Change TopicViewItem to allow null IP address

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