Simplify default beamer handling

app/controllers/beamers_controller.rb

@@ -20,7 +20,7 @@ class BeamersController < ApplicationController
   # GET /tournaments/:tournament_id/beamers/by_name?name=beamername
   def by_name
     beamer = @tournament.beamers.find_by(name: params[:name])
-    beamer ||= @tournament.beamers.default_beamer.first
+    beamer ||= @tournament.beamers.find_by(name: Beamer::DEFAULT_NAME)
     if beamer
       render json: beamer
     else
@@ -64,6 +64,6 @@ class BeamersController < ApplicationController
   end
 
   def beamer_params
-    params.permit(:name, :display_state, :is_default, :qr_code_url, :logo_url)
+    params.permit(:name, :display_state, :qr_code_url, :logo_url)
   end
 end

app/models/beamer.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 class Beamer < ApplicationRecord
+  DEFAULT_NAME = 'default'
   DISPLAY_STATES = %w[
     matches_all matches_in_progress matches_upcoming matches_not_started
     matches_finished groups between_games during_game
@@ -11,7 +12,5 @@ class Beamer < ApplicationRecord
   validates :name, presence: true, uniqueness: { scope: :tournament_id }
   validates :display_state, presence: true, inclusion: { in: DISPLAY_STATES }
 
-  scope :default_beamer, -> { where(is_default: true) }
-
   delegate :owner, to: :tournament
 end

app/models/tournament.rb

@@ -16,6 +16,7 @@ class Tournament < ApplicationRecord
   alias_attribute :owner, :user
 
   after_initialize :generate_code
+  after_create_commit :ensure_default_beamer!
 
   def matches
     [stages.map(&:matches), stages.map { |s| s.groups.map(&:matches) }].flatten
@@ -50,4 +51,10 @@ class Tournament < ApplicationRecord
     errors.add(:playoff_teams_amount,
                'playoff_teams_amount needs to be a positive power of two')
   end
+
+  def ensure_default_beamer!
+    beamers.find_or_create_by!(name: Beamer::DEFAULT_NAME) do |beamer|
+      beamer.display_state = 'matches_all'
+    end
+  end
 end

app/serializers/beamer_serializer.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 class BeamerSerializer < ApplicationSerializer
-  attributes :name, :display_state, :is_default, :qr_code_url, :logo_url
+  attributes :name, :display_state, :qr_code_url, :logo_url
 end

db/migrate/20260416102000_backfill_default_beamers_by_name.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+class BackfillDefaultBeamersByName < ActiveRecord::Migration[7.0]
+  DEFAULT_BEAMER_NAME = 'default'
+
+  class MigrationTournament < ApplicationRecord
+    self.table_name = 'tournaments'
+  end
+
+  class MigrationBeamer < ApplicationRecord
+    self.table_name = 'beamers'
+  end
+
+  def up
+    MigrationTournament.find_each do |tournament|
+      beamers = MigrationBeamer.where(tournament_id: tournament.id)
+      next if beamers.exists?(name: DEFAULT_BEAMER_NAME)
+
+      legacy_default = beamers.find_by(is_default: true)
+
+      if legacy_default
+        legacy_default.update_columns(name: DEFAULT_BEAMER_NAME)
+      else
+        MigrationBeamer.create!(
+          tournament_id: tournament.id,
+          name: DEFAULT_BEAMER_NAME,
+          display_state: 'matches_all'
+        )
+      end
+    end
+  end
+
+  def down
+    MigrationBeamer.where(name: DEFAULT_BEAMER_NAME).where.not(tournament_id: nil).find_each do |beamer|
+      next unless MigrationBeamer.where(tournament_id: beamer.tournament_id).count == 1
+
+      beamer.delete
+    end
+  end
+end

spec/controllers/beamers_controller_spec.rb

@@ -6,8 +6,8 @@ RSpec.describe BeamersController, type: :controller do
   before do
     @tournament = create(:tournament)
     @owner = @tournament.owner
+    @default_beamer = @tournament.beamers.find_by!(name: Beamer::DEFAULT_NAME)
     @beamer = create(:beamer, tournament: @tournament)
-    @default_beamer = create(:default_beamer, tournament: @tournament)
   end
 
   describe 'GET #index' do
@@ -47,18 +47,18 @@ RSpec.describe BeamersController, type: :controller do
       expect(response).to be_successful
       body = deserialize_response response
       expect(body[:name]).to eq(@default_beamer.name)
-      expect(body[:is_default]).to be true
     end
 
     it 'falls back to default beamer when name param is missing' do
       get :by_name, params: { tournament_id: @tournament.to_param }
       expect(response).to be_successful
       body = deserialize_response response
-      expect(body[:is_default]).to be true
+      expect(body[:name]).to eq(Beamer::DEFAULT_NAME)
     end
 
-    it 'returns 404 when no beamers exist at all' do
+    it 'returns 404 when all beamers were deleted' do
       empty_tournament = create(:tournament)
+      empty_tournament.beamers.destroy_all
       get :by_name, params: { tournament_id: empty_tournament.to_param, name: 'anything' }
       expect(response).to have_http_status(:not_found)
     end
@@ -66,7 +66,7 @@ RSpec.describe BeamersController, type: :controller do
 
   describe 'POST #create' do
     let(:valid_params) do
-      { name: 'new-beamer', display_state: 'groups', is_default: false }
+      { name: 'new-beamer', display_state: 'groups' }
     end
 
     context 'as owner' do

spec/controllers/tournaments_controller_spec.rb

@@ -259,6 +259,14 @@ RSpec.describe TournamentsController, type: :controller do
           expect(included_teams).to match_array(@teams)
         end
 
+        it 'creates a default beamer automatically' do
+          post :create, params: create_playoff_tournament_data
+          body = deserialize_response response
+          tournament = Tournament.find(body[:id])
+
+          expect(tournament.beamers.pluck(:name)).to include(Beamer::DEFAULT_NAME)
+        end
+
         context 'with parameter group_stage=true' do
           before do
             post :create, params: create_group_tournament_data

spec/factories/beamers.rb

@@ -4,12 +4,10 @@ FactoryBot.define do
   factory :beamer do
     sequence(:name) { |n| "beamer-#{n}" }
     display_state { 'matches_all' }
-    is_default { false }
     tournament
 
     factory :default_beamer do
       name { 'default' }
-      is_default { true }
     end
   end
 end

spec/models/beamer_spec.rb

@@ -36,19 +36,6 @@ RSpec.describe Beamer, type: :model do
     it { should belong_to :tournament }
   end
 
-  describe 'scopes' do
-    describe '.default_beamer' do
-      it 'returns only default beamers' do
-        tournament = create(:tournament)
-        default = create(:default_beamer, tournament: tournament)
-        create(:beamer, tournament: tournament)
-
-        result = tournament.beamers.default_beamer
-        expect(result).to contain_exactly(default)
-      end
-    end
-  end
-
   describe '#owner' do
     it 'delegates to tournament' do
       beamer = create(:beamer)

spec/models/tournament_spec.rb

@@ -32,6 +32,14 @@ RSpec.describe Tournament, type: :model do
     it { should have_many :beamers }
   end
 
+  describe 'default beamer' do
+    it 'creates a default beamer automatically' do
+      tournament = create(:tournament)
+
+      expect(tournament.beamers.pluck(:name)).to include(Beamer::DEFAULT_NAME)
+    end
+  end
+
   describe '#matches' do
     context 'group stage tournament' do
       before do