Add completions

app/models/completion.rb

@@ -0,0 +1,7 @@
+class Completion < ApplicationRecord
+  belongs_to :contest
+  belongs_to :contestant
+  belongs_to :puzzle
+
+  validates :time_seconds, presence: true
+end

app/models/contest.rb

@@ -1,5 +1,7 @@
 class Contest < ApplicationRecord
   belongs_to :user
+
+  has_many :completions, dependent: :destroy
   has_many :contestants, dependent: :destroy
   has_many :puzzles, dependent: :destroy
 end

app/models/contestant.rb

@@ -1,4 +1,7 @@
 class Contestant < ApplicationRecord
   belongs_to :contest
+
+  has_many :completions
+
   validates :name, presence: true
 end

app/models/puzzle.rb

@@ -1,6 +1,9 @@
 class Puzzle < ApplicationRecord
   belongs_to :contest
+
+  has_many :completions
   has_one_attached :image
+
   validates :name, presence: true
   validates :brand, presence: true
 end