Association between 2 tables doesn't work - ruby-on-rails

Question

I'm new to RoR and I want to create simple page like a task manager (to add and remove tasks) so I created 2 tables with association between them (Track and Item).
Here is 2 models:
class Item < ApplicationRecord
belongs_to :track, optional: :true
end
class Track < ApplicationRecord
has_many :items, dependent: :destroy
end
And I need to set association when I create or delete any track item. But when I create it I just see my track item (with an empty field in associated table)
For example:
rails c
Track.create(item: 'Asafa Pauel', description: 'This is a description') - works fine (added all field to db)
Item.all - track_id field is empty - but it should show id of track item. Why is this?
And my Tracks controller:
class TracksController < ApplicationController
def index
#track = Track.all
end
def show
#track = Track.all
end
def new
#track = Track.new
end
def create
#track = Track.new(track_params)
#item = Item.new(track_id: #track.id)
if #track.save! && #item.save!
flash[:success] = "It works!"
redirect_to tracks_path
else
flash[:success] = "Its wrong!"
end
end
private
def track_params
params.require(:track).permit(:item, :description)
end
end
And Items controller:
class ItemsController < ApplicationController
def create
#item = Item.new(item_params)
end
private
def item_params
params.require(:item).permit(:track_id)
end
end
And db schema:
ActiveRecord::Schema.define(version: 2019_05_23_112947) do
enable_extension "plpgsql"
create_table "items", force: :cascade do |t|
t.bigint "track_id"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.index ["track_id"], name: "index_items_on_track_id"
end
create_table "tracks", force: :cascade do |t|
t.string "item"
t.string "description"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
end
Thanks in advance

Answer 1

Your new 'Track' object doesn't have an ID yet, so you can't assign its value to Item.track_id.
First you'll have to save the Track, then create a new Item.
Also, if you create a new Track from console, you won't trigger your "create" method in the controller: it will be called only if you create a new Track from browser.
If you want to create a new Item every time you create a Track, you'll have to do something like this in your model file "track.rb":
after_save :create_new_item
def create_new_item
self.items.create
end
P.S.: the "track.rb" file is in "app/models" in your Rails application.