weibo: normalize weibo urls in artist entries.

Normalize all Weibo URLs in artist entries to one of these forms:

* https://www.weibo.com/u/5399876326
* https://www.weibo.com/p/1005055399876326
* https://www.weibo.com/chengziyou666

app/models/artist.rb

@@ -61,6 +61,17 @@ class Artist < ApplicationRecord
     def clear_url_string_changed
       self.url_string_changed = false
     end
+
+    class_methods do
+      # Find all artist URLs matching `regex`, and replace the `from` regex with the `to` string.
+      def rewrite_urls(regex, from, to)
+        Artist.transaction do
+          Artist.joins(:urls).where_regex("artist_urls.url", regex).find_each do |artist|
+            artist.update!(url_string: artist.url_string.gsub(from, to))
+          end
+        end
+      end
+    end
   end
 
   concerning :NameMethods do