#409

backend/app/models/post.rb

@@ -57,7 +57,7 @@ class Post < ApplicationRecord
 
   attribute :version_no, :integer, default: 1
 
-  before_validation :normalise_url
+  before_validation :normalise_url, if: :will_save_change_to_url?
 
   validates :url, presence: true, uniqueness: true
   validates :video_ms, numericality: { only_integer: true, greater_than: 0 }, allow_nil: true
@@ -180,7 +180,7 @@ class Post < ApplicationRecord
 
     u.host = u.host.downcase if u.host
     u.path = u.path.sub(/\/\Z/, '') if u.path.present?
-    self.url = u.to_s
+    self.url = PostUrlSanitisationRule.sanitise(u.to_s)
   rescue URI::InvalidURIError
     ;
   end