add relevant stages relation

app/models/conference.rb

@@ -8,6 +8,9 @@ class Conference < ApplicationRecord
 
   validates :time_zone, presence: true, inclusion: { in: ActiveSupport::TimeZone.all.map(&:name) }
 
+  has_many :relevant_stage_links, class_name: 'RelevantStage'
+  has_many :relevant_stages, through: :relevant_stage_links, source: :stage
+
   def days
     (starts_at.to_date..ends_at.to_date)
   end

app/models/relevant_stage.rb

+class RelevantStage < ApplicationRecord
+  belongs_to :conference
+  belongs_to :stage
+
+  validates :conference_id, uniqueness: { scope: :stage_id }
+end

app/models/stage.rb

@@ -3,4 +3,7 @@ class Stage < ApplicationRecord
   has_many :sessions
 
   validates :ref_id, uniqueness: { scope: :conference_id }
+
+  has_many :relevant_stage_links, class_name: 'RelevantStage'
+  has_many :relevant_conferences, through: :relevant_stage_links, source: :conference
 end

db/migrate/20240527191332_create_relevant_stages.rb

+class CreateRelevantStages < ActiveRecord::Migration[7.1]
+  def change
+    create_table :relevant_stages do |t|
+      t.references :conference, null: false, foreign_key: true
+      t.references :stage, null: false, foreign_key: true
+
+      t.timestamps
+    end
+
+    add_index :relevant_stages, [:conference_id, :stage_id], unique: true
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.1].define(version: 2024_05_26_165259) do
+ActiveRecord::Schema[7.1].define(version: 2024_05_27_191332) do
   create_table "assignments", force: :cascade do |t|
     t.integer "user_id", null: false
     t.integer "session_id", null: false
@@ -72,6 +72,16 @@ ActiveRecord::Schema[7.1].define(version: 2024_05_26_165259) do
     t.datetime "updated_at", null: false
   end
 
+  create_table "relevant_stages", force: :cascade do |t|
+    t.integer "conference_id", null: false
+    t.integer "stage_id", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["conference_id", "stage_id"], name: "index_relevant_stages_on_conference_id_and_stage_id", unique: true
+    t.index ["conference_id"], name: "index_relevant_stages_on_conference_id"
+    t.index ["stage_id"], name: "index_relevant_stages_on_stage_id"
+  end
+
   create_table "revision_sets", force: :cascade do |t|
     t.integer "conference_id", null: false
     t.datetime "created_at", null: false
@@ -260,6 +270,8 @@ ActiveRecord::Schema[7.1].define(version: 2024_05_26_165259) do
 
   add_foreign_key "assignments", "sessions"
   add_foreign_key "assignments", "users"
+  add_foreign_key "relevant_stages", "conferences"
+  add_foreign_key "relevant_stages", "stages"
   add_foreign_key "revision_sets", "conferences"
   add_foreign_key "revisions", "conferences"
   add_foreign_key "session_speakers", "sessions"

test/fixtures/relevant_stages.yml

+# Read about fixtures at https://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
+
+one:
+  conference: one
+  stage: one
+
+two:
+  conference: two
+  stage: two

test/models/relevant_stage_test.rb

+require "test_helper"
+
+class RelevantStageTest < ActiveSupport::TestCase
+  # test "the truth" do
+  #   assert true
+  # end
+end