ADD db schema in models

app/models/open_user.rb

@@ -1,3 +1,21 @@
+# == Schema Information
+#
+# Table name: open_users
+#
+#  id         :integer          not null, primary key
+#  user_id    :integer
+#  type       :string(255)
+#  uid        :string(255)
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
+#  extra      :text(65535)
+#
+# Indexes
+#
+#  index_open_users_on_type_and_uid  (type,uid) UNIQUE
+#  index_open_users_on_user_id       (user_id)
+#
+
 class OpenUser < ApplicationRecord
   belongs_to :user
 
@@ -8,4 +26,4 @@ class OpenUser < ApplicationRecord
   def can_bind_cache_key
     "open_user:#{type}:#{uid}:can_bind"
   end
-end
+end