Prevent 𝑛+1 on follower/following lists

app/controllers/user_controller.rb

@@ -21,6 +21,7 @@ class UserController < ApplicationController
     @relationships_last_id = @relationships.map(&:id).min
     @more_data_available = !@user.cursored_follower_relationships(last_id: @relationships_last_id, size: 1).count.zero?
     @users = @relationships.map(&:source)
+    find_own_relationships
 
     respond_to do |format|
       format.html { render "show_follow", locals: { type: :follower } }
@@ -33,6 +34,7 @@ class UserController < ApplicationController
     @relationships_last_id = @relationships.map(&:id).min
     @more_data_available = !@user.cursored_following_relationships(last_id: @relationships_last_id, size: 1).count.zero?
     @users = @relationships.map(&:target)
+    find_own_relationships
 
     respond_to do |format|
       format.html { render "show_follow", locals: { type: :friend } }
@@ -69,6 +71,16 @@ class UserController < ApplicationController
     @user = User.where("LOWER(screen_name) = ?", params[:username].downcase).includes(:profile).first!
   end
 
+  # Checks which of the displayed users are followed or blocked by the current user
+  #
+  # This prevents 𝑛+1 queries.
+  def find_own_relationships
+    return unless user_signed_in?
+
+    @own_followings = current_user.active_follow_relationships.where(target_id: @users.map(&:id)).select(:target_id).map(&:target_id)
+    @own_blocks = current_user.active_block_relationships.where(target_id: @users.map(&:id)).select(:target_id).map(&:target_id)
+  end
+
   def hidden_social_graph_redirect
     return if belongs_to_current_user? || !@user.privacy_hide_social_graph
 

app/views/user/_actions.html.haml

@@ -5,7 +5,7 @@
       %a.btn.btn-dark{ href: settings_profile_path } Edit profile
   - elsif user_signed_in?
     .d-grid.gap-2
-      - if current_user.following? user
+      - if @own_followings.include?(user.id)
         %button.btn.btn-primary{ type: :button, name: 'user-action', data: { action: :unfollow, type: type, target: user.screen_name } }
           = t("voc.unfollow")
       - else
@@ -19,7 +19,7 @@
           %a.dropdown-item.d-block.d-sm-none{ href: '#', data: { bs_target: '#modal-list-memberships', bs_toggle: :modal } }
             %i.fa.fa-list.fa-fw
             = t(".list")
-          - if current_user.blocking?(user)
+          - if @own_blocks.include?(user.id)
             %a.dropdown-item{ href: '#', data: { action: :unblock, target: user.screen_name } }
               %i.fa.fa-minus-circle.fa-fw
               %span.pe-none= t("voc.unblock")