Fix #16 - Optimize n+1 queries when checking reblogged/favourited values for status lists in API

app/models/account.rb

@@ -48,6 +48,8 @@ class Account < ApplicationRecord
   scope :with_followers, -> { where('(select count(f.id) from follows as f where f.target_account_id = accounts.id) > 0') }
   scope :expiring, -> (time) { where(subscription_expires_at: nil).or(where('subscription_expires_at < ?', time)).remote.with_followers }
 
+  scope :with_counters, -> { select('accounts.*, (select count(f.id) from follows as f where f.target_account_id = accounts.id) as followers_count, (select count(f.id) from follows as f where f.account_id = accounts.id) as following_count, (select count(s.id) from statuses as s where s.account_id = accounts.id) as statuses_count') }
+
   def follow!(other_account)
     active_relationships.where(target_account: other_account).first_or_create!(target_account: other_account)
   end

app/models/follow_suggestion.rb

@@ -22,7 +22,7 @@ END
 
     account_ids  = results['data'].map(&:first)
     blocked_ids  = Block.where(account_id: for_account_id).pluck(:target_account_id)
-    accounts_map = Account.where(id: account_ids - blocked_ids).map { |a| [a.id, a] }.to_h
+    accounts_map = Account.where(id: account_ids - blocked_ids).with_counters.map { |a| [a.id, a] }.to_h
 
     account_ids.map { |id| accounts_map[id] }.compact
   rescue Neography::NeographyError, Excon::Error::Socket => e

app/models/status.rb

@@ -2,7 +2,7 @@ class Status < ApplicationRecord
   include Paginable
   include Streamable
 
-  belongs_to :account, inverse_of: :statuses
+  belongs_to :account, -> { with_counters }, inverse_of: :statuses
 
   belongs_to :thread, foreign_key: 'in_reply_to_id', class_name: 'Status', inverse_of: :replies
   belongs_to :reblog, foreign_key: 'reblog_of_id', class_name: 'Status', inverse_of: :reblogs
@@ -90,11 +90,11 @@ class Status < ApplicationRecord
   end
 
   def self.favourites_map(status_ids, account_id)
-    Favourite.where(status_id: status_ids).where(account_id: account_id).map { |f| [f.status_id, true] }.to_h
+    Favourite.select('status_id').where(status_id: status_ids).where(account_id: account_id).map { |f| [f.status_id, true] }.to_h
   end
 
   def self.reblogs_map(status_ids, account_id)
-    where(reblog_of_id: status_ids).where(account_id: account_id).map { |s| [s.reblog_of_id, true] }.to_h
+    select('reblog_of_id').where(reblog_of_id: status_ids).where(account_id: account_id).map { |s| [s.reblog_of_id, true] }.to_h
   end
 
   before_validation do