Add teams method to group,match,stage

It returns the unique teams that compete within the object

app/models/group.rb

@@ -4,4 +4,8 @@ class Group < ApplicationRecord
   belongs_to :stage
   has_many :matches, dependent: :destroy
   has_many :group_scores, dependent: :destroy
+
+  def teams
+    matches.map(&:teams).flatten.uniq
+  end
 end

app/models/match.rb

@@ -11,6 +11,10 @@ class Match < ApplicationRecord
 
   validate :stage_xor_group
 
+  def teams
+    match_scores.map(&:team).flatten.uniq
+  end
+
   private
 
   def stage_xor_group

app/models/stage.rb

@@ -4,4 +4,8 @@ class Stage < ApplicationRecord
   belongs_to :tournament
   has_many :matches, dependent: :destroy
   has_many :groups, dependent: :destroy
+
+  def teams
+    groups.map(&:teams).flatten.uniq
+  end
 end