#41

backend/app/models/gekanator_game.rb

@@ -0,0 +1,18 @@
+class GekanatorGame < ApplicationRecord
+  belongs_to :user, optional: true
+  belongs_to :guessed_post, class_name: 'Post'
+  belongs_to :correct_post, class_name: 'Post', optional: true
+
+  validates :answers, presence: true
+  validates :question_count, numericality: { greater_than_or_equal_to: 0 }
+  validates :won, inclusion: { in: [true, false] }
+  validate :correct_post_required_when_lost
+
+  private
+
+  def correct_post_required_when_lost
+    return if won || correct_post_id.present?
+
+    errors.add(:correct_post_id, '外れた時は正解の投稿を指定してくださぃ．')
+  end
+end