FEATURE: add parameter that allows you to filter directory items on user

adding ?username= will filter directory_items.json by the username

app/controllers/directory_items_controller.rb

@@ -35,6 +35,15 @@ class DirectoryItemsController < ApplicationController
       end
     end
 
+    if params[:username]
+      user_id = User.where(username_lower: params[:username].to_s.downcase).pluck(:id).first
+      if user_id
+        result = result.where(user_id: user_id)
+      else
+        result = result.where('false')
+      end
+    end
+
     result = result.order('users.username')
     result_count = result.dup.count
     result = result.limit(PAGE_SIZE).offset(PAGE_SIZE * page).to_a