provide the schemas for teacher, course, room and building.

Try new_room = building.rooms.create({title: room[0], code: room[1]}) , and remove the line building.rooms << new_room