Change TopicViewItem to allow null IP address

app/models/topic_view_item.rb

@@ -58,13 +58,12 @@ end
 #  topic_id   :integer          not null
 #  viewed_at  :date             not null
 #  user_id    :integer
-#  ip_address :inet             not null
+#  ip_address :inet
 #
 # Indexes
 #
 #  index_topic_views_on_topic_id_and_viewed_at  (topic_id,viewed_at)
 #  index_topic_views_on_user_id_and_viewed_at   (user_id,viewed_at)
 #  index_topic_views_on_viewed_at_and_topic_id  (viewed_at,topic_id)
-#  ip_address_topic_id_topic_views              (ip_address,topic_id) UNIQUE
-#  user_id_topic_id_topic_views                 (user_id,topic_id) UNIQUE
+#  uniq_ip_or_user_id_topic_views               (user_id,ip_address,topic_id) UNIQUE
 #

db/migrate/20180521175611_change_indexes_topic_view_item.rb

@@ -0,0 +1,25 @@
+class ChangeIndexesTopicViewItem < ActiveRecord::Migration[5.1]
+  def up
+    begin
+      Migration::SafeMigrate.disable!
+      change_column :topic_views, :ip_address, :inet, null: true
+    ensure
+      Migration::SafeMigrate.enable!
+    end
+
+    remove_index :topic_views,
+      column: [:ip_address, :topic_id],
+      name: :ip_address_topic_id_topic_views,
+      unique: true
+    remove_index :topic_views,
+      column: [:user_id, :topic_id],
+      name: :user_id_topic_id_topic_views,
+      unique: true
+    add_index :topic_views, [:user_id, :ip_address, :topic_id],
+      name: :uniq_ip_or_user_id_topic_views,
+      unique: true
+  end
+
+  def down
+  end
+end