Add message model

app/models/message.rb

@@ -0,0 +1,24 @@
+# == Schema Information
+#
+# Table name: messages
+#
+#  id           :integer          not null, primary key
+#  text         :string           not null
+#  time_seconds :integer          not null
+#  created_at   :datetime         not null
+#  updated_at   :datetime         not null
+#  contest_id   :integer          not null
+#
+# Indexes
+#
+#  index_messages_on_contest_id  (contest_id)
+#
+# Foreign Keys
+#
+#  contest_id  (contest_id => contests.id)
+#
+class Message < ApplicationRecord
+  belongs_to :contest
+
+  validates :text, presence: true
+end