WIP diary comment subscriptions

db/migrate/20161002153425_add_join_table_between_users_and_diary_entries.rb

@@ -0,0 +1,23 @@
+class AddJoinTableBetweenUsersAndDiaryEntries < ActiveRecord::Migration
+  def change
+    create_table :diary_entries_subscribers, :id => false do |t|
+      t.column :subscriber_id, :bigint, :null => false
+      t.column :diary_entry_id, :bigint, :null => false
+    end
+
+    add_foreign_key :diary_entries_subscribers, :users, :column => :subscriber_id, :name => "diary_entries_subscribers_subscriber_id_fkey"
+    add_foreign_key :diary_entries_subscribers, :diary_entries, :column => :diary_entry_id, :name => "diary_entries_subscribers_changeset_id_fkey"
+
+    add_index :diary_entries_subscribers, [:subscriber_id, :diary_entry_id], :unique => true, :name => "index_diary_subscribers_on_subscriber_id_and_diary_id"
+    add_index :diary_entries_subscribers, [:diary_entry_id]
+  end
+
+  def up
+    DiaryEntry.find_each do |diary_entry|
+      diary_entry.subscribers << diary_entry.user unless diary_entry.subscribers.exists?(diary_entry.user.id)
+    end
+  end
+
+  def down
+  end
+end