Add relation between Tournament and User

app/models/tournament.rb

@@ -1,4 +1,8 @@
 # frozen_string_literal: true
 
 class Tournament < ApplicationRecord
+  validates :name, presence: true
+  validates :code, presence: true, uniqueness: true
+
+  belongs_to :user
 end

app/models/user.rb

@@ -7,4 +7,6 @@ class User < ApplicationRecord
   include DeviseTokenAuth::Concerns::User
 
   validates :username, presence: true, uniqueness: true
+
+  has_many :tournaments, dependent: :destroy
 end

db/migrate/0000_create_schema.rb

@@ -40,11 +40,14 @@ class CreateSchema < ActiveRecord::Migration[5.2]
     end
 
     create_table :tournaments do |t|
-      t.string :name
-      t.string :code
+      t.string :name, null: false
+      t.string :code, null: false
       t.string :description
       t.boolean :public, default: true
 
+      # relation to owner
+      t.belongs_to :user, index: true, foreign_key: true, null: false
+
       t.timestamps
     end